title: TypeError: Cannot read property 'branchs' of undefined
body: <p>models / branch.js</p>
  
  <pre><code>var mongoose = require('mongoose');
  var Schema = mongoose.Schema;
  var branchSchema = new Schema({
    merchant_id: { type: [String], index: true },
    contact_name: String,
    branch: String,
    phone: String,
    email: String,
    address: String,
    status: String,
    created_date: { type: Date, default: Date.now },
    merchants: [{ type: Schema.Types.ObjectId, ref: 'merchant' }]
  
  });
  var branch = mongoose.model('branch', branchSchema);
  exports = branch;
  </code></pre>
  
  <p>models / merchants.js</p>
  
  <pre><code>var mongoose = require('mongoose');
  var Schema = mongoose.Schema;
  var merchantSchema = new Schema({
    merchant_name: String,
    merchant_type: String,
    contact_name: String,
    phone: String,
    email: String,
    Address: String,
    created_date: { type: Date, default: Date.now },
    branches: [{ type: Schema.Types.ObjectId, ref: 'branch' }]
  });
  var merchant = mongoose.model('merchant', merchantSchema);
  exports = merchant;
  </code></pre>
  
  <p>index.js</p>
  
  <pre><code>var express = require('express');
  var router = express.Router();
  var bodyParser = require('body-parser');
  var mongoose = require('mongoose');
  var merchant = mongoose.model('merchant');
  var branch = mongoose.model('branch');
  
  router.post('/merchants/:merid/branch', function(req, res, next) {
    var branchs = new branch(req.body);
    branch.post = req.post;
    branchs.save(function(err, post) {
      if (err) {
        return next(err);
      }
      req.post.branch.push(merchant);
      req.post.save(function(err, post) {
        if (err) {
          return next(err);
        }
        res.json(branch);
      });
    });
  });
  </code></pre>
  
  <p>I am getting following error:</p>
  
  <blockquote>
    <p>TypeError: Cannot read property 'branchs' of undefined
        at C:\survey-system\routes\index.js:80:14
        at C:\survey-system\node_modules\mongoose\lib\model.js:3431:16
        at C:\survey-system\node_modules\mongoose\lib\services\model\applyHooks.js:144:20
        at _combinedTickCallback (internal/process/next_tick.js:67:7)
        at process._tickCallback (internal/process/next_tick.js:98:9)</p>
  </blockquote>