Trabalhando com os tipos de dados Amazon Ion na Amazon QLDB - Banco de dados Amazon Quantum Ledger (AmazonQLDB)

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Trabalhando com os tipos de dados Amazon Ion na Amazon QLDB

Importante

Aviso de fim do suporte: os clientes existentes poderão usar a Amazon QLDB até o final do suporte em 31/07/2025. Para obter mais detalhes, consulte Migrar um Amazon QLDB Ledger para o Amazon Aurora Postgre. SQL

A Amazon QLDB armazena seus dados no formato Amazon Ion. Para trabalhar com dados emQLDB, você deve usar uma biblioteca Ion como dependência de uma linguagem de programação compatível.

Nesta seção, aprenda como converter dados de tipos nativos em seus equivalentes Ion e vice-versa. Este guia de referência mostra exemplos de código que usam o QLDB driver para processar dados de íons em um QLDB livro contábil. Inclui exemplos de código para Java,. NET(C#), Go, Node.js (TypeScript) e Python.

Pré-requisitos

Os exemplos de código a seguir pressupõem que você tenha uma instância de QLDB driver conectada a um livro contábil ativo com uma tabela chamadaExampleTable. A tabela contém um único documento existente que tem os oito campos a seguir:

  • ExampleBool

  • ExampleInt

  • ExampleFloat

  • ExampleDecimal

  • ExampleTimestamp

  • ExampleString

  • ExampleBlob

  • ExampleList

nota

Para fins dessa referência, suponha que o tipo armazenado em cada campo corresponda ao nome. Na prática, QLDB não impõe definições de esquema ou tipo de dados para campos de documentos.

Bool

Os exemplos de código a seguir mostram como processar o tipo booleano de Ion.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); boolean exampleBoolean = driver.execute((txn) -> { // Transforming a Java boolean to Ion boolean aBoolean = true; IonValue ionBool = ionSystem.newBool(aBoolean); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleBool = ?", ionBool); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleBool from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java boolean // Cast IonValue to IonBool first aBoolean = ((IonBool)ionValue).booleanValue(); } // exampleBoolean is now the value fetched from QLDB return aBoolean; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Transforming a C# bool to Ion. bool nativeBool = true; IIonValue ionBool = valueFactory.NewBool(nativeBool); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleBool = ?", ionBool); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleBool from ExampleTable"); }); bool? retrievedBool = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# bool. retrievedBool = ionValue.BoolValue; }
nota

Para converter em código síncrono, remova as palavras-chave await e async e altere o tipo IAsyncResult para IResult.

Go
exampleBool, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aBool := true // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleBool = ?", aBool) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleBool FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult bool err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleBool is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonBoolean(driver: QldbDriver): Promise<boolean> { return (driver.executeLambda(async (txn: TransactionExecutor) => { // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleBool = ?", true); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleBool FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Transforming Ion to a TypeScript Boolean const boolValue: boolean = ionValue.booleanValue(); return boolValue; }) ); }
Python
def update_and_query_ion_bool(txn): # QLDB can take in a Python bool a_bool = True # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleBool = ?", a_bool) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleBool FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python bool is a child class of Python bool a_bool = ion_value # example_bool is now the value fetched from QLDB return a_bool example_bool = driver.execute_lambda(lambda txn: update_and_query_ion_bool(txn))

Int

Os exemplos de código a seguir mostram como processar o tipo inteiro de Ion.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); int exampleInt = driver.execute((txn) -> { // Transforming a Java int to Ion int aInt = 256; IonValue ionInt = ionSystem.newInt(aInt); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleInt = ?", ionInt); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleInt from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java int // Cast IonValue to IonInt first aInt = ((IonInt)ionValue).intValue(); } // exampleInt is now the value fetched from QLDB return aInt; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Transforming a C# int to Ion. int nativeInt = 256; IIonValue ionInt = valueFactory.NewInt(nativeInt); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleInt = ?", ionInt); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleInt from ExampleTable"); }); int? retrievedInt = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# int. retrievedInt = ionValue.IntValue; }
nota

Para converter em código síncrono, remova as palavras-chave await e async e altere o tipo IAsyncResult para IResult.

Go
exampleInt, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aInt := 256 // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleInt = ?", aInt) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleInt FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult int err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleInt is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonInt(driver: QldbDriver): Promise<number> { return (driver.executeLambda(async (txn: TransactionExecutor) => { // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleInt = ?", 256); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleInt FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Transforming Ion to a TypeScript Number const intValue: number = ionValue.numberValue(); return intValue; }) ); }
Python
def update_and_query_ion_int(txn): # QLDB can take in a Python int a_int = 256 # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleInt = ?", a_int) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleInt FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python int is a child class of Python int a_int = ion_value # example_int is now the value fetched from QLDB return a_int example_int = driver.execute_lambda(lambda txn: update_and_query_ion_int(txn))

Float

Os exemplos de código a seguir mostram como processar o tipo float de Ion.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); float exampleFloat = driver.execute((txn) -> { // Transforming a Java float to Ion float aFloat = 256; IonValue ionFloat = ionSystem.newFloat(aFloat); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleFloat = ?", ionFloat); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleFloat from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java float // Cast IonValue to IonFloat first aFloat = ((IonFloat)ionValue).floatValue(); } // exampleFloat is now the value fetched from QLDB return aFloat; });
.NET

Usar C# float

using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Transforming a C# float to Ion. float nativeFloat = 256; IIonValue ionFloat = valueFactory.NewFloat(nativeFloat); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleFloat = ?", ionFloat); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleFloat from ExampleTable"); }); float? retrievedFloat = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# float. We cast ionValue.DoubleValue to a float // but be cautious, this is a down-cast and can lose precision. retrievedFloat = (float)ionValue.DoubleValue; }
nota

Para converter em código síncrono, remova as palavras-chave await e async e altere o tipo IAsyncResult para IResult.

Usar C# double

using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Transforming a C# double to Ion. double nativeDouble = 256; IIonValue ionFloat = valueFactory.NewFloat(nativeDouble); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleFloat = ?", ionFloat); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleFloat from ExampleTable"); }); double? retrievedDouble = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# double. retrievedDouble = ionValue.DoubleValue; }
nota

Para converter em código síncrono, remova as palavras-chave await e async e altere o tipo IAsyncResult para IResult.

Go
exampleFloat, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aFloat := float32(256) // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleFloat = ?", aFloat) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleFloat FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { // float64 would work as well var decodedResult float32 err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleFloat is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonFloat(driver: QldbDriver): Promise<number> { return (driver.executeLambda(async (txn: TransactionExecutor) => { // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleFloat = ?", 25.6); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleFloat FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Transforming Ion to a TypeScript Number const floatValue: number = ionValue.numberValue(); return floatValue; }) ); }
Python
def update_and_query_ion_float(txn): # QLDB can take in a Python float a_float = float(256) # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleFloat = ?", a_float) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleFloat FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python float is a child class of Python float a_float = ion_value # example_float is now the value fetched from QLDB return a_float example_float = driver.execute_lambda(lambda txn: update_and_query_ion_float(txn))

Decimal

Os exemplos de código a seguir mostram como processar o tipo decimal de Ion.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); double exampleDouble = driver.execute((txn) -> { // Transforming a Java double to Ion double aDouble = 256; IonValue ionDecimal = ionSystem.newDecimal(aDouble); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleDecimal = ?", ionDecimal); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleDecimal from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java double // Cast IonValue to IonDecimal first aDouble = ((IonDecimal)ionValue).doubleValue(); } // exampleDouble is now the value fetched from QLDB return aDouble; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Transforming a C# decimal to Ion. decimal nativeDecimal = 256.8723m; IIonValue ionDecimal = valueFactory.NewDecimal(nativeDecimal); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleDecimal = ?", ionDecimal); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleDecimal from ExampleTable"); }); decimal? retrievedDecimal = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# decimal. retrievedDecimal = ionValue.DecimalValue; }
nota

Para converter em código síncrono, remova as palavras-chave await e async e altere o tipo IAsyncResult para IResult.

Go
exampleDecimal, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aDecimal, err := ion.ParseDecimal("256") if err != nil { return nil, err } // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleDecimal = ?", aDecimal) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleDecimal FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult ion.Decimal err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleDecimal is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonDecimal(driver: QldbDriver): Promise<Decimal> { return (driver.executeLambda(async (txn: TransactionExecutor) => { // Creating a Decimal value. Decimal is an Ion Type with high precision let ionDecimal: Decimal = dom.load("2.5d-6").decimalValue(); // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleDecimal = ?", ionDecimal); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleDecimal FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Get the Ion Decimal ionDecimal = ionValue.decimalValue(); return ionDecimal; }) ); }
nota

Você também pode usar ionValue.numberValue() para transformar um íon decimal em um JavaScript número. O uso de ionValue.numberValue() tem melhor desempenho, mas é menos preciso.

Python
def update_and_query_ion_decimal(txn): # QLDB can take in a Python decimal a_decimal = Decimal(256) # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleDecimal = ?", a_decimal) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleDecimal FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python decimal is a child class of Python decimal a_decimal = ion_value # example_decimal is now the value fetched from QLDB return a_decimal example_decimal = driver.execute_lambda(lambda txn: update_and_query_ion_decimal(txn))

Timestamp

Os exemplos de código a seguir mostram como processar o tipo timestamp de Ion.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); Date exampleDate = driver.execute((txn) -> { // Transforming a Java Date to Ion Date aDate = new Date(); IonValue ionTimestamp = ionSystem.newUtcTimestamp(aDate); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleTimestamp = ?", ionTimestamp); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleTimestamp from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java Date // Cast IonValue to IonTimestamp first aDate = ((IonTimestamp)ionValue).dateValue(); } // exampleDate is now the value fetched from QLDB return aDate; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; using Amazon.IonDotnet; ... IValueFactory valueFactory = new ValueFactory(); // Convert C# native DateTime to Ion. DateTime nativeDateTime = DateTime.Now; // First convert it to a timestamp object from Ion. Timestamp timestamp = new Timestamp(nativeDateTime); // Then convert to Ion timestamp. IIonValue ionTimestamp = valueFactory.NewTimestamp(timestamp); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleTimestamp = ?", ionTimestamp); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleTimestamp from ExampleTable"); }); DateTime? retrievedDateTime = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# DateTime. retrievedDateTime = ionValue.TimestampValue.DateTimeValue; }
nota

Para converter em código síncrono, remova as palavras-chave await e async e altere o tipo IAsyncResult para IResult.

Go
exampleTimestamp, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aTimestamp := time.Date(2006, time.May, 20, 12, 30, 0, 0, time.UTC) if err != nil { return nil, err } // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleTimestamp = ?", aTimestamp) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleTimestamp FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult ion.Timestamp err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleTimestamp is now the value fetched from QLDB return decodedResult.GetDateTime(), nil } return nil, result.Err() })
Node.js
async function queryIonTimestamp(driver: QldbDriver): Promise<Date> { return (driver.executeLambda(async (txn: TransactionExecutor) => { let exampleDateTime: Date = new Date(Date.now()); // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleTimestamp = ?", exampleDateTime); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleTimestamp FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Transforming Ion to a TypeScript Date exampleDateTime = ionValue.timestampValue().getDate(); return exampleDateTime; }) ); }
Python
def update_and_query_ion_timestamp(txn): # QLDB can take in a Python timestamp a_datetime = datetime.now() # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleTimestamp = ?", a_datetime) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleTimestamp FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python timestamp is a child class of Python datetime a_timestamp = ion_value # example_timestamp is now the value fetched from QLDB return a_timestamp example_timestamp = driver.execute_lambda(lambda txn: update_and_query_ion_timestamp(txn))

String

Os exemplos de código a seguir mostram como processar o tipo segmento de Ion.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); String exampleString = driver.execute((txn) -> { // Transforming a Java String to Ion String aString = "Hello world!"; IonValue ionString = ionSystem.newString(aString); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleString = ?", ionString); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleString from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java String // Cast IonValue to IonString first aString = ((IonString)ionValue).stringValue(); } // exampleString is now the value fetched from QLDB return aString; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Convert C# string to Ion. String nativeString = "Hello world!"; IIonValue ionString = valueFactory.NewString(nativeString); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleString = ?", ionString); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleString from ExampleTable"); }); String retrievedString = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# string. retrievedString = ionValue.StringValue; }
nota

Para converter em código síncrono, remova as palavras-chave await e async e altere o tipo IAsyncResult para IResult.

Go
exampleString, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aString := "Hello World!" // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleString = ?", aString) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleString FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult string err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleString is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonString(driver: QldbDriver): Promise<string> { return (driver.executeLambda(async (txn: TransactionExecutor) => { // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleString = ?", "Hello World!"); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleString FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Transforming Ion to a TypeScript String const stringValue: string = ionValue.stringValue(); return stringValue; }) ); }
Python
def update_and_query_ion_string(txn): # QLDB can take in a Python string a_string = "Hello world!" # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleString = ?", a_string) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleString FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python string is a child class of Python string a_string = ion_value # example_string is now the value fetched from QLDB return a_string example_string = driver.execute_lambda(lambda txn: update_and_query_ion_string(txn))

Blob

Os exemplos de código a seguir mostram como processar o tipo blob de Ion.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); byte[] exampleBytes = driver.execute((txn) -> { // Transforming a Java byte array to Ion // Transform any arbitrary data to a byte array to store in QLDB String aString = "Hello world!"; byte[] aByteArray = aString.getBytes(); IonValue ionBlob = ionSystem.newBlob(aByteArray); // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleBlob = ?", ionBlob); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleBlob from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Transforming Ion to a Java byte array // Cast IonValue to IonBlob first aByteArray = ((IonBlob)ionValue).getBytes(); } // exampleBytes is now the value fetched from QLDB return aByteArray; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; using System.Text; ... IValueFactory valueFactory = new ValueFactory(); // Transform any arbitrary data to a byte array to store in QLDB. string nativeString = "Hello world!"; byte[] nativeByteArray = Encoding.UTF8.GetBytes(nativeString); // Transforming a C# byte array to Ion. IIonValue ionBlob = valueFactory.NewBlob(nativeByteArray); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleBlob = ?", ionBlob); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleBlob from ExampleTable"); }); byte[] retrievedByteArray = null; // Assume there is only one document in ExampleTable. await foreach (IIonValue ionValue in selectResult) { // Transforming Ion to a C# byte array. retrievedByteArray = ionValue.Bytes().ToArray(); }
nota

Para converter em código síncrono, remova as palavras-chave await e async e altere o tipo IAsyncResult para IResult.

Go
exampleBlob, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aBlob := []byte("Hello World!") // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleBlob = ?", aBlob) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleBlob FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult []byte err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleBlob is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonBlob(driver: QldbDriver): Promise<Uint8Array> { return (driver.executeLambda(async (txn: TransactionExecutor) => { const enc = new TextEncoder(); let blobValue: Uint8Array = enc.encode("Hello World!"); // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleBlob = ?", blobValue); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleBlob FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Transforming Ion to TypeScript Uint8Array blobValue = ionValue.uInt8ArrayValue(); return blobValue; }) ); }
Python
def update_and_query_ion_blob(txn): # QLDB can take in a Python byte array a_string = "Hello world!" a_byte_array = str.encode(a_string) # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleBlob = ?", a_byte_array) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleBlob FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python blob is a child class of Python byte array a_blob = ion_value # example_blob is now the value fetched from QLDB return a_blob example_blob = driver.execute_lambda(lambda txn: update_and_query_ion_blob(txn))

Listar

Os exemplos de código a seguir mostram como processar o tipo lista de Ion.

Java
// Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); List<Integer> exampleList = driver.execute((txn) -> { // Transforming a Java List to Ion List<Integer> aList = new ArrayList<>(); // Add 5 Integers to the List for the sake of example for (int i = 0; i < 5; i++) { aList.add(i); } // Create an empty Ion List IonList ionList = ionSystem.newEmptyList(); // Add the 5 Integers to the Ion List for (Integer i : aList) { // Convert each Integer to Ion ints first to add it to the Ion List ionList.add(ionSystem.newInt(i)); } // Insertion into QLDB txn.execute("UPDATE ExampleTable SET ExampleList = ?", (IonValue) ionList); // Fetching from QLDB Result result = txn.execute("SELECT VALUE ExampleList from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Iterate through the Ion List to map it to a Java List List<Integer> intList = new ArrayList<>(); for (IonValue ionInt : (IonList)ionValue) { // Convert the 5 Ion ints to Java Integers intList.add(((IonInt)ionInt).intValue()); } aList = intList; } // exampleList is now the value fetched from QLDB return aList; });
.NET
using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; using System.Collections.Generic; ... IValueFactory valueFactory = new ValueFactory(); // Transforming a C# list to Ion. IIonValue ionList = valueFactory.NewEmptyList(); foreach (int i in new List<int> {0, 1, 2, 3, 4}) { // Convert to Ion int and add to Ion list. ionList.Add(valueFactory.NewInt(i)); } IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleList = ?", ionList); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleList from ExampleTable"); }); List<int> retrievedList = new List<int>(); await foreach (IIonValue ionValue in selectResult) { // Iterate through the Ion List to map it to a C# list. foreach (IIonValue ionInt in ionValue) { retrievedList.Add(ionInt.IntValue); } }
nota

Para converter em código síncrono, remova as palavras-chave await e async e altere o tipo IAsyncResult para IResult.

Go
exampleList, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aList := []int{1, 2, 3, 4, 5} // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleList = ?", aList) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleList FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult []int err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleList is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonList(driver: QldbDriver): Promise<number[]> { return (driver.executeLambda(async (txn: TransactionExecutor) => { let listOfNumbers: number[] = [1, 2, 3, 4, 5]; // Updating QLDB await txn.execute("UPDATE ExampleTable SET ExampleList = ?", listOfNumbers); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT VALUE ExampleList FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // Get Ion List const ionList: dom.Value[] = ionValue.elements(); // Iterate through the Ion List to map it to a JavaScript Array let intList: number[] = []; ionList.forEach(item => { // Transforming Ion to a TypeScript Number const intValue: number = item.numberValue(); intList.push(intValue); }); listOfNumbers = intList; return listOfNumbers; }) ); }
Python
def update_and_query_ion_list(txn): # QLDB can take in a Python list a_list = list() for i in range(0, 5): a_list.append(i) # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleList = ?", a_list) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleList FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python blob is a child class of Python list a_list = ion_value # example_list is now the value fetched from QLDB return a_list example_list = driver.execute_lambda(lambda txn: update_and_query_ion_list(txn))

struct

EmQLDB, struct os tipos de dados são particularmente exclusivos de outros tipos de íons. Os documentos de nível superior que você insere em uma tabela devem ser do tipo struct. Um campo de documento também pode armazenar um struct aninhado.

Para simplificar, os exemplos a seguir definem um documento que tem somente os campos ExampleString e ExampleInt.

Java
class ExampleStruct { public String exampleString; public int exampleInt; public ExampleStruct(String exampleString, int exampleInt) { this.exampleString = exampleString; this.exampleInt = exampleInt; } } // Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); ExampleStruct examplePojo = driver.execute((txn) -> { // Transforming a POJO to Ion ExampleStruct aPojo = new ExampleStruct("Hello world!", 256); // Create an empty Ion struct IonStruct ionStruct = ionSystem.newEmptyStruct(); // Map the fields of the POJO to Ion values and put them in the Ion struct ionStruct.add("ExampleString", ionSystem.newString(aPojo.exampleString)); ionStruct.add("ExampleInt", ionSystem.newInt(aPojo.exampleInt)); // Insertion into QLDB txn.execute("INSERT INTO ExampleTable ?", ionStruct); // Fetching from QLDB Result result = txn.execute("SELECT * from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Map the fields of the Ion struct to Java values and construct a new POJO ionStruct = (IonStruct)ionValue; IonString exampleString = (IonString)ionStruct.get("ExampleString"); IonInt exampleInt = (IonInt)ionStruct.get("ExampleInt"); aPojo = new ExampleStruct(exampleString.stringValue(), exampleInt.intValue()); } // examplePojo is now the document fetched from QLDB return aPojo; });

Como alternativa, você pode usar a biblioteca Jackson para mapear tipos de dados de e para o Ion. A biblioteca oferece suporte aos outros tipos de dados de Ion, mas este exemplo se concentra no tipo struct.

class ExampleStruct { public String exampleString; public int exampleInt; @JsonCreator public ExampleStruct(@JsonProperty("ExampleString") String exampleString, @JsonProperty("ExampleInt") int exampleInt) { this.exampleString = exampleString; this.exampleInt = exampleInt; } @JsonProperty("ExampleString") public String getExampleString() { return this.exampleString; } @JsonProperty("ExampleInt") public int getExampleInt() { return this.exampleInt; } } // Instantiate an IonSystem from the Ion library IonSystem ionSystem = IonSystemBuilder.standard().build(); // Instantiate an IonObjectMapper from the Jackson library IonObjectMapper ionMapper = new IonValueMapper(ionSystem); ExampleStruct examplePojo = driver.execute((txn) -> { // Transforming a POJO to Ion ExampleStruct aPojo = new ExampleStruct("Hello world!", 256); IonValue ionStruct; try { // Use the mapper to convert Java objects into Ion ionStruct = ionMapper.writeValueAsIonValue(aPojo); } catch (IOException e) { // Wrap the exception and throw it for the sake of simplicity in this example throw new RuntimeException(e); } // Insertion into QLDB txn.execute("INSERT INTO ExampleTable ?", ionStruct); // Fetching from QLDB Result result = txn.execute("SELECT * from ExampleTable"); // Assume there is only one document in ExampleTable for (IonValue ionValue : result) { // Use the mapper to convert Ion to Java objects try { aPojo = ionMapper.readValue(ionValue, ExampleStruct.class); } catch (IOException e) { // Wrap the exception and throw it for the sake of simplicity in this example throw new RuntimeException(e); } } // examplePojo is now the document fetched from QLDB return aPojo; });
.NET

Use a Amazon. QLDB.Driver.Biblioteca de serialização para mapear tipos de dados C# nativos de e para o Ion. A biblioteca oferece suporte aos outros tipos de dados de Ion, mas este exemplo se concentra no tipo struct.

using Amazon.QLDB.Driver.Generic; using Amazon.QLDB.Driver.Serialization; ... IAsyncQldbDriver driver = AsyncQldbDriver.Builder() .WithLedger("vehicle-registration") // Add Serialization library .WithSerializer(new ObjectSerializer()) .Build(); // Creating a C# POCO. ExampleStruct exampleStruct = new ExampleStruct { ExampleString = "Hello world!", ExampleInt = 256 }; IAsyncResult<ExampleStruct> selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute(txn.Query<Document>("UPDATE ExampleTable SET ExampleStruct = ?", exampleStruct)); // Fetching from QLDB. return await txn.Execute(txn.Query<ExampleStruct>("SELECT VALUE ExampleStruct from ExampleTable")); }); await foreach (ExampleStruct row in selectResult) { Console.WriteLine(row.ExampleString); Console.WriteLine(row.ExampleInt); }
nota

Para converter em código síncrono, remova as palavras-chave await e async e altere o tipo IAsyncResult para IResult.

Como alternativa, você pode usar a Amazon. IonDotnetBiblioteca .Builders para processar tipos de dados Ion.

using IAsyncResult = Amazon.QLDB.Driver.IAsyncResult; ... IValueFactory valueFactory = new ValueFactory(); // Creating Ion struct. IIonValue ionStruct = valueFactory.NewEmptyStruct(); ionStruct.SetField("ExampleString", valueFactory.NewString("Hello world!")); ionStruct.SetField("ExampleInt", valueFactory.NewInt(256)); IAsyncResult selectResult = await driver.Execute(async txn => { // Insertion into QLDB. await txn.Execute("UPDATE ExampleTable SET ExampleStruct = ?", ionStruct); // Fetching from QLDB. return await txn.Execute("SELECT VALUE ExampleStruct from ExampleTable"); }); string retrievedString = null; int? retrievedInt = null; await foreach (IIonValue ionValue in selectResult) { retrievedString = ionValue.GetField("ExampleString").StringValue; retrievedInt = ionValue.GetField("ExampleInt").IntValue; }
Go
exampleStruct, err := driver.Execute(context.Background(), func(txn qldbdriver.Transaction) (interface{}, error) { aStruct := map[string]interface{} { "ExampleString": "Hello World!", "ExampleInt": 256, } // Insertion into QLDB _, err = txn.Execute("UPDATE ExampleTable SET ExampleStruct = ?", aStruct) if err != nil { return nil, err } // Fetching from QLDB result, err := txn.Execute("SELECT VALUE ExampleStruct FROM ExampleTable") if err != nil { return nil, err } // Assume there is only one document in ExampleTable if result.Next(txn) { var decodedResult map[string]interface{} err := ion.Unmarshal(result.GetCurrentData(), &decodedResult) if err != nil { return nil, err } // exampleStruct is now the value fetched from QLDB return decodedResult, nil } return nil, result.Err() })
Node.js
async function queryIonStruct(driver: QldbDriver): Promise<any> { let exampleStruct: any = {stringValue: "Hello World!", intValue: 256}; return (driver.executeLambda(async (txn: TransactionExecutor) => { // Inserting into QLDB await txn.execute("INSERT INTO ExampleTable ?", exampleStruct); // Fetching from QLDB const resultList: dom.Value[] = (await txn.execute("SELECT * FROM ExampleTable")).getResultList(); // Assume there is only one document in ExampleTable const ionValue: dom.Value = resultList[0]; // We can get all the keys of Ion struct and their associated values const ionFieldNames: string[] = ionValue.fieldNames(); // Getting key and value of Ion struct to TypeScript String and Number const nativeStringVal: string = ionValue.get(ionFieldNames[0]).stringValue(); const nativeIntVal: number = ionValue.get(ionFieldNames[1]).numberValue(); // Alternatively, we can access to Ion struct fields, using their literal field names: // const nativeStringVal = ionValue.get("stringValue").stringValue(); // const nativeIntVal = ionValue.get("intValue").numberValue(); exampleStruct = {[ionFieldNames[0]]: nativeStringVal, [ionFieldNames[1]]: nativeIntVal}; return exampleStruct; }) ); }
Python
def update_and_query_ion_struct(txn): # QLDB can take in a Python struct a_struct = {"ExampleString": "Hello world!", "ExampleInt": 256} # Insertion into QLDB txn.execute_statement("UPDATE ExampleTable SET ExampleStruct = ?", a_struct) # Fetching from QLDB cursor = txn.execute_statement("SELECT VALUE ExampleStruct FROM ExampleTable") # Assume there is only one document in ExampleTable for ion_value in cursor: # Ion Python struct is a child class of Python struct a_struct = ion_value # example_struct is now the value fetched from QLDB return a_struct example_struct = driver.execute_lambda(lambda txn: update_and_query_ion_struct(txn))

Valores nulos e tipos dinâmicos

QLDBoferece suporte a conteúdo aberto e não impõe definições de esquema ou tipo de dados para campos de documentos. Você também pode armazenar valores nulos de íons em um QLDB documento. Todos os exemplos anteriores presumem que cada tipo de dados retornado é conhecido e não é nulo. Os exemplos a seguir mostram como trabalhar com o Ion quando o tipo de dados não é conhecido ou é possivelmente nulo.

Java
// Empty variables String exampleString = null; Integer exampleInt = null; // Assume ionValue is some queried data from QLDB IonValue ionValue = null; // Check the value type and assign it to the variable if it is not null if (ionValue.getType() == IonType.STRING) { if (ionValue.isNullValue()) { exampleString = null; } else { exampleString = ((IonString)ionValue).stringValue(); } } else if (ionValue.getType() == IonType.INT) { if (ionValue.isNullValue()) { exampleInt = null; } else { exampleInt = ((IonInt)ionValue).intValue(); } }; // Creating null values IonSystem ionSystem = IonSystemBuilder.standard().build(); // A null value still has an Ion type IonString ionString; if (exampleString == null) { // Specifically a null string ionString = ionSystem.newNullString(); } else { ionString = ionSystem.newString(exampleString); } IonInt ionInt; if (exampleInt == null) { // Specifically a null int ionInt = ionSystem.newNullInt(); } else { ionInt = ionSystem.newInt(exampleInt); } // Special case regarding null! // There is a generic null type which has Ion type 'Null'. // The above null values still have the types 'String' and 'Int' IonValue specialNull = ionSystem.newNull(); if (specialNull.getType() == IonType.NULL) { // This is true! } if (specialNull.isNullValue()) { // This is also true! } if (specialNull.getType() == IonType.STRING || specialNull.getType() == IonType.INT) { // This is false! }
.NET
// Empty variables. string exampleString = null; int? exampleInt = null; // Assume ionValue is some queried data from QLDB. IIonValue ionValue; if (ionValue.Type() == IonType.String) { exampleString = ionValue.StringValue; } else if (ionValue.Type() == IonType.Int) { if (ionValue.IsNull) { exampleInt = null; } else { exampleInt = ionValue.IntValue; } }; // Creating null values. IValueFactory valueFactory = new ValueFactory(); // A null value still has an Ion type. IIonValue ionString = valueFactory.NewString(exampleString); IIonValue ionInt; if (exampleInt == null) { // Specifically a null int. ionInt = valueFactory.NewNullInt(); } else { ionInt = valueFactory.NewInt(exampleInt.Value); } // Special case regarding null! // There is a generic null type which has Ion type 'Null'. IIonValue specialNull = valueFactory.NewNull(); if (specialNull.Type() == IonType.Null) { // This is true! } if (specialNull.IsNull) { // This is also true! }
Go

Limitações de marshalling

Em Go, os valores nil não retêm seu tipo quando você os organiza e depois os desorganiza. Um valor nil é agrupado para Ion null, mas Ion null desagrupa para um valor zero em vez de nil.

ionNull, err := ion.MarshalText(nil) // ionNull is set to ion null if err != nil { return } var result int err = ion.Unmarshal(ionNull, &result) // result unmarshals to 0 if err != nil { return }
Node.js
// Empty variables let exampleString: string; let exampleInt: number; // Assume ionValue is some queried data from QLDB // Check the value type and assign it to the variable if it is not null if (ionValue.getType() === IonTypes.STRING) { if (ionValue.isNull()) { exampleString = null; } else { exampleString = ionValue.stringValue(); } } else if (ionValue.getType() === IonTypes.INT) { if (ionValue.isNull()) { exampleInt = null; } else { exampleInt = ionValue.numberValue(); } } // Creating null values if (exampleString === null) { ionString = dom.load('null.string'); } else { ionString = dom.load.of(exampleString); } if (exampleInt === null) { ionInt = dom.load('null.int'); } else { ionInt = dom.load.of(exampleInt); } // Special case regarding null! // There is a generic null type which has Ion type 'Null'. // The above null values still have the types 'String' and 'Int' specialNull: dom.Value = dom.load("null.null"); if (specialNull.getType() === IonType.NULL) { // This is true! } if (specialNull.getType() === IonType.STRING || specialNull.getType() === IonType.INT) { // This is false! }
Python
# Empty variables example_string = None example_int = None # Assume ion_value is some queried data from QLDB # Check the value type and assign it to the variable if it is not null if ion_value.ion_type == IonType.STRING: if isinstance(ion_value, IonPyNull): example_string = None else: example_string = ion_value elif ion_value.ion_type == IonType.INT: if isinstance(ion_value, IonPyNull): example_int = None else: example_int = ion_value # Creating Ion null values if example_string is None: # Specifically a null string ion_string = loads("null.string") else: # QLDB can take in Python string ion_string = example_string if example_int is None: # Specifically a null int ion_int = loads("null.int") else: # QLDB can take in Python int ion_int = example_int # Special case regarding null! # There is a generic null type which has Ion type 'Null'. # The above null values still have the types 'String' and 'Int' special_null = loads("null.null") if special_null.ion_type == IonType.NULL: # This is true! if special_null.ion_type == IonType.STRING or special_null.ion_type == IonType.INT: # This is false!

Conversão descendente para JSON

Se seu aplicativo exigir JSON compatibilidade, você pode reduzir a conversão dos dados do Amazon Ion em. JSON No entanto, a JSON conversão de íon em causa perdas em certos casos em que seus dados usam os tipos ricos de íons que não existem em. JSON

Para obter detalhes sobre as regras de JSON conversão de íons em, consulte Conversão descendente em JSON no Amazon Ion Cookbook.