feat(compiler): add CustomScalarCoercer trait for custom scalar validation and coercion#1031
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Abdel-Monaam-Aouini wants to merge 5 commits intoapollographql:mainfrom
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…ation and coercion
duckki
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Apr 13, 2026
| /// Registered custom scalar coercers, keyed by scalar type name. | ||
| /// | ||
| /// Use [`Schema::add_custom_scalar_coercer`] to register a coercer. | ||
| custom_scalar_coercers: HashMap<Name, Arc<dyn CustomScalarCoercer>>, |
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IMO, why don't we allow to set a blanket coercer that handles all customer scalars, instead of adding a map here. So, that the user can decide how to organize this -- either using a map or using a match statement, etc.
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Description:
Adds a CustomScalarCoercer trait that allows users to register custom
validation and coercion logic for custom scalar types. Previously, custom
scalars accepted any value without validation.
The trait provides two extension points:
coerce_variable_value: validates/transforms JSON variable values during input coercion
validate_ast_value: validates AST literal values (e.g., default values) during schema/document validation
Coercers are registered on the Schema via add_custom_scalar_coercer().
When no coercer is registered, the existing permissive behavior is preserved.