Add FilterFieldType

[msfroh]

Description

This class allows developers (in core or plugins) to wrap an existing field type, delegating all behavior by default, overriding specific methods as needed.

See linked issue for more details.

Related Issues

Resolves #17624

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[github-actions]

❌ Gradle check result for 5180b1a: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[kkewwei]

It make sense to me. But it seems not delegate all methods, such as fielddataBuilder. Also it seems don't solve the problem mentioned in #17575, it need the indexedValueForSearch, only if we also support FilterTermBasedFieldType?

[bzhangam]

indexedValueForSearch

indexedValueForSearch will not be directly invoked to process query. It will be invoked through function like termQuery. Since we delegate the termQuery it will use the implementation of indexedValueForSearch of the delegate.

[msfroh]

It make sense to me. But it seems not delegate all methods, such as fielddataBuilder. Also it seems don't solve the problem mentioned in #17575, it need the indexedValueForSearch, only if we also support FilterTermBasedFieldType?

In #17575, it doesn't actually need indexedValueForSearch, since that's internal to the implementation of the delegated field type (since that's a helper used by the various *Query methods).

You're absolutely right about fielddataBuilder -- not sure how I missed that, since I tried overriding all methods from MappedFieldType. I intentionally avoided implementing typeName(), because I believe that the filtered field type should have its own type name.

I'll add a unit test that uses reflection to enforce overrides of all methods to catch mistakes if anyone adds more methods to MappedFieldType.

[navneet1v]

Please add java docs on this class, with some examples on how to use it. This is a good addition in core.

[navneet1v]

should we annotate this with @publicapi?

[github-actions]

❌ Gradle check result for bcd79b6: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

✅ Gradle check result for 3c8423a: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 53 lines in your changes missing coverage. Please review.

Project coverage is 72.46%. Comparing base (6d53f9d) to head (3c8423a).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
...a/org/opensearch/index/mapper/FilterFieldType.java	0.00%	52 Missing ⚠️
...a/org/opensearch/index/mapper/MappedFieldType.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #17627      +/-   ##
============================================
+ Coverage     72.40%   72.46%   +0.06%     
- Complexity    65828    65874      +46     
============================================
  Files          5316     5323       +7     
  Lines        305294   305526     +232     
  Branches      44289    44309      +20     
============================================
+ Hits         221033   221399     +366     
+ Misses        66187    65995     -192     
- Partials      18074    18132      +58     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.