Function findDiscriminator

java/scripts/codegen/java.ts:273–302

* Find a discriminator property shared by all variants in an anyOf. * A discriminator is a property with a `const` value that uniquely identifies each variant.

(variants: JSONSchema7[])

 * A discriminator is a property with a `const` value that uniquely identifies each variant.
 */
function findDiscriminator(variants: JSONSchema7[]): DiscriminatorInfo | null {
    if (variants.length === 0) return null;
    const firstVariant = variants[0];
    if (!firstVariant.properties) return null;

    for (const [propName, propSchema] of Object.entries(firstVariant.properties).sort(([a], [b]) => a.localeCompare(b))) {
        if (typeof propSchema !== "object") continue;
        const schema = propSchema as JSONSchema7;
        if (schema.const === undefined) continue;

        const mapping = new Map<string, { value: unknown; schema: JSONSchema7 }>();
        let isValidDiscriminator = true;

        for (const variant of variants) {
            if (!variant.properties) { isValidDiscriminator = false; break; }
            const variantProp = variant.properties[propName];
            if (typeof variantProp !== "object") { isValidDiscriminator = false; break; }
            const variantSchema = variantProp as JSONSchema7;
            if (variantSchema.const === undefined) { isValidDiscriminator = false; break; }
            const key = String(variantSchema.const);
            if (mapping.has(key)) { isValidDiscriminator = false; break; }
            mapping.set(key, { value: variantSchema.const, schema: variant });
        }

        if (isValidDiscriminator && mapping.size === variants.length) {
            return { property: propName, mapping };
        }
    }
    return null;
}

/**
 * Resolve anyOf variants, handling $ref to definitions.