適用於 Xamarin 的 AWS Mobile SDK 現在已包含在 中 適用於 .NET 的 AWS SDK。本指南參考 Mobile SDK for Xamarin 的封存版本。

本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

# 使用文件模型
<a name="dynamodb-integration-docmodel"></a>

文件模型提供低階 .NET API 的包裝函式類別。資料表和文件是金鑰包裝函式類別。您可以使用文件模型來建立、擷取、更新和刪除項目。若要建立、更新和刪除資料表，您必須使用低階 API。如需如何使用低階 API 的說明，請參閱[使用 DynamoDB 服務層級 APIs](dynamodb-integration-lowlevelapi.md)。Amazon.DynamoDB.DocumentModel 命名空間提供低階 API。

若要進一步了解文件模型，請參閱 [.NET 文件模型](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DotNetSDKMidLevel.html)。

## 建立 DynamoDB 用戶端
<a name="create-a-dynamodb-client"></a>

若要建立 DynamoDB 用戶端：

```
var client = new AmazonDynamoDBClient(credentials,region);
DynamoDBContext context = new DynamoDBContext(client);
```

## CRUD 操作
<a name="crud-operations"></a>

### 儲存項目
<a name="save-an-item"></a>

建立項目：

```
Table table = Table.LoadTable(client, "Books");
id = Guid.NewGuid().ToString();
var books = new Document();
books["Id"] = id;
books["Author"] = "Mark Twain";
books["Title"] = "Adventures of Huckleberry Finn";
books["ISBN"] = "112-111111";
books["Price"] = "10";
```

將項目儲存至 DynamoDB 資料表：

```
var book = await table.PutItemAsync(books);
```

### 擷取項目
<a name="retrieve-an-item"></a>

若要擷取項目：

```
public async Task GetItemAsync(AWSCredentials credentials, RegionEndpoint region)
{
      var client = new AmazonDynamoDBClient(credentials, region);
      Table books = Table.LoadTable(client, "Books");
      var book = await books.GetItemAsync(id);
}
```

### 更新項目
<a name="update-an-item"></a>

若要更新項目：

```
public async Task UpdateItemAttributesAsync(AWSCredentials credentials, RegionEndpoint region)
{
      var book = new Document();
      book["Id"] = id;
      book["PageCount"] = "200";
      var client = new AmazonDynamoDBClient(credentials, region);
      Table books = Table.LoadTable(client, "Books");
      Document updatedBook = await books.UpdateItemAsync(book);
}
```

若要依條件更新項目：

```
public async Task UpdateItemConditionallyAsync(AWSCredentials credentials, RegionEndpoint region) {
      var book = new Document();
      book["Id"] = id;
      book["Price"] = "30";

      // For conditional price update, creating a condition expression.
      Expression expr = new Expression();
      expr.ExpressionStatement = "Price = :val";
      expr.ExpressionAttributeValues[":val"] = 10.00;

      var client = new AmazonDynamoDBClient(credentials, region);
      Table books = Table.LoadTable(client, "Books");

      Document updatedBook = await books.UpdateItemAsync(book);
}
```

### 刪除項目
<a name="delete-an-item"></a>

若要刪除項目：

```
public async Task DeleteItemAsync(AWSCredentials credentials, RegionEndpoint region)
{
  var client = new AmazonDynamoDBClient(credentials, region);
  Table books = Table.LoadTable(client, "Books");
  await books.DeleteItemAsync(id);
}
```

### 查詢和掃描
<a name="query-and-scan"></a>

若要查詢和擷取作者為「Mark Twain」的所有書籍：

```
public async Task QueryAsync(AWSCredentials credentials, RegionEndpoint region) {
  var client = new AmazonDynamoDBClient(credentials, region);
  Table books = Table.LoadTable(client, "Books");
  var search = books.Query(new QueryOperationConfig() {
   IndexName = "Author-Title-index",
   Filter = new QueryFilter("Author", QueryOperator.Equal, "Mark Twain")
  });
  Console.WriteLine("ScanAsync: printing query response");
  var documents = await search.GetRemainingAsync();
  documents.ForEach((d) = > {
   PrintDocument(d);
  });
}
```

下面的掃描範例程式碼會傳回我們資料表中的所有書籍：

```
public async Task ScanAsync(AWSCredentials credentials, RegionEndpoint region) {
      var client = new AmazonDynamoDBClient(credentials, region);
      Table books = Table.LoadTable(client, "Books");
      var search = books.Scan(new ScanOperationConfig() {
              ConsistentRead = true
      });
      Console.WriteLine("ScanAsync: printing scan response");
      var documents = await search.GetRemainingAsync();
      documents.ForEach((d) = > {
              PrintDocument(d);
      });
}
```