I have inside a Backbone model validate function several if statements:

if(!attrs.firstAttr) errorMsg+="first attr mandatory";
if(!attrs.secondAttr) errorMsg+="second attr mandatory";

as you can see there is a lot of repetition (I have actually 10 fields to check with this.

I was thinking of introducing an interface Validator with a method validate. Then implement a MandatoryFieldValidator with:

validate: function(attr, errors) {
   if(!attr) errors.push(attr + " mandatory");

So the validate method would become like this:

mandatoryFieldValidator.validate(attr.firstAttr, errors); // errors now is an array
mandatoryFieldValidator.validate(attr.secondAttr, errors);

Would you think is a good solution? I still don't like it because I need to rewrite it a lot of times. Next step would be to have some kind of foreach but I don't have a list of parameters. The attributes passed by the Backbone validate is an object with the properties of the model.

Would it be ok to declare an array with every element I want to validate like [attr.firstAttr, attr.secondAttr]?

If yes, how would it be possible to do it in Backbone? I'm referring to the fact that _.each function from underscore.js just passes an array with a callback function and I still need to pass the error array and apply the validate method of my Validator.

  • \$\begingroup\$ Have you tried to use Backbone.Validation plugin? It helps a lot! github.com/thedersen/backbone.validation \$\endgroup\$ – Juliano Alves Jul 19 '13 at 14:33
  • \$\begingroup\$ @Juliano I know that plugin but my problem is that part of the validation needs to happen only when certain conditions are met. If I recall correctly, with Backbone.Validation you can't do that. \$\endgroup\$ – dierre Jul 19 '13 at 17:02
  • \$\begingroup\$ I know this is an old post, but in general, providing us the real code with the 10 fields helps us finding a better answer ;) \$\endgroup\$ – konijn Apr 28 '14 at 13:28

I would approach that like this:

Have an array with all the fields you

var mandatoryFields = ['firstAttr','secondAttr'];

Then have a validate function that takes attrs, mandatoryFields and errors

function validate( o , mandatoryFields, errors )
  for( var i = 0 , i < mandatoryFields.length ; i++ )
    var field = mandatoryFields[i];
      errors.push(field + " mandatory");

Note that I replaced attrs with fields but fare more readable, I also added a new-line after that if statement for readability.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.