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DynamoDB  >  Operations  >  get_item

get_item

Operation

get_item async 

get_item(input: GetItemInput, plugins: list[Plugin] | None = None) -> GetItemOutput

The GetItem operation returns a set of attributes for the item with the given primary key. If there is no matching item, GetItem does not return any data and there will be no Item element in the response.

GetItem provides an eventually consistent read by default. If your application requires a strongly consistent read, set ConsistentRead to true. Although a strongly consistent read might take more time than an eventually consistent read, it always returns the last updated value.

Parameters:

Name Type Description Default
input GetItemInput

An instance of GetItemInput.

 required
plugins list[Plugin] | None

A list of callables that modify the configuration dynamically. Changes made by these plugins only apply for the duration of the operation execution and will not affect any other operation invocations.

 None

Returns:

Type Description
GetItemOutput

An instance of GetItemOutput.

Input

GetItemInput dataclass

Represents the input of a GetItem operation.

Attributes

attributes_to_get class-attribute instance-attribute 
attributes_to_get: list[str] | None = None

This is a legacy parameter. Use ProjectionExpression instead. For more information, see AttributesToGet in the Amazon DynamoDB Developer Guide.

consistent_read class-attribute instance-attribute 
consistent_read: bool | None = None

Determines the read consistency model: If set to true, then the operation uses strongly consistent reads; otherwise, the operation uses eventually consistent reads.

expression_attribute_names class-attribute instance-attribute 
expression_attribute_names: dict[str, str] | None = None

One or more substitution tokens for attribute names in an expression. The following are some use cases for using ExpressionAttributeNames:

  • To access an attribute whose name conflicts with a DynamoDB reserved word.

  • To create a placeholder for repeating occurrences of an attribute name in an expression.

  • To prevent special characters in an attribute name from being misinterpreted in an expression.

Use the # character in an expression to dereference an attribute name. For example, consider the following attribute name:

  • Percentile

The name of this attribute conflicts with a reserved word, so it cannot be used directly in an expression. (For the complete list of reserved words, see Reserved Words in the Amazon DynamoDB Developer Guide). To work around this, you could specify the following for ExpressionAttributeNames:

  • {"#P":"Percentile"}

You could then use this substitution in an expression, as in this example:

  • #P = :val
Note

Tokens that begin with the : character are expression attribute values, which are placeholders for the actual value at runtime.

For more information on expression attribute names, see Specifying Item Attributes in the Amazon DynamoDB Developer Guide.

key class-attribute instance-attribute 
key: dict[str, AttributeValue] | None = None

A map of attribute names to AttributeValue objects, representing the primary key of the item to retrieve.

For the primary key, you must provide all of the attributes. For example, with a simple primary key, you only need to provide a value for the partition key. For a composite primary key, you must provide values for both the partition key and the sort key.

projection_expression class-attribute instance-attribute 
projection_expression: str | None = None

A string that identifies one or more attributes to retrieve from the table. These attributes can include scalars, sets, or elements of a JSON document. The attributes in the expression must be separated by commas.

If no attribute names are specified, then all attributes are returned. If any of the requested attributes are not found, they do not appear in the result.

For more information, see Specifying Item Attributes in the Amazon DynamoDB Developer Guide.

return_consumed_capacity class-attribute instance-attribute 
return_consumed_capacity: ReturnConsumedCapacity | None = None

Determines the level of detail about either provisioned or on-demand throughput consumption that is returned in the response:

  • INDEXES - The response includes the aggregate ConsumedCapacity for the operation, together with ConsumedCapacity for each table and secondary index that was accessed.

Note that some operations, such as GetItem and BatchGetItem, do not access any indexes at all. In these cases, specifying INDEXES will only return ConsumedCapacity information for table(s).

  • TOTAL - The response includes only the aggregate ConsumedCapacity for the operation.

  • NONE - No ConsumedCapacity details are included in the response.

table_name class-attribute instance-attribute 
table_name: str | None = None

The name of the table containing the requested item. You can also provide the Amazon Resource Name (ARN) of the table in this parameter.

Output

GetItemOutput dataclass

Represents the output of a GetItem operation.

Attributes

consumed_capacity class-attribute instance-attribute 
consumed_capacity: ConsumedCapacity | None = None

The capacity units consumed by the GetItem operation. The data returned includes the total provisioned throughput consumed, along with statistics for the table and any indexes involved in the operation. ConsumedCapacity is only returned if the ReturnConsumedCapacity parameter was specified. For more information, see Capacity unit consumption for read operations in the Amazon DynamoDB Developer Guide.

item class-attribute instance-attribute 
item: dict[str, AttributeValue] | None = None

A map of attribute names to AttributeValue objects, as specified by ProjectionExpression.