Class CfnJson

Captures a synthesis-time JSON object a CloudFormation reference which resolves during deployment to the resolved values of the JSON object.

Inheritance

object

CfnJson

Implements

IResolvable

Namespace: Amazon.CDK

Assembly: Amazon.CDK.Lib.dll

Syntax (csharp)

public class CfnJson : Construct, IResolvable

Syntax (vb)

Public Class CfnJson Inherits Construct Implements IResolvable

Remarks

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

Examples

var tagParam = new CfnParameter(this, "TagName");

             var stringEquals = new CfnJson(this, "ConditionJson", new CfnJsonProps {
                 Value = new Dictionary<string, boolean> {
                     { $"aws:PrincipalTag/{tagParam.valueAsString}", true }
                 }
             });

             var principal = new AccountRootPrincipal().WithConditions(new Dictionary<string, object> {
                 { "StringEquals", stringEquals }
             });

             new Role(this, "MyRole", new RoleProps { AssumedBy = principal });

Synopsis

Constructors

CfnJson(Construct, string, ICfnJsonProps)

Captures a synthesis-time JSON object a CloudFormation reference which resolves during deployment to the resolved values of the JSON object.

Properties

CreationStack	The creation stack of this resolvable which will be appended to errors thrown during resolution.
Value	An Fn::GetAtt to the JSON object passed through value and resolved during synthesis.

Methods

Resolve(IResolveContext)	Produce the Token's value at resolution time.
ToJSON()	This is required in case someone JSON.stringifys an object which references this object. Otherwise, we'll get a cyclic JSON reference.

Constructors

CfnJson(Construct, string, ICfnJsonProps)

Captures a synthesis-time JSON object a CloudFormation reference which resolves during deployment to the resolved values of the JSON object.

public CfnJson(Construct scope, string id, ICfnJsonProps props)

Parameters

scope Construct

id string

props ICfnJsonProps

Remarks

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

Examples

var tagParam = new CfnParameter(this, "TagName");

             var stringEquals = new CfnJson(this, "ConditionJson", new CfnJsonProps {
                 Value = new Dictionary<string, boolean> {
                     { $"aws:PrincipalTag/{tagParam.valueAsString}", true }
                 }
             });

             var principal = new AccountRootPrincipal().WithConditions(new Dictionary<string, object> {
                 { "StringEquals", stringEquals }
             });

             new Role(this, "MyRole", new RoleProps { AssumedBy = principal });

Properties

CreationStack

The creation stack of this resolvable which will be appended to errors thrown during resolution.

public virtual string[] CreationStack { get; }

Property Value

string[]

Remarks

This may return an array with a single informational element indicating how to get this property populated, if it was skipped for performance reasons.

Value

An Fn::GetAtt to the JSON object passed through value and resolved during synthesis.

public virtual Reference Value { get; }

Property Value

Reference

Remarks

Normally there is no need to use this property since CfnJson is an IResolvable, so it can be simply used as a value.

Methods

Resolve(IResolveContext)

Produce the Token's value at resolution time.

public virtual object Resolve(IResolveContext context)

Parameters

context IResolveContext

Returns

object

Remarks

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

ToJSON()

This is required in case someone JSON.stringifys an object which references this object. Otherwise, we'll get a cyclic JSON reference.

public virtual string ToJSON()

Returns

string

Remarks

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

Implements

IResolvable