Angular - Checking if a field is empty - angularjs

Question

Bit of a trivial one here however am new to Angular so excuse me.
Whenever I have an input field - I only want an action to occur if the field actually contains some valid content.
What i find I'm having to do is first instantiate a variable, then assign that to whatever input there is then do a boolean check in a if.
Is the the correct way to go around this? If i don't instantiate the variable (or don't use one at all) i run into getting undefined error:
var textToSearch = '';
textToSearch = $scope.main.searchInputField.trim();
if (textToSearch){
$location.path('/search/'+textToSearch);
}
Also (on another note)
I'm sanitising everything on the server side however on Angular/client side is there a quick and easy function I can use?
Thanks

Answer 1

I suppose you have an ng-model for 'main.searchInputField' so if you want to check if the field is empty you can just write
$scope.main = {};
if($scope.main.searchInputField.trim().length > 0){
//do stuff
}

Answer 2

suppose you have ng-model of input field 1 as some.data and input field 2 as some.data1
for(var i=0; i<$scope.some.length;i++){
if($scope.some[i]){
//do something
}
}
it will check every field.

Answer 3

This is using Bootstrap for email validation, but the same logic applies if you are using your own classes.
<div ng-class="(emailRegExp.test(email) && email != null) ? 'has-success' : 'has-error'" class="form-group has-feedback">
<div class="input-group">
<div class="input-group-addon">
<span class="glyphicon glyphicon-envelope"></span>
</div>
<input ng-model="email" ng-change="checkEnableSubmit()" id="email" placeholder="Email Address" type="text" class="form-control" aria-describedby="emailStatus">
</div>
<span ng-class="(emailRegExp.test(email) && email != null) ? 'glyphicon-ok' : 'glyphicon-remove'" class="glyphicon form-control-feedback" aria-hidden="true"></span>
</div>
The ng-class directive accomplishes the validation if:
The checkEnableSubmit() function in your controller only allows a submission when the data is valid (I would be happy to include that code, too)
Both classes in the ternary operator on line #1 indicate valid data and non-valid data (in this example one makes the input appear green and the other red)