(MINOR): Reference query values through the query object so ORMs parameterize them

[PaulTrampert]

Why

Every attribute built its query value with Expression.Constant. That is the one shape EF Core (and most LINQ providers) will not lift into a SQL parameter — it gets inlined as a literal, so Id = '3f2a…' changes with every value. Both the database's plan cache and EF Core's own compiled-query cache are keyed on that text, so neither was doing much work.

What changed

QueryAttribute gained the shared machinery, so custom attributes get it too:

• public bool InlineValue { get; set; } — defaults to false.
• protected Expression BuildValueExpression(queryObject, queryProperty, queryValue, valueType = null) — returns Expression.Property(Expression.Constant(queryObject), queryProperty), the same shape the C# compiler emits for a captured variable. It adds an Expression.Convert only when the declared query-property type is not assignable to the type the call site needs (the Guid? → Guid case the old Expression.Constant(value, targetType) handled). With InlineValue set it falls back to the original constant.

All six value-carrying attributes route through it:

Attribute	valueType requested
SimpleComparisonQueryAttribute (Equals/NotEquals/GreaterThan/…)	targetProperty.PropertyType
StringContainsQueryAttribute, StringStartsWithQueryAttribute	typeof(string)
ContainsQueryAttribute	target collection's element type
AnyOfQueryAttribute (and NoneOfQueryAttribute via inheritance)	IEnumerable<elementType>

NoneOfQueryAttribute needed no edit — it wraps AnyOfQueryAttribute's result in a Not.

Resulting shape:

Param_0 => Param_0.Id == Convert(value(PersonQuery).Id, Guid)
Param_0 => Param_0.Name.Contains(value(PersonQuery).NameContains)
Param_0 => value(PersonQuery).Names.Contains(Param_0.Name)
Param_0 => Param_0.Tags.Intersect(value(PersonQuery).Tags).Any()

EF Core folds each of those evaluatable subtrees, Convert included, into a single parameter, so the SQL text is stable across values and the parameter name comes from the query property (@__Id_0).

Opting out

InlineValue = true on any attribute restores the literal, for cases where inlining is preferable — for example a predicate over badly skewed data where a plan built for the specific value beats reusing one built for a previous value.

[EqualsQuery(InlineValue = true)]
public bool? IsDeleted { get; set; }

Reviewing

Five commits, each building and passing tests on its own:

1. Add InlineValue and BuildValueExpression — mechanism only, no behavior change.
2. Comparison and string attributes.
3. Collection attributes.
4. New tests.
5. Docs.

Commit 2 also converts TestQuery and TestAdvancedQuery from records to plain classes. QueryExpressionBuilderTests asserts exact expression strings, and a record's generated ToString dumps every property value, which the expression printer renders inside the constant node — the assertions would otherwise be long and value-dependent. Nothing relied on their value semantics.

Notes for the release

This is a behavior change for anyone whose provider treats constants and parameters differently. Most will simply see parameterized SQL where they previously saw literals, but a provider that cannot parameterize a given construct would now fail where it previously succeeded; InlineValue = true is the escape hatch.

Two details worth knowing:

• Null semantics are preserved. EF Core's SqlNullabilityProcessor inspects parameter values and emits IS NULL for a null parameter, caching SQL keyed on parameter nullability, so IgnoreIfNull = false with a null value behaves as before.
• Collections improve most on EF Core 8+. There a parameterized collection becomes a single OPENJSON/array parameter. On EF Core 7 and earlier it still expands to IN (@p0, @p1, …), so the SQL shape varies with the element count — better than varying with every value, but not fully stable.

Tests: 34 passing.

🤖 Generated with Claude Code

https://claude.ai/code/session_018pK9kvAcxFsZ3KkYQcEZGP

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