fix: close LINQ Where predicate-translation gaps#124
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Negation (`!`) in a Where predicate was silently dropped, producing the opposite filter. Override VisitUnary to wrap the operand in a `not.` filter, and fix PrepareFilter to serialize negated groups as `not.and=(...)` / `not.or=(...)`.
`Where(x => ids.Contains(x.Col))` previously threw instead of producing a Postgrest `in` filter. VisitMethodCall now classifies Contains by which side references the model: a column containing a constant keeps the cs/like translation, while a captured collection containing a column becomes `in`. Handles instance, static Enumerable, and span-based MemoryExtensions.Contains; ambiguous shapes throw a descriptive error.
`Where(x => x.IsActive)` and `Where(x => !x.IsActive)` threw "Unable to parse the supplied predicate" because the visitor only built filters from binary and method-call expressions. VisitMember now translates a boolean column that references the model into `column.eq.true`, working as a bare body, inside &&/|| groups, and negated (via the existing not. wrapping).
`Where(x => x.StartDate < x.EndDate)` crashed with a cryptic "variable 'x' ... not defined" because the visitor tried to evaluate the right-hand column as a local value. VisitBinary now detects a right side that references the model and throws an ArgumentException explaining that Postgrest has no column-to-column filter, suggesting a computed column or RPC instead.
spydon
approved these changes
Jul 9, 2026
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Follow-up to #122.
WhereExpressionVisitormishandled several common LINQWherepredicate shapes: one produced incorrect results, two threw non-descriptive errors, and one was unsupported. Each is addressed in its own commit, developed test-first againstGenerateUrl()/exception assertions, with theWhereXML documentation updated to describe supported and unsupported shapes.Where(x => !(x.Name == "foo"))generatedname=eq.foo— the inverse of the intended filter — which also affectedUpdate/Deletecalls using the same predicate. Negation is now translated to anot.filter.PrepareFilteris also corrected so a negated logical group serializes asnot.and=(...), which additionally fixes the public.Not()API for group filters.Containsis translated toin.Where(x => ids.Contains(x.Id))previously threw rather than producing aninfilter. InstanceList.Contains, staticEnumerable.Contains, and the span-basedMemoryExtensions.Containsused for arrays on modern .NET are all supported.Where(x => x.IsActive)andWhere(x => !x.IsActive)previously threw "Unable to parse"; they now translate toeqandnot.eq.Where(x => x.Start < x.End)previously failed withvariable 'x' not defined. PostgREST filters compare a column to a literal value and cannot express a column-to-column comparison, so this now throws anArgumentExceptionrecommending a computed/generated column or an RPC.All new tests assert on
GenerateUrl()and require no network access; the full LINQ unit suite and theTestLinqWhereintegration test pass.