Question

26

How do you iterate over Mongoose model properties within a middleware function?

rated 0 times [ 28] [ 2] / answers: 1 / hits: 6110 / 10 Years ago, mon, june 30, 2014, 12:00:00

I'm attempting to iterate over fields in a mongoose model within a middleware function. The current context this is the model object itself. So I have a function in which the context is a Javascript object like this:

{

  lastName: 'Wilkens',

  firstName: 'Elepart',

  name: 'Elepart Wilkens',

  username: 'eK',

  bio: '<script>alert('this is a hack!!')',

  _id: 53b17dd0e8c5af50c1d73bc6,

  language: 'en',

  country: 'USA',

  online: true

}

I want to iterate over this object (which is represented in the current function with this). Every time I attempt to iterate with loops, it prints out values that look like internal Javascript metadata. Is it possible to iterate over this within a function if this represents an object?

Here's the actual middleware function:

userSchema.pre('save', function (next) {

    console.log(this); // This prints precisely the same object I have copied above



    var fields = Object.keys(this);



    for(var i = 0; i < fields.length; i++) {

        console.log(this[fields[i]]);

    }



    for(var key in this) {

      if(this.hasOwnProperty(key)) {

        console.log(this[key]);

      }

    }

});

And the output is:

{ 

 strictMode: true,

 selected: undefined,

 shardval: undefined,

 saveError: undefined,

 validationError: undefined,

 adhocPaths: undefined,

 removing: undefined,

 inserting: undefined,

 version: undefined,

 getters: {},

 _id: undefined,

 populate: undefined,

 populated: undefined,

 wasPopulated: false,

 scope: undefined,

 activePaths: 

   { paths: 

      { username: 'modify',

        firstName: 'modify',

        name: 'modify',

        online: 'default',

        country: 'default',

        language: 'default',

        _id: 'default',

        bio: 'modify',

        lastName: 'modify' },

     states: { default: [Object], init: {}, modify: [Object], require: {} },

     stateNames: [ 'require', 'modify', 'init', 'default' ],

     map: [Function] },

  ownerDocument: undefined,

  fullPath: undefined }

true

undefined

0

{ online: true,

  country: 'USA',

  language: 'en',

  _id: 53b1825a00ed9af7c12eedf9,

  bio: '<script>alert('this is a hack!!')',

  username: 'yK',

  name: 'Yershay Wilkens',

  firstName: 'Yershay',

  lastName: 'Wilkens' }

{ save: 

   [ { [Function] isAsync: false },

     { [Function: checkForExistingErrors] isAsync: false },

     { [Function: validation] isAsync: false },

     { [Function] isAsync: false },

     { [Function] isAsync: false } ],

  validate: [ { [Function] isAsync: false } ] }

{ save: [], validate: [] }

{ [Function] numAsyncPres: 0 }

{ [Function] numAsyncPres: 0 }

{}

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kylee

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1 Year ago

answered 10 Years ago dequant · Accepted Answer

I found a slightly different way to accomplish what I wanted which was to iterate over the model properties of a Mongoose model within a middleware function. This uses async.js, but you could refactor it to use a generic JS loop or any other control flow library. The key is to get an array of the document's fields, then you can iterate over those and get/set the values using the current context with this. As far as I know, this will not coerce non-string values into strings. I've tested it with strings, numbers, booleans and objectIds and they are successfully saved as their original data types.

yourSchema.pre('save', function (next) {

  var self = this;



  // Get the document's fields

  var fields = Object.keys(this._doc);



  // Do whatever you want for each field

  async.each(fields, function(field, cb) {

    self[field] = validator.escape(self[field]);

    cb();

  }, function(err){

    next();

  });

});