[Copilot]

A global string UseCollation() convention causes snapshots to emit unsupported calls on JSON-mapped complex-collection properties, making the generated C# uncompilable.

• Snapshot generation: Filter collation annotations from complex-collection properties before generating fluent API calls. Preserve collations on ordinary properties.
• Regression coverage: Cover the global convention and nested complex collections, including compilation of generated snapshots.

• Fixes Global UseCollation() convention generates uncompilable model snapshot for JSON-mapped ComplexCollection properties #39406

[Copilot]

🟡 Changes recommended

A moderate-severity finding remains: the snapshot collation filter also drops collations on primitive collections inside complex collections, even though those builders support collation and only regular properties should be filtered.

3 open issues

• Preserve collations on primitive collections inside complex collections · New
• Cover nested complex and primitive collections in snapshot tests · New
• Rename test to reflect omitted collation in snapshot · New

What changed in this PR

This PR fixes a bug where a global UseCollation() convention made the generated model snapshot contain calls that do not compile on JSON-mapped complex collections. The snapshot generator now drops collation for complex-collection properties. Regular properties keep their collation. The PR adds a regression test that builds the generated snapshot and checks the collations that are kept and dropped.

Changes:

• The snapshot generator removes the collation annotation for properties declared in a complex collection.
• A new test covers the global convention on a complex collection and checks that the generated snapshot compiles and keeps collations on ordinary properties.
• An existing test now sets and checks a collation on a complex-collection property, so the omission is covered there too.

File	Description
test/​EFCore.Design.Tests/​Migrations/​Design/​CSharpMigrationsGeneratorTest.ModelSnapshot.cs	Adds a regression test for global collations on complex collections and extends an existing test to check that collations are omitted.
src/​EFCore.Design/​Migrations/​Design/​CSharpSnapshotGenerator.cs	Removes the collation annotation for complex-collection properties so the generated snapshot compiles.

_{Review effort: Lite}

[Copilot]

🔵 Needs a closer look

The new collation filter in the snapshot generator also drops collations from primitive collections inside complex collections, which support them, so those collations would be silently lost from the snapshot and no test covers that path.

No open issues 🎉

1 previously missed issue

In code that hasn't changed since last review

Add snapshot test for collated primitive collections

test/​EFCore.Design.Tests/​Migrations/​Design/​CSharpMigrationsGeneratorTest.ModelSnapshot.cs:6816

The new test only covers a regular string property, so it misses the primitive-collection path changed in src/EFCore.Design/Migrations/Design/CSharpSnapshotGenerator.cs:482-485. Primitive collections inside a complex collection support UseCollation, so the new filter can drop their collation from snapshots and no test fails. Add a test that sets a collation on a primitive collection inside a complex collection and asserts it survives the snapshot round-trip.

3 resolved since last review

• Preserve collations on primitive collections inside complex collections
• Rename test to reflect omitted collation in snapshot
• Cover nested complex and primitive collections in snapshot tests

_{Review effort: Lite}

[github-code-quality]

Code coverage overview

Languages: C#

C# / code-coverage

main ed0b576	copilot/fix-global-u... 4caa4da	+/-
76%	76%	0%

View coverage of the 10 most impacted files.

File	main ed0b576	copilot/fix-global-u... 4caa4da	+/-
src/Shared/NonC...yInitializer.cs	12%	11%	-1%
src/EFCore.Rela...alConnection.cs	93%	93%	0%
src/EFCore.Desi...hotGenerator.cs	99%	99%	0%
src/EFCore.Cosm...erExtensions.cs	100%	100%	0%
src/EFCore.Cosm...erExtensions.cs	46%	46%	0%
src/EFCore.Cosm...peExtensions.cs	73%	73%	0%
src/EFCore.Cosm...StreamHelper.cs	87%	87%	0%
src/EFCore.Cosm...delValidator.cs	98%	98%	0%
src/EFCore.Cosm...orConvention.cs	94%	94%	0%
src/Microsoft.D...nnectionPool.cs	97%	100%	+3%

ℹ️ Calculations represent line coverage. Results may change as calculations are updated.