Question

How can I validate only certain attributes on a model? Currently I check if the attribute exists in the object passed into validate:

validate: function(attrs) {

        // Number
        if (attrs.minimum) {
          if (isNaN(attrs.minimum)) {
            return -1;
          }
        }
        if (attrs.maximum) {
          if (isNaN(attrs.maximum)) {
            return -1;
          }
        }
}

but if I want to validate string value then:

if (attrs.mystring) {
 // Do validation
}

would fail and the validation never takes place.

Answer 1

Im a little confused by your wording, but I think you want to check if its not an empty string first? and also work out the possibility that it is undefined..if so then this is what you’ll want to do..

validate: function(attrs) {
    // Number
    if (attrs.minimum) {
      if (isNaN(attrs.minimum)) {
        return -1;
      }
    }
    if (attrs.maximum) {
      if (isNaN(attrs.maximum)) {
        return -1;
      }
    }
    if (typeof(attrs.mystring) != "undefined"){
      if (!attrs.mystring){
        return -1;
      }
    }
}

if you want to only validate one of your attributes, you should write your validate function to accommodate the options accordingly

validate: function(attrs, option) {
  if (!option){
    // Number
    if (attrs.minimum) {
      if (isNaN(attrs.minimum)) {
        return -1;
      }
    }
    if (attrs.maximum) {
      if (isNaN(attrs.maximum)) {
        return -1;
      }
    }
    if (!attrs.mystring){
      return -1;
    }
  }else{
    switch(option){
      case("string"):
        if (!attrs.mystring){
          return -1;
        }
      break;
      case("number"):
        // Number
        if (attrs.minimum) {
          if (isNaN(attrs.minimum)) {
            return -1;
          }
        }
        if (attrs.maximum) {
          if (isNaN(attrs.maximum)) {
            return -1;
          }
        }
      break;
    }
  }
}

there are many ways to do this, this probably being the least efficient lol but using your example, it will do the job.

also, this isn’t really a backbone.js problem per say…but general js