默认情况下，有条件地选择下拉值

Question

I have a dropdown with 2 options Month & Year . Based on API call response, If period == Y , Year should be selected by default & if period == M , Month should be selected. I dont know how to do this.

<div class="col-sm-3 PDL dateY">
    <select class="form-control" id="sel1" ng-model="SelectedValue_free" ng-options="details.period for details in validity_dd">
    </select>
</div>    

 $scope.validity_dd = [
    {
        period: 'Year'
    }, {
     period: 'Month'
    }
]   

Answer 1

Based on your condition after you get the information from the api, set

 if(period == 'Y') 
 $scope.SelectedValue_free= 'Year';
 else if(period == 'M') 
 $scope.SelectedValue_free= 'Month';

Change you ng-options to ,

 ng-options="details.period as details.period for details in validity_dd"

OR you can set

 if(period == 'Y') 
 $scope.SelectedValue_free= $scope.validity_dd[0];
 else if(period == 'M') 
 $scope.SelectedValue_free= $scope.validity_dd[1];


ng-options="details.period for details in validity_dd"

Answer 2

Use the following script in app.js

$scope.validity_dd = [
    {
        period: 'Year'
    }, {
     period: 'Month'
    }
]   

//this is an array to store all the possible options as key value pairing
$scope.opt_arr={'Y':'Year','M':'Month'};

//Here you can set the value of period with api call response data
$scope.period='M';

//this will search the object from the array which match the data
var result = $.grep($scope.validity_dd, function(e)
            { return e.period == $scope.opt_arr[$scope.period]; });

//this will set the model value so that the required option will be selected
$scope.SelectedValue_free=result[0];