fix(kernel): Correct null handling in JSON types #523
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The serialization of structs creates a jackson ObjectNode to pass down to the serialization layer, however those are turned to JSON without processing and are not honoring the inclusion setting to ignore nulls. Added some code in the Java generator to stop adding null values into the ObjectNode.
RomainMuller
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rix0rrr
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There are a couple of places where fields accept values that are typed as `Json` per the JSII type specification. This conveys that literal `null` values may be passed and need to be preserved (as far as JSII is concerned - see aws/jsii#523). However in the CloudFormation domain, `null` is semantically equivalent to `undefined`. Now enters Javascript's confusing type system, where `null` is an `object` that cannot be converted to `object` (you read this correctly): ```js typeof null === 'object' // => true Object.entries(null); // => Thrown: // TypeError: Cannot convert undefined or null to object // at Function.entries (<anonymous>) ``` So this changes the `undefined` checks to the `null`-coercing way, so that `null` and `undefined` are handled the same way.
RomainMuller
added a commit
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that referenced
this pull request
Jun 7, 2019
There are a couple of places where fields accept values that are typed as `Json` per the JSII type specification. This conveys that literal `null` values may be passed and need to be preserved (as far as JSII is concerned - see aws/jsii#523). However in the CloudFormation domain, `null` is semantically equivalent to `undefined`. Now enters Javascript's confusing type system, where `null` is an `object` that cannot be converted to `object` (you read this correctly): ```js typeof null === 'object' // => true Object.entries(null); // => Thrown: // TypeError: Cannot convert undefined or null to object // at Function.entries (<anonymous>) ``` So this changes the `undefined` checks to the `null`-coercing way, so that `null` and `undefined` are handled the same way.
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rix0rrr
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to aws/aws-cdk
that referenced
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Jun 7, 2019
There are a couple of places where fields accept values that are typed as `Json` per the JSII type specification. This conveys that literal `null` values may be passed and need to be preserved (as far as JSII is concerned - see aws/jsii#523). However in the CloudFormation domain, `null` is semantically equivalent to `undefined`. Now enters Javascript's confusing type system, where `null` is an `object` that cannot be converted to `object` (you read this correctly): ```js typeof null === 'object' // => true Object.entries(null); // => Thrown: // TypeError: Cannot convert undefined or null to object // at Function.entries (<canonymous>) ``` So this changes the `undefined` checks to the `null`-coercing way, so that `null` and `undefined` are handled the same way.
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The JSON types were serialized "as-is" without touch, meaning if the
value was
null, it would be forwarded asnull, instead ofundefined.This caused some CDK usage patterns to crash at runtime. This changes
the behavior so that top-level
nulls in JSON types turn intoundefined,while
nulls nested in the JSON value will be preserved (they are validJSON after all!).
Additionally, tuned the Java code generator a little:
The serialization of structs creates a jackson ObjectNode to pass down
to the serialization layer, however those are turned to JSON without
processing and are not honoring the inclusion setting to ignore nulls.
Added some code in the Java generator to stop adding null values into
the ObjectNode.
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.