CSHARP-5928: LINQ Provider throws misleading exception if expression translation is not supported#1915
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…translation is not supported
sanych-sun
requested review from
adelinowona,
ajcvickers,
Copilot and
damieng
and removed request for
ajcvickers
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| public static TranslatedExpression TranslateWithoutUnwrapping(TranslationContext context, Expression expression) | ||
| { | ||
| if (!context.HasResultSerializer(expression)) |
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We should not validate it here, because serializer could be missing for different reasons here (it could be either not supported combination of parameters for known-expression, non-translatable expression, or simply not implemented yet expression).
| { | ||
| if (!context.HasResultSerializer(expression)) | ||
| { | ||
| throw new ExpressionNotSupportedException(expression); |
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It does not really matter what we throws here as we will try fallback to expression language on line 45.
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Pull request overview
This PR improves LINQ3 error reporting so that when an expression can’t be translated, the driver throws an ExpressionNotSupportedException that points at the unsupported expression rather than a misleading “couldn’t determine serializer” message.
Changes:
- Added an integration test covering the Jira case (CSHARP-5928) and asserting the unsupported sub-expression appears in the exception message.
- Adjusted filter translation to allow falling back to aggregation-operator translation even when a result serializer can’t be determined up-front.
- Removed the up-front “must have result serializer” guard from aggregation-expression translation and added a targeted serializer validity check in
TranslatedExpression.
Reviewed changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| tests/MongoDB.Driver.Tests/Linq/Linq3Implementation/Jira/CSharp5928Tests.cs | Adds regression test asserting the thrown exception message references the unsupported Replace(...) expression. |
| src/MongoDB.Driver/Linq/Linq3Implementation/Translators/ExpressionToFilterTranslators/ExpressionToFilterTranslator.cs | Moves the “has result serializer” check into the try-path so failures can fall back to aggregation translation. |
| src/MongoDB.Driver/Linq/Linq3Implementation/Translators/ExpressionToAggregationExpressionTranslators/ExpressionToAggregationExpressionTranslator.cs | Removes the up-front serializer guard to avoid masking real translation failures. |
| src/MongoDB.Driver/Linq/Linq3Implementation/Translators/ExpressionToAggregationExpressionTranslators/TranslatedExpression.cs | Validates result serializer isn’t an ignore/unknowable marker before storing it. |
| src/MongoDB.Driver/Linq/Linq3Implementation/Misc/SerializationHelper.cs | Adds EnsureValidResultSerializer helper used by TranslatedExpression. |
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src/MongoDB.Driver/Linq/Linq3Implementation/Misc/SerializationHelper.cs
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