Ok, I'm sure there's something simple set wrong here but I'm not 100% what it is.

So I am trying to use Select2 AJAX method as a way of users to search a database and select a result. The call itself is coming back with results, however it will not allow me to select the answer from the list. It also doesn't seem to allow you to "select" it on hover or up/ down arrow. So without further ado, here is my code:

index.html

<html>
    <head>
        <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.0/jquery.min.js"></script>
        <link rel="stylesheet" type="text/css" href="select2/select2.css" media="screen" />
        <script src="select2/select2.js"></script>
        <script src="select.js"></script>
    </head>
    <body>
        <input type="text" style="width: 500px" class="select2">
    </body>
</html>

select.js

jQuery(function() {

  var formatSelection = function(bond) {
    console.log(bond)
    return bond.name
  }

  var formatResult = function(bond) {
    return '<div class="select2-user-result">' + bond.name + '</div>'
  }

  var initSelection = function(elem, cb) {
    console.log(elem)
    return elem
  }

    $('.select2').select2({
      placeholder: "Policy Name",
      minimumInputLength: 3,
      multiple: false,
      quietMillis: 100,
      ajax: {
        url: "http://localhost:3000/search",
        dataType: 'json',
        type: 'POST',
        data: function(term, page) {
          return {
            search: term,
            page: page || 1
          }
        },
        results: function(bond, page) {
          return {results: bond.results, more: (bond.results && bond.results.length == 10 ? true: false)}
        }
      },
      formatResult: formatResult,
      formatSelection: formatSelection,
      initSelection: initSelection
    })
})

JSON Response

{
  error: null,
  results: [
    {
      name: 'Some Name',
      _id: 'Some Id'
    },
    {
      name: 'Some Name',
      _id: 'Some Id'
    }
  ]
}

Everything seems to pull in correctly, however I am unable to actually select the answer and have it input into the box. Is there a problem somewhere in my code?

AlbertEngelB

After looking at another answer it would seem I need to also pass id field with every call, otherwise it will disable the input.

Sample code that fixed it:

$('.select2').select2({
  placeholder: "Policy Name",
  minimumInputLength: 3,
  multiple: false,
  quietMillis: 100,
  id: function(bond){ return bond._id; },
  ajax: {
    url: "http://localhost:3000/search",
    dataType: 'json',
    type: 'POST',
    data: function(term, page) {
      return {
        search: term,
        page: page || 1
      }
    },
    results: function(bond, page) {
      return {results: bond.results, more: (bond.results && bond.results.length == 10 ? true: false)}
    }
  },
  formatResult: formatResult,
  formatSelection: formatSelection,
  initSelection: initSelection
})

Edit

Since this keeps getting upvoted I'll elaborate a bit. The .select2() method expects a unique id field on all results. Thankfully, there's a workaround. The id option accepts a function like this:

function( <INDIVIDUAL_RESULT> ) {
  // Expects you to return a unique identifier.
  // Ideally this should be from the results of the $.ajax() call. 
}

Since my unique identifier was <RESULT>._id, I simply return <RESULT>._id;

The thing is that the JSON data need a property called "id". There's no need for

id: function(bond){ return bond._id; }

If the data does not have an id for itself, you can add it with a function on processResults like here.

        $(YOUR FIELD).select2({
            placeholder: "Start typing...",
            ajax: {
                type: "POST",
                contentType: "application/json; charset=utf-8",
                url: "YOUR API ENDPOINT",
                dataType: 'json',
                data: 
                    function (params) {
                        return JSON.stringify({ username: params.term });
                },
                processResults: function (data, page) {

                    var results = [];

                    $.each(JSON.parse(data.d), function (i, v) {
                        var o = {};
                        o.id = v.key;
                        o.name = v.displayName;
                        o.value = v.key;
                        results.push(o);
                    })

                    return {
                        results: results
                    };
                },
                cache: true
            },
            escapeMarkup: function (markup) { return markup;},
            minimumInputLength: 1,
            templateResult: function (people) {
                if (people.loading)
                    return people.text;

                var markup = '<option value="' + people.value + '">' + people.name + '</option>';

                return markup;
            },
            templateSelection: function (people) { return people.value || people.text }

        });

Also be careful with the case. I was using Id but select2 expects id. Could save someone's time.

Anh Cao

Like Dropped.on.Caprica said: Every result item needs an unique id.

So just assign every result id an unique number:

$('#searchDriver').select2({
    ajax: {
       dataType: 'json',
       delay: 250,
       cache: true,
       url: '/users/search',
       processResults: function (data, params) {
           //data is an array of results
           data.forEach(function (d, i) {
               //Just assign a unique number or your own unique id
               d.id = i; // or e.id = e.userId;
           })

           return {
               results: data
           };
       },
    },
    escapeMarkup: function (markup) { return markup; },
    minimumInputLength: 1,
    templateResult: formatRepo,
    templateSelection: formatRepoSelection
});

I have many problem regarding the following error Option 'ajax' is not allowed for Select2

In my case, appears for select when you are using select2 version 3.5, So you should upgrade to version 4.0 and you won't need hidden input attached to your select

You can trigger selecting an option (in this case the first one) by opening the select2 element programmatically and then triggering a return keypress.

var e = jQuery.Event('keydown');
e.which = 13;

$('.offer_checkout_page_link select').select2('open');
$('.offer_checkout_page_link .select2-selection').trigger(e);

This will "set" the option as if you clicked on it. You can modify this to select a specific option by triggering the appropriate number of down keypresses before triggering the return one.

It seems as though under-the-hood when you click (or in this case hit enter) to select an option, an option element is added to the select element. You will notice that when the page first loads select2 select elements do not have any option element children. This is why other solutions suggest adding an option element using jQuery and then selecting it.

来源：https://stackoverflow.com/questions/14819865/select2-ajax-method-not-selecting

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