index.js

/**!
 * koa-body-parser - index.js
 * Copyright(c) 2014
 * MIT Licensed
 *
 * Authors:
 *   dead_horse <dead_horse@qq.com> (http://deadhorse.me)
 *   fengmk2 <m@fengmk2.com> (http://fengmk2.com)
 */

'use strict';

/**
 * Module dependencies.
 */

var parse = require('co-body');
var copy = require('copy-to');
var forms = require('formidable');

/**
 * @param [Object] opts
 *   - {String} jsonLimit default '1mb'
 *   - {String} formLimit default '56kb'
 *   - {string} encoding default 'utf-8'
 *   - {Object} extendTypes
 */

module.exports = function (opts) {
  opts = opts || {};
  var detectJSON = opts.detectJSON;
  var onerror = opts.onerror;

  var enableTypes = opts.enableTypes || ['json', 'form'];
  var enableForm = checkEnable(enableTypes, 'form');
  var enableJson = checkEnable(enableTypes, 'json');
  var enableText = checkEnable(enableTypes, 'text');
  var enableMultipart = checkEnable(enableTypes, 'multipart');

  opts.detectJSON = undefined;
  opts.onerror = undefined;

  // force co-body return raw body
  opts.returnRawBody = true;

  // default json types
  var jsonTypes = [
    'application/json',
    'application/json-patch+json',
    'application/vnd.api+json',
    'application/csp-report',
  ];

  // default form types
  var formTypes = [
    'application/x-www-form-urlencoded',
  ];

  var multipartTypes = [
    'multipart/form-data'
  ];
  
  // default text types
  var textTypes = [
    'text/plain',
  ];

  var jsonOpts = formatOptions(opts, 'json');
  var formOpts = formatOptions(opts, 'form');
  var textOpts = formatOptions(opts, 'text');
  var multipartOpts = formatOptions(opts, 'multipart');

  var extendTypes = opts.extendTypes || {};

  extendType(jsonTypes, extendTypes.json);
  extendType(formTypes, extendTypes.form);
  extendType(textTypes, extendTypes.text);
  extendType(multipartTypes, extendTypes.multipart);

  return async function bodyParser(ctx, next) {
    if (ctx.request.body !== undefined) return await next();
    if (ctx.disableBodyParser) return await next();
    try {
      const res = await parseBody(ctx);
      ctx.request.body = 'parsed' in res ? res.parsed : {};
      if (ctx.request.rawBody === undefined) ctx.request.rawBody = res.raw;
    } catch (err) {
      if (onerror) {
        onerror(err, ctx);
      } else {
        throw err;
      }
    }
    await next();
  };

  async function parseBody(ctx) {
    if (enableJson && ((detectJSON && detectJSON(ctx)) || ctx.request.is(jsonTypes))) {
      return await parse.json(ctx, jsonOpts);
    }
    if (enableForm && ctx.request.is(formTypes)) {
      return await parse.form(ctx, formOpts);
    }
    if (enableText && ctx.request.is(textTypes)) {
      return await parse.text(ctx, textOpts) || '';
    }
    if (enableMultipart && ctx.request.is(multipartTypes)) {
      return await formable(ctx, multipartOpts);
    }
    return {};
  }
};

function formatOptions(opts, type) {
  var res = {};
  copy(opts).to(res);
  res.limit = opts[type + 'Limit'];
  return res;
}

function extendType(original, extend) {
  if (extend) {
    if (!Array.isArray(extend)) {
      extend = [extend];
    }
    extend.forEach(function (extend) {
      original.push(extend);
    });
  }
}

function checkEnable(types, type) {
  return types.includes(type);
}

function formable(ctx, opts) {
  return new Promise(function (resolve, reject) {
    var fields = {};
    var form = new forms.IncomingForm(opts);
    form.on('end', function () {
      return resolve({
        parsed: fields
      });
    }).on('error', function (err) {
      console.log('reject', err)
      return reject(err);
    }).on('field', function (field, value) {
      if (fields[field]) {
        if (Array.isArray(fields[field])) {
          fields[field].push(value);
        } else {
          fields[field] = [fields[field], value];
        }
      } else {
        fields[field] = value;
      }
    }).on('file', function (field, file) {
      if (fields[field]) {
        if (Array.isArray(fields[field])) {
          fields[field].push(file);
        } else {
          fields[field] = [fields[field], file];
        }
      } else {
        fields[field] = file;
      }
    });
    if (opts.onFileBegin) {
      form.on('fileBegin', opts.onFileBegin);
    }
    form.parse(ctx.req);
  });
}