Can _lodash test an array to check if an array element has a field with a certain value?

Question

I have a variable selectedSubTopicId and I have an array of subTopic objects: objectiveDetail.subTopics[]. Each subTopic object has a field subTopicId

I would like to use this to enable or disable and Add topic button. Can I use lodash in the ng-disabled to test this array and report true if any subTopic object element of the array has a subTopicId that is equal to the selectedSubTopicId.

Here's a sample of the data that's in objectiveDetail. In this case there's just one element in the subTopics array.

{"objectiveDetailId":285,  "objectiveId":29,  "number":1,  "text":"x",  "subTopics":[{"subTopicId":1,                "number":1}] } 

Here is the code in my Angular Controller suggested by thefourtheye:

    $scope.checkDuplicateSubTopicId = function (objectiveDetail, sSubTopic) {         if (_.some(objectiveDetail.subTopics, function(currentTopic) {             return _.contains(currentTopic, selectedSubTopicId);         })) {             return true;         } else {             return false;         }     } 

My button with the click function not shown looks like this:

   <button data-ng-disabled="checkDuplicateSubTopicId(objectiveDetail, subTopicId)">        Add Topic    </button> 

The problem is that it's not quite working and the button does not show disabled.

Answer 1

_{You didn't ask for how to do it, but I assume that's what you wanted to know.}

As I already mentioned, you can use _.some, which will iterate over every element in the array and execute a callback. In that callback you can test whether the value of the topic's property equals the value of the variable:

var result = _.some(objectiveDetail.subTopics, function (topic) {   return topic.subTopicId === selectedSubTopicId; }); 

_.some will skip the remaining elements if it found one for which the callback returned true.