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polytype

Provider-rendered schemas

Provider hooks replace selected field schemas with json.Marshaler values from functions or methods:

func BoolSchema(_ bool) json.Marshaler {
    return json.RawMessage(`{"type":"boolean"}`)
}


var _ = polytype.Declare(Config.Schema).
    Function(polytype.Field[Config, bool]("Enabled"), BoolSchema).
    RenderProviders()

Available provider chain methods are:

  • .Function(field, fn) for a package function;
  • .Accessor(field, method) for a receiver method taking only the receiver;
  • .Method(field, method) for a receiver method that also accepts the field value;
  • .RenderProviders() to generate RenderedSchema() and execute providers at runtime.

Migration: NewJSONSchemaMethod(Config.Schema, WithFunction(Config{}.Enabled, BoolSchema), WithRenderProviders()) is now Declare(Config.Schema).Function( polytype.Field[Config, bool]("Enabled"), BoolSchema).RenderProviders(). The legacy NewJSONSchemaMethod/NewJSONSchemaFunc with WithFunction, WithStructAccessorMethod, WithStructFunctionMethod, and WithRenderProviders remain supported and source-compatible; each carries a Deprecated: godoc comment naming its fluent equivalent.

Provider implementations must be available in normal builds because RenderedSchema() calls them at runtime. A rendered type does not receive ValidateJSON() because its schema depends on runtime values.

See examples/providers_rendering for all three provider shapes and a runtime test.