Struct aws_sdk_dynamodb::model::KeysAndAttributes
source · [−]#[non_exhaustive]pub struct KeysAndAttributes {
pub keys: Option<Vec<HashMap<String, AttributeValue>>>,
pub attributes_to_get: Option<Vec<String>>,
pub consistent_read: Option<bool>,
pub projection_expression: Option<String>,
pub expression_attribute_names: Option<HashMap<String, String>>,
}
Expand description
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.
Fields (Non-exhaustive)
This struct is marked as non-exhaustive
Struct { .. }
syntax; cannot be matched against without a wildcard ..
; and struct update syntax will not work.keys: Option<Vec<HashMap<String, AttributeValue>>>
The primary key attribute values that define the items and the attributes associated with the items.
attributes_to_get: Option<Vec<String>>
This is a legacy parameter. Use ProjectionExpression
instead. For more information, see Legacy Conditional Parameters in the Amazon DynamoDB Developer Guide.
consistent_read: Option<bool>
The consistency of a read operation. If set to true
, then a strongly consistent read is used; otherwise, an eventually consistent read is used.
projection_expression: Option<String>
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.
expression_attribute_names: Option<HashMap<String, String>>
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.
Implementations
The primary key attribute values that define the items and the attributes associated with the items.
This is a legacy parameter. Use ProjectionExpression
instead. For more information, see Legacy Conditional Parameters in the Amazon DynamoDB Developer Guide.
The consistency of a read operation. If set to true
, then a strongly consistent read is used; otherwise, an eventually consistent read is used.
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.
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.
Creates a new builder-style object to manufacture KeysAndAttributes
Trait Implementations
This method tests for self
and other
values to be equal, and is used
by ==
. Read more
This method tests for !=
.
Auto Trait Implementations
impl RefUnwindSafe for KeysAndAttributes
impl Send for KeysAndAttributes
impl Sync for KeysAndAttributes
impl Unpin for KeysAndAttributes
impl UnwindSafe for KeysAndAttributes
Blanket Implementations
Mutably borrows from an owned value. Read more
Attaches the provided Subscriber
to this type, returning a
WithDispatch
wrapper. Read more
Attaches the current default Subscriber
to this type, returning a
WithDispatch
wrapper. Read more