78-Nodejs Course 2023: Resources: Custom Output handlers

// src/app/users/resources/user-resource.ts
import Resource from 'core/resources/resource';
import { uploadsUrl } from 'core/utils/urls';

export default class UserResource extends Resource {
  /**
   * Output shape
   */
  protected output: any = {
    id: 'number',
    name: 'string',
    email: 'string',
    age: 'number',
    avatar: uploadsUrl,
  };
}

// src/core/resources/resource.ts
import { get } from "@mongez/reinforcements";

// this will be used to skip the output property if it is missing from the given resource
const missingKey = Symbol("missing");

export default class Resource {
  /**
   * Constructor
   */
  public constructor(protected resource: any = {}) {
    //
  }

  /**
   * Output shape
   */
  protected output: any = {};

  /**
   * {@inheritDoc}
   */
  public toJSON() {
    // final output
    const data: Record<string, any> = {};

    // loop through the output property
    for (const key in this.output) {
      // get the value type
      const valueType = this.output[key];
      // get the value, and also make sure to skip the output property if it is missing from the given resource
      let value = get(this.resource, key, missingKey);

      // skip the output property if it is missing from the given resource
      if (value === missingKey) {
        continue;
      }

      if (typeof valueType === "string") {
        // cast the value
        value = this.cast(value, valueType);
      } else if (typeof valueType === "function") {
        // call the custom output handler
        value = valueType(value);
      }

      // just for now sett the output value to the data
      data[key] = value;
    }

    return data;
  }

  /**
   * Builtin casts
   */
  protected cast(value: any, type: string) {
    switch (type) {
      case "number":
        return Number(value);
      case "float":
      case "double":
        return parseFloat(value);
      case "int":
      case "integer":
        return parseInt(value);
      case "string":
        return String(value);
      case "boolean":
        return Boolean(value);
      default:
        return value;
    }
  }
}