[paulb777]

Fixes #14137
Fixes #8286

Problem

getData applied its result with applyServerOverwriteAtPath: at the query's location, even for a query with a limit or range. That result is only part of the data at the location, so the overwrite replaced:

• the data of other listeners at the location, which were refiltered against the partial data. In Realtime Database: Database listener clears children when performing another query in same ref #14137, a queryStartingAtValue: listener lost all its children after a queryEndingBeforeValue: + queryLimitedToLast: get. In Possible bug in “queryOrdered(byChild:).queryEqual(toValue:).getData" function #8286, a listener without a filter fired again with only the child that a queryEqualToValue: get returned.
• the data of listeners below the location whose children weren't in the result.
• the persisted server cache at the location, which kept only the partial data.

Fix

FRepo getData: now calls a new -[FSyncTree applyGetResultForQuery:newData:]. For a query that loads all data, it still applies a server overwrite. For any other query, it applies the result the way the JS SDK's repoGetValue does:

1. Add a registration for the query without starting a listen, so the query has a view and a tag.
2. Apply the result as a tagged overwrite. This only updates that view, and it merges into the persisted cache.
3. Remove the registration without stopping a listen. This also removes the tag.

The registration is a new FKeepSyncedEventRegistration instance. It raises no events and only matches itself, so an existing listener or keepSynced registration on the same query stays in place and gets the result.

addEventRegistration: and removeEventRegistration: get private variants with skipListenerSetup and skipListenerDedup flags, like the JS SDK's skipSetupListener and skipListenerDedup.

This is separate from #12168, which #16721 fixes. Thanks to @diegogarciar and @fawzialrifai for the reports.

Testing

• 7 new unit tests in FSyncPointTests.m for applyGetResultForQuery:newData:. These 4 fail without the fix:

  • a filtered view at the same location keeps its data
  • a view without a filter at the same location keeps its data
  • a view below the location keeps its data
  • the persisted server cache keeps the data that isn't in the result

  The other 3 check that a get starts and stops no listens and leaves no tag, keeps a keepSynced query synced, and raises events for a listener on the same query.

• 4 new integration tests in FIRDatabaseQueryTests.m for the same 4 cases. All 4 fail without the fix.

• DatabaseUnit (SPM, macOS): 436 tests pass.

• FIRDatabaseQueryTests, FKeepSyncedTest and FPersist integration tests, against the RTDB emulator: 139/139 pass.

• Merged with fix(database): resend in-flight gets after reconnect #16719, fix(database): avoid crash on get error without reason #16720 and fix(database): return child data from getData under observed parent #16721, only CHANGELOG.md conflicts. The first commit of this PR also passed the unit and integration tests in that merge (447 and 140 tests).

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[paulb777]

/gemini review

[gemini-code-assist]

Code Review

This pull request fixes an issue where calling getData on a query with a limit or range could incorrectly remove data from other listeners at or below the query's location, as well as from the disk cache. It introduces applyGetResultForQuery:newData: in FSyncTree to apply the query result specifically to the query's own view without setting up a persistent listen or triggering unnecessary listener changes. This is achieved by adding helper methods to skip listener setup and deduplication during registration and removal. Comprehensive integration and unit tests have been added to verify this behavior. There are no review comments, so I have no feedback to provide.

[paulb777]

/gemini review

[gemini-code-assist]

Code Review

This pull request addresses an issue where calling getData on a query with a limit or range could incorrectly remove data from other listeners at or below the query's location, as well as from the disk cache. To resolve this, the changes introduce applyGetResultForQuery:newData: in FSyncTree to apply the query result specifically to its own view without triggering a full server overwrite, utilizing temporary event registrations that skip listener setup and deduplication. Comprehensive integration and unit tests have been added to verify this behavior. There are no review comments, so I have no additional feedback to provide.