CfnJson¶
-
class
aws_cdk.core.
CfnJson
(scope, id, *, value)¶ Bases:
aws_cdk.core.Construct
Captures a synthesis-time JSON object a CloudFormation reference which resolves during deployment to the resolved values of the JSON object.
The main use case for this is to overcome a limitation in CloudFormation that does not allow using intrinsic functions as dictionary keys (because dictionary keys in JSON must be strings). Specifically this is common in IAM conditions such as
StringEquals: { lhs: "rhs" }
where you want “lhs” to be a reference.This object is resolvable, so it can be used as a value.
This construct is backed by a custom resource.
- ExampleMetadata
infused
Example:
tag_param = CfnParameter(self, "TagName") string_equals = CfnJson(self, "ConditionJson", value={ "f"aws:PrincipalTag/{tagParam.valueAsString}"": True } ) principal = iam.AccountRootPrincipal().with_conditions({ "StringEquals": string_equals }) iam.Role(self, "MyRole", assumed_by=principal)
- Parameters
scope (
Construct
) –id (
str
) –value (
Any
) – The value to resolve. Can be any JavaScript object, including tokens and references in keys or values.
Methods
-
resolve
(_)¶ Produce the Token’s value at resolution time.
- Parameters
_ –
- Return type
Any
-
to_json
()¶ This is required in case someone JSON.stringifys an object which refrences this object. Otherwise, we’ll get a cyclic JSON reference.
- Return type
str
-
to_string
()¶ Returns a string representation of this construct.
- Return type
str
Attributes
-
creation_stack
¶ The creation stack of this resolvable which will be appended to errors thrown during resolution.
This may return an array with a single informational element indicating how to get this property populated, if it was skipped for performance reasons.
- Return type
List
[str
]
-
node
¶ The construct tree node associated with this construct.
- Return type
-
value
¶ An Fn::GetAtt to the JSON object passed through
value
and resolved during synthesis.Normally there is no need to use this property since
CfnJson
is an IResolvable, so it can be simply used as a value.- Return type
Static Methods
-
classmethod
is_construct
(x)¶ Return whether the given object is a Construct.
- Parameters
x (
Any
) –- Return type
bool