jayson/lib/generateRequest.js

'use strict';

const isString = require('lodash/isString');
const isUndefined = require('lodash/isUndefined');
const isObject = require('lodash/isObject');
const isArray = require('lodash/isArray');
const isFunction = require('lodash/isFunction');
const uuid = require('uuid/v4');

/**
 *  Generates a JSON-RPC 1.0 or 2.0 request
 *  @param {String} method Name of method to call
 *  @param {Array|Object} params Array of parameters passed to the method as specified, or an object of parameter names and corresponding value
 *  @param {String|Number|null} [id] Request ID can be a string, number, null for explicit notification or left out for automatic generation
 *  @param {Object} [options]
 *  @param {Number} [options.version=2] JSON-RPC version to use (1 or 2)
 *  @param {Function} [options.generator] Passed the request, and the options object and is expected to return a request ID
 *  @throws {TypeError} If any of the parameters are invalid
 *  @return {Object} A JSON-RPC 1.0 or 2.0 request
 *  @memberOf Utils
 */
const generateRequest = function(method, params, id, options) {
  if(!isString(method)) {
    throw new TypeError(method + ' must be a string');
  }

  options = options || {};

  const request = {
    method: method
  };

  // assume that we are doing a 2.0 request unless specified differently
  if(isUndefined(options.version) || options.version !== 1) {
    request.jsonrpc = '2.0';
  }

  if(params) {

    // params given, but invalid?
    if(!isObject(params) && !isArray(params)) {
      throw new TypeError(params + ' must be an object, array or omitted');
    }

    request.params = params;

  }

  // if id was left out, generate one (null means explicit notification)
  if(typeof(id) === 'undefined') {
    const generator = isFunction(options.generator) ? options.generator : function() { return uuid(); };
    request.id = generator(request, options);
  } else {
    request.id = id;
  }

  return request;
};

module.exports = generateRequest;