ethjs-query/lib/index.js

A simple query layer for the Ethereum RPC.

'use strict';

var format = require('ethjs-format');
var EthRPC = require('ethjs-rpc');
var promiseToCallback = require('promise-to-callback');

module.exports = Eth;

function Eth(provider, options) {
  var self = this;
  var optionsObject = options || {};

  if (!(this instanceof Eth)) {
    throw new Error('[ethjs-query] the Eth object requires the "new" flag in order to function normally (i.e. `const eth = new Eth(provider);`).');
  }
  if (typeof provider !== 'object') {
    throw new Error('[ethjs-query] the Eth object requires that the first input \'provider\' must be an object, got \'' + typeof provider + '\' (i.e. \'const eth = new Eth(provider);\')');
  }

  self.options = Object.assign({
    debug: optionsObject.debug || false,
    logger: optionsObject.logger || console,
    jsonSpace: optionsObject.jsonSpace || 0
  });
  self.rpc = new EthRPC(provider);
  self.setProvider = self.rpc.setProvider;
}

Eth.prototype.log = function log(message) {
  var self = this;
  if (self.options.debug) self.options.logger.log('[ethjs-query log] ' + message);
};

Object.keys(format.schema.methods).forEach(function (rpcMethodName) {
  Object.defineProperty(Eth.prototype, rpcMethodName.replace('eth_', ''), {
    enumerable: true,
    value: generateFnFor(rpcMethodName, format.schema.methods[rpcMethodName])
  });
});

function generateFnFor(rpcMethodName, methodObject) {
  return function outputMethod() {
    var callback = null; // eslint-disable-line
    var inputs = null; // eslint-disable-line
    var inputError = null; // eslint-disable-line
    var self = this;
    var args = [].slice.call(arguments); // eslint-disable-line
    var protoMethodName = rpcMethodName.replace('eth_', ''); // eslint-disable-line

    if (args.length > 0 && typeof args[args.length - 1] === 'function') {
      callback = args.pop();
    }

    var promise = performCall.call(this);

    // if callback provided, convert promise to callback
    if (callback) {
      return promiseToCallback(promise)(callback);
    }

    // only return promise if no callback provided
    return promise;

    function performCall() {
      var _this = this;

      return new Promise(function (resolve, reject) {
        // validate arg length
        if (args.length < methodObject[2]) {
          reject(new Error('[ethjs-query] method \'' + protoMethodName + '\' requires at least ' + methodObject[2] + ' input (format type ' + methodObject[0][0] + '), ' + args.length + ' provided. For more information visit: https://github.com/ethereum/wiki/wiki/JSON-RPC#' + rpcMethodName.toLowerCase()));
          return;
        }
        if (args.length > methodObject[0].length) {
          reject(new Error('[ethjs-query] method \'' + protoMethodName + '\' requires at most ' + methodObject[0].length + ' params, ' + args.length + ' provided \'' + JSON.stringify(args, null, self.options.jsonSpace) + '\'. For more information visit: https://github.com/ethereum/wiki/wiki/JSON-RPC#' + rpcMethodName.toLowerCase()));
          return;
        }

        // set default block
        if (methodObject[3] && args.length < methodObject[3]) {
          args.push('latest');
        }

        // format inputs
        _this.log('attempting method formatting for \'' + protoMethodName + '\' with inputs ' + JSON.stringify(args, null, _this.options.jsonSpace));
        try {
          inputs = format.formatInputs(rpcMethodName, args);
          _this.log('method formatting success for \'' + protoMethodName + '\' with formatted result: ' + JSON.stringify(inputs, null, _this.options.jsonSpace));
        } catch (formattingError) {
          reject(new Error('[ethjs-query] while formatting inputs \'' + JSON.stringify(args, null, _this.options.jsonSpace) + '\' for method \'' + protoMethodName + '\' error: ' + formattingError));
          return;
        }

        // perform rpc call
        _this.rpc.sendAsync({ method: rpcMethodName, params: inputs }).then(function (result) {
          // format result
          try {
            _this.log('attempting method formatting for \'' + protoMethodName + '\' with raw outputs: ' + JSON.stringify(result, null, _this.options.jsonSpace));
            var methodOutputs = format.formatOutputs(rpcMethodName, result);
            _this.log('method formatting success for \'' + protoMethodName + '\' formatted result: ' + JSON.stringify(methodOutputs, null, _this.options.jsonSpace));
            resolve(methodOutputs);
            return;
          } catch (outputFormattingError) {
            var outputError = new Error('[ethjs-query] while formatting outputs from RPC \'' + JSON.stringify(result, null, _this.options.jsonSpace) + '\' for method \'' + protoMethodName + '\' ' + outputFormattingError);
            reject(outputError);
            return;
          }
        })['catch'](function (error) {
          var outputError = new Error('[ethjs-query] while formatting outputs from RPC \'' + JSON.stringify(error, null, _this.options.jsonSpace) + '\'');
          reject(outputError);
          return;
        });
      });
    }
  };
}