@tsed/schema/lib/esm/domain/JsonDiscriminator.js

JsonSchema module for Ts.ED Framework

import { cleanObject } from "@tsed/core";
/**
 * Manages discriminator mappings for polymorphic type resolution.
 *
 * A discriminator enables polymorphism in schemas by using a specific property
 * value to determine which subtype schema to apply. This is essential for
 * inheritance hierarchies and union types in OpenAPI specifications.
 *
 * ### Concept
 *
 * When a base class has multiple derived classes, the discriminator property
 * (e.g., "type", "kind") indicates which concrete class an object represents.
 *
 * ### Usage
 *
 * ```typescript
 * // Base class
 * @DiscriminatorKey("type")
 * abstract class Animal {
 *   type: string;
 * }
 *
 * // Derived classes
 * @DiscriminatorValue("dog")
 * class Dog extends Animal {
 *   breed: string;
 * }
 *
 * @DiscriminatorValue("cat")
 * class Cat extends Animal {
 *   indoor: boolean;
 * }
 * ```
 *
 * ### OpenAPI Mapping
 *
 * Generates OpenAPI discriminator objects:
 * ```json
 * {
 *   "discriminator": {
 *     "propertyName": "type",
 *     "mapping": {
 *       "dog": "#/components/schemas/Dog",
 *       "cat": "#/components/schemas/Cat"
 *     }
 *   }
 * }
 * ```
 *
 * ### Key Features
 *
 * - **Type Mapping**: Maps discriminator values to TypeScript classes
 * - **Bidirectional Lookup**: Find type by value or values by type
 * - **Default Values**: Get the default discriminator value for a type
 * - **Children Discovery**: List all derived types
 *
 * @public
 */
export class Discriminator {
    constructor({ base, propertyName, types, values } = {}) {
        this.values = new Map();
        this.types = new Map();
        Object.assign(this, cleanObject({
            base,
            propertyName,
            types: types ? new Map(types) : undefined,
            values: values ? new Map(values) : undefined
        }));
    }
    add(type, values) {
        values.forEach((value) => {
            this.values.set(value, type);
        });
        this.types.set(type, values);
        return this;
    }
    getType(discriminatorValue) {
        return this.values.get(discriminatorValue) || this.base;
    }
    getValues(type) {
        return this.types.get(type);
    }
    getDefaultValue(type) {
        const values = this.types.get(type);
        return values ? values[0] : undefined;
    }
    children() {
        return [...new Set([...this.types.keys()])];
    }
}