@Generated(value="software.amazon.awssdk:codegen") public final class KeysAndAttributes extends Object implements SdkPojo, Serializable, ToCopyableBuilder<KeysAndAttributes.Builder,KeysAndAttributes>
Represents a set of primary keys and, for each key, the attributes to retrieve from the table.
For each primary key, you must provide all of the key attributes. For example, with a simple primary key, you only need to provide the partition key. For a composite primary key, you must provide both the partition key and the sort key.
Modifier and Type | Class and Description |
---|---|
static interface |
KeysAndAttributes.Builder |
Modifier and Type | Method and Description |
---|---|
List<String> |
attributesToGet()
This is a legacy parameter.
|
static KeysAndAttributes.Builder |
builder() |
Boolean |
consistentRead()
The consistency of a read operation.
|
boolean |
equals(Object obj) |
Map<String,String> |
expressionAttributeNames()
One or more substitution tokens for attribute names in an expression.
|
<T> Optional<T> |
getValueForField(String fieldName,
Class<T> clazz) |
int |
hashCode() |
List<Map<String,AttributeValue>> |
keys()
The primary key attribute values that define the items and the attributes associated with the items.
|
String |
projectionExpression()
A string that identifies one or more attributes to retrieve from the table.
|
List<SdkField<?>> |
sdkFields() |
static Class<? extends KeysAndAttributes.Builder> |
serializableBuilderClass() |
KeysAndAttributes.Builder |
toBuilder() |
String |
toString()
Returns a string representation of this object.
|
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
copy
public List<Map<String,AttributeValue>> keys()
The primary key attribute values that define the items and the attributes associated with the items.
Attempts to modify the collection returned by this method will result in an UnsupportedOperationException.
public List<String> attributesToGet()
This is a legacy parameter. Use ProjectionExpression
instead. For more information, see Legacy
Conditional Parameters in the Amazon DynamoDB Developer Guide.
Attempts to modify the collection returned by this method will result in an UnsupportedOperationException.
ProjectionExpression
instead. For more information, see
Legacy Conditional Parameters in the Amazon DynamoDB Developer Guide.public Boolean consistentRead()
The consistency of a read operation. If set to true
, then a strongly consistent read is used;
otherwise, an eventually consistent read is used.
true
, then a strongly consistent read is
used; otherwise, an eventually consistent read is used.public String projectionExpression()
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 ProjectionExpression
must be separated
by commas.
If no attribute names are specified, then all attributes will be returned. If any of the requested attributes are not found, they will not appear in the result.
For more information, see Accessing Item Attributes in the Amazon DynamoDB Developer Guide.
ProjectionExpression
must be separated by commas.
If no attribute names are specified, then all attributes will be returned. If any of the requested attributes are not found, they will not appear in the result.
For more information, see Accessing Item Attributes in the Amazon DynamoDB Developer Guide.
public Map<String,String> expressionAttributeNames()
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
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 Accessing Item Attributes in the Amazon DynamoDB Developer Guide.
Attempts to modify the collection returned by this method will result in an UnsupportedOperationException.
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
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 Accessing Item Attributes in the Amazon DynamoDB Developer Guide.
public KeysAndAttributes.Builder toBuilder()
toBuilder
in interface ToCopyableBuilder<KeysAndAttributes.Builder,KeysAndAttributes>
public static KeysAndAttributes.Builder builder()
public static Class<? extends KeysAndAttributes.Builder> serializableBuilderClass()
public String toString()
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