Add Android Record Module #227

eranl · 2023-10-27T22:15:44Z

Add a module that allows deserialization into records using the canonical constructor on Android, where java records are supported through desugaring, and Jackson's built-in support for records doesn't work, since the desugared classes have a non-standard super class, and record component-related reflection methods are missing.

See Android Developers Blog article

Note: the canonical record constructor is found through matching of parameter types with field types. Therefore, this module doesn't allow a deserialized desugared record class to have a custom
constructor with a signature that's any permutation of the canonical one's.

See FasterXML/jackson-databind#4166

This is the simplest implementation I could make. Please let me know if I should handle more cases.

android-record/pom.xml

pjfanning

Could you use the animal sniffer maven plugin to ensure that we support a specific Android SDK version? It would be useful to set the android version to the lowest one that works - so that we can document the minimum supported Android SDK version.

See https://github.com/FasterXML/jackson-core/blob/2.16/pom.xml - jackson-core tests that we support Android SDK version 26.

https://www.mojohaus.org/animal-sniffer/animal-sniffer-maven-plugin/

…comments

eranl · 2023-10-28T00:29:06Z

Could you use the animal sniffer maven plugin to ensure that we support a specific Android SDK version? It would be useful to set the android version to the lowest one that works - so that we can document the minimum supported Android SDK version.

See https://github.com/FasterXML/jackson-core/blob/2.16/pom.xml - jackson-core tests that we support Android SDK version 26.

https://www.mojohaus.org/animal-sniffer/animal-sniffer-maven-plugin/

Done. I put the version settings in the main POM file. Is that correct?
Also, there's no point in using a lower Android SDK version than 26, right?

android-record/src/moditect/module-info.java

cowtowncoder · 2023-10-28T01:36:25Z

...oid-record/src/main/java/com/fasterxml/jackson/module/androidrecord/AndroidRecordModule.java

+                          .constructType(parameter.getParameterizedType()), null, null, null, null, i, null, null);
+        }
+
+        ((StdValueInstantiator) defaultInstantiator).configureFromObjectSettings(null, null, null, null,


This looks dangerous... having mostly nulls, and overwriting internal state.
Ideally I'd rather create a new instance (even if of type StdValueInstantiator) instead of forcibly trying to modify passed-in instantiator

I've improved the Property construction code. Please take a look.
Regarding modifying the instantiator, I followed this example. Should I use a different pattern?

Will do. I think that usage pattern is probably fine -- will add a comment if I remember reasons to use different approach.

...oid-record/src/main/java/com/fasterxml/jackson/module/androidrecord/AndroidRecordModule.java

With the goal of maximizing consistency with built-in record support, I copied and "desugared" some unit tests from https://github.com/FasterXML/jackson-databind/tree/2.16/src/test-jdk17/java/com/fasterxml/jackson/databind/records. A few of the test cases are failing, and I marked them with a "Failing" comment and a "notest" name prefix. I'm hoping for guidance about whether and how I should fix them. Fixed handling of getters Added support for injected values Added use of constructor parameter names Skip module if class already has a withArgsCreator

eranl · 2023-11-03T01:09:04Z

With the goal of maximizing consistency with built-in record support, I copied and "desugared" some unit tests from jackson-databind. A few of the test cases are failing, and I marked them with a "Failing" comment and a "notest" name prefix. I'm hoping for guidance about whether and how I should fix them.
Also, should I copy all of the tests from that package?

cowtowncoder · 2023-11-04T03:03:55Z

With the goal of maximizing consistency with built-in record support, I copied and "desugared" some unit tests from jackson-databind. A few of the test cases are failing, and I marked them with a "Failing" comment and a "notest" name prefix. I'm hoping for guidance about whether and how I should fix them. Also, should I copy all of the tests from that package?

That sounds good. I don't think you necessarily need to copy all tests, although I guess number of tests is not huge in grand scheme of things. It's just that there's then extra maintenance needed.

cowtowncoder · 2023-11-04T03:07:38Z

Ok I will try to go over code again; I like how things are developing and my only concern is wrt 2.16.0 release whether we can make this ready to go in.

But in the meantime one thing that I will need to merge is CLA (assuming you haven't sent one earlier @eranl ?).
This is only needed once for any and all Jackson contributions; it's from here:

https://github.com/FasterXML/jackson/blob/master/contributor-agreement.pdf

and the usual way is to print, fill & sign, scan/photo, email to cla at fasterxml dot com.
Once this is done PR may be merged, assuming everything else is ready.

Looking forward to merging this & once again thank you for contributing it @eranl !

eranl · 2023-11-06T00:41:15Z

With the goal of maximizing consistency with built-in record support, I copied and "desugared" some unit tests from jackson-databind. A few of the test cases are failing, and I marked them with a "Failing" comment and a "notest" name prefix. I'm hoping for guidance about whether and how I should fix them. Also, should I copy all of the tests from that package?

That sounds good. I don't think you necessarily need to copy all tests, although I guess number of tests is not huge in grand scheme of things. It's just that there's then extra maintenance needed.

What should I do about the failing tests? Fix them (I'd need guidance on that)? Delete them? Move them to a failing package?

eranl · 2023-11-06T00:43:09Z

Could you use the animal sniffer maven plugin to ensure that we support a specific Android SDK version? It would be useful to set the android version to the lowest one that works - so that we can document the minimum supported Android SDK version.
See https://github.com/FasterXML/jackson-core/blob/2.16/pom.xml - jackson-core tests that we support Android SDK version 26.
https://www.mojohaus.org/animal-sniffer/animal-sniffer-maven-plugin/

Done. I put the version settings in the main POM file. Is that correct? Also, there's no point in using a lower Android SDK version than 26, right?

Is this ok?

android-record/pom.xml

cowtowncoder · 2023-11-08T03:02:04Z

...oid-record/src/main/java/com/fasterxml/jackson/module/androidrecord/AndroidRecordModule.java

+  public void setupModule(SetupContext context) {
+    super.setupModule(context);
+    context.addValueInstantiators(AndroidRecordModule::findValueInstantiator);
+    context.setClassIntrospector(new AndroidRecordClassIntrospector());


Hmmmmh. This is somewhat problematic as it does not compose; ideally Modules wouldn't have to override it, as only one module can really change it (others would override it).

I'll need to think about this a bit: I can see why this is necessary here, and how it otherwise is quite elegant approach. Just sub-classing part is challenging wrt (lack of) composeability.

Does that mean that my statement in the doc that "this module is a no-op when no Android-desugared records are being (de)serialized" is not accurate anymore? That is problematic.

Only if some other module tries to override ClassIntrospector -- it is not problem if this is the only module to do so.
So unlike, say, AnnotationIntrospectors that can be chained, there's no existing mechanism to combine ClassIntrospectors

How common is it for modules to do that? Should I document this limitation?
Also, can/should I implement a ClassIntrospector chaining feature?

@eranl It might be best to add something in README to mention this.
I don't remember any other module overriding it, so this is theoretical problem, not actual one.
(at least wrt modules under FasterXML)

On chaining... I thought about that, but in general I'm not sure how commonly this is needed etc.
Due to timing it needs to wait until 2.17 (that is, post 2.16.0 and cannot go in a patch) so there's no hurry.
So what I am thinking is that for 2.17 we could consider various approaches to remove this problem; and not have to make last minute changes that may turn out problematic.

@eranl It might be best to add something in README to mention this. I don't remember any other module overriding it, so this is theoretical problem, not actual one. (at least wrt modules under FasterXML)

Done. see #230.

On chaining... I thought about that, but in general I'm not sure how commonly this is needed etc. Due to timing it needs to wait until 2.17 (that is, post 2.16.0 and cannot go in a patch) so there's no hurry. So what I am thinking is that for 2.17 we could consider various approaches to remove this problem; and not have to make last minute changes that may turn out problematic.

Sure, I meant in a future version. Please let me know when is a good time, and what's your preferred approach.

...oid-record/src/main/java/com/fasterxml/jackson/module/androidrecord/AndroidRecordModule.java

cowtowncoder · 2023-11-09T05:23:34Z

@eranl I think that due to timing constraints -- I really need to get this merged ASAP, if it is to make it in 2.16.0! -- I am ok with the implementation as is; we can tackle some changes in 2.17.
And as I said, implementation is mostly fine anyway.

But one thing that must occur before I can merge this is the CLA (see my earlier comment).
If at all possible, it'd be great if you could get that sent so I can proceed with merging.

As to failing tests; yes, moving them under src/test/java/.../failing would make sense (if not already moved), until issues can be resolved.
It may also make sense to trim BaseTest and BaseMapTest to only include methods actually needed. But that's icing on the cake.
One challenge is that I need to merge 2.x branch into 3.0 (master); that's some effort although mostly mechanical (different Java package, Maven artifact, module name).

Moved failing tests to 'failing' package. Added test for differing generic parameter types. Pruned BaseTest and BaseMapTest. Added comment about '-parameters' compiler option.

eranl · 2023-11-09T18:40:36Z

But one thing that must occur before I can merge this is the CLA (see my earlier comment). If at all possible, it'd be great if you could get that sent so I can proceed with merging.

Sent.

As to failing tests; yes, moving them under src/test/java/.../failing would make sense (if not already moved), until issues can be resolved.

Done.

It may also make sense to trim BaseTest and BaseMapTest to only include methods actually needed. But that's icing on the cake.

Done.

cowtowncoder · 2023-11-09T19:30:27Z

android-record/pom.xml

+        <inherited>true</inherited>
+        <configuration>
+          <compilerArgs>
+            <!-- Module uses constructor parameter names (and types) to identify the canonical constructor -->


Ah. Because unlike Records there's no specified metadata to fix ordering, so names need to be used.

Right. I've been wondering if I should document this requirement, but based on my local testing, it seems that the android build system always stores parameter names for desugared record canonical constructors in class files, at least with SDK 34.

Added note to doc in #230.

Thank you @eranl --merged!

cowtowncoder · 2023-11-10T00:39:48Z

@eranl My apologies: I don't think we have cla at fasterxml dot com alias -- I'll try to set up one, but in the meantime, could you re-send CLA to info at fasterxml dot com instead.
Apologies for the mix up here.

eranl · 2023-11-10T01:59:20Z

@eranl My apologies: I don't think we have cla at fasterxml dot com alias -- I'll try to set up one, but in the meantime, could you re-send CLA to info at fasterxml dot com instead. Apologies for the mix up here.

Sent.

Add Android Record Module

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Updated doc.

cc269c5

Moved failing tests to 'failing' package. Added test for differing generic parameter types. Pruned BaseTest and BaseMapTest. Added comment about '-parameters' compiler option.

cowtowncoder reviewed Nov 9, 2023

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cowtowncoder merged commit 40ec12c into FasterXML:2.16 Nov 10, 2023
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cowtowncoder added a commit that referenced this pull request Nov 10, 2023

Update release notes wrt #227

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cowtowncoder added the 2.16 label Nov 10, 2023

This was referenced Nov 11, 2023

Feature request: registering subtypes without annotating the parent class FasterXML/jackson-databind#2104

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Add Android Record Module #227

Add Android Record Module #227

eranl commented Oct 27, 2023

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Add Android Record Module #227

Add Android Record Module #227

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