How to get this.userId in function inside Meteor method

问题

I need to call a few times a function for every user who is logged in, but when the function is placed inside meteor method, this.userId becomes undefined inside function scope, here's the example:

myMethod: function(){

  console.log(this.userId); // this returns proper userId

  function innerFunction(){
    console.log(this.userId); // this returns undefined
  };
  innerFunction();

}

How can I pass this.userId inside a function? Does a function has to be binded with Meteor.bindEnvironment?

回答1:

You have some variants to resolve this:

use .bind() method:

myMethod: function () {
 console.log(this.userId); // this returns proper userId

 function innerFunction() {
     console.log(this.userId); // this returns undefined
 }

 innerFunction.bind(this);
}

use .apply() method for applying correctthis into function:

myMethod: function () {
 console.log(this.userId); // this returns proper userId

 function innerFunction() {
     console.log(this.userId); // this returns undefined
 };

 innerFunction.apply(this);
}

also you can just use that insted of thisfor pass the scope into in innerFunction:

myMethod: function () {
    var that = this;
    console.log(this.userId); // this returns proper userId

    function innerFunction() {
       console.log(that.userId); // this returns undefined
    }

    innerFunction();
}

or just pass userId into innerFunction

myMethod: function () {
  var userId = this.userId;
  console.log(this.userId); // this returns proper userId

  function innerFunction(userId) {
      console.log(userId); // this returns undefined
  }

  innerFunction();
}

回答2:

There are a couple of ways you can do it:

myMethod: function () {
    var me = this;

    function innerFunction () {
        console.log(me.userId);
    };

    innerFunction();
}

myMethod: function () {
    var innerFunction = function () {
        console.log(this.userId);
    }.bind(this);

    innerFunction();
}

回答3:

have you tried to bind the function ?

   myMethod: function(){

      console.log(this.userId); // this returns proper userId


  function innerFunction(){
    console.log(this.userId); // this returns undefined
  }.bind(this);
  innerFunction();

}

来源：https://stackoverflow.com/questions/30576136/how-to-get-this-userid-in-function-inside-meteor-method

标签

javascript

methods

meteor