Form Validation with Dependent Fields in AngularJS

问题

I have an object that has 2 fields, while 1 should be less than or equal to another.

Say it's HDD quota settings and I need the threshold to be less than or equal to HDD's size.

I am trying to use angular's ui-utils#validate.

This is how I got so far: http://embed.plnkr.co/EysaRdu2vuuyXAXJcJmE/preview (i hope the link will work)

The problem that I am having is that it works to one direction:

Setting size and then playing with threshold works ok

But if I try to change size, after threshold is in invalid state - nothing happens. This is because invalid threshold is not set on the model and size id being compared against null or undefined (or something like that).

On one hand I understand the logic of not setting invalid value on the model... but here it is getting in my way.

So, any help making this work will be appreciated.

回答1:

I have played with custom directives and cooked something that works for my case.

On my input for threshold I have less-than-or-equal="quota.size" directive, passing it the model's property to validate against (I want quota.threshold to be less than or equal to quota.size):

<input type="number" name="threshold" 
    ng-model="quota.threshold" 
    required 
    less-than-or-equal="quota.size" />

In link function of lessThanOrEqual directive it starts to watch the quota.size and when quota.size changes it just tries to set the current view value of threshold on model:

link: (scope, elem, attr, ctrl) ->
    scope.$watch attr.lessThanOrEqual, (newValue) ->
        ctrl.$setViewValue(ctrl.$viewValue)

Then there is the parser that does the validation by calling scope.thresholdValidate(thresholdValue) method passing it the candidate value. This method returns true if validation succeeded and if it does - it returns the new value, otherwise - current model's value:

    ctrl.$parsers.push (viewValue) ->
        newValue = ctrl.$modelValue
        if not scope.thresholdValidate viewValue    
            ctrl.$setValidity('lessThanOrEqual', false)
        else
            ctrl.$setValidity('lessThanOrEqual', true)
            newValue = viewValue
        newValue

I am pushing the parser to parser collection, as opposite to unshifting it like most of the examples suggest, because I want angular to validate required and number directives, so I get here only if I have a valid and parsed number (less work for me, but for text inputs I probably should do the parsing job)

Here is my playground: http://embed.plnkr.co/EysaRdu2vuuyXAXJcJmE/preview

回答2:

Better late than never, you need to add ng-model-options="{allowInvalid:true}" to your form input elements to stop this happening - the problem is that when a promise is rejected (e.g. using $q or $http) the model, by default, is not updated. Crazy huh! Cost me a day working this out.

I have written a plunkr specifically for this problem - Trust me this code is good ... http://embed.plnkr.co/xICScojgmcMkghMaYSsJ/preview

来源：https://stackoverflow.com/questions/16798388/form-validation-with-dependent-fields-in-angularjs