Unable to select item in Select2 drop down
I am working on an app that uses Select2 (version 3.5.1). The HTML to setup this drop down / autocomplete field looks like this:
<input id="mySelect" class="form-control" type="hidden">
The form-control class in this snippet comes from Bootstrap. I am initializing this field from JavaScript using the following:
function getItemFormat(item) {
var format = '<div>' + item.ItemName + '</div>';
return format;
}
$(function() {
$('#mySelect').select2({
minimumInputLength: 5,
placeholder: 'Search for an item',
allowClear: true,
ajax: {
url: '/api/getItems',
dataType: 'json',
quietMillis: 250,
data: function (term, page) {
return {
query: term
};
},
results: function (data, page) {
return { results: data, id: 'ItemId', text: 'ItemText' };
}
},
formatResult: getItemFormat,
dropdownCssClass: "bigdrop",
escapeMarkup: function (m) { return m; }
});
});
When my select field loads, it successfully renders. Once I type at least the fifth character, it successfully pulls items from the server and lists them as options. However, if I try to select one of them, nothing happens. The drop-down popup stays open. Nothing gets put in the actual field. There are no errors in the JavaScript console. Its like I didn't click anything.
In addition, I noticed that nothing is highlighted when I put my mouse over an item or attempt to navigate the list of options with the arrow keys.
What am I doing wrong?
Answer
What is happening:
By default, results of the object you are returning in ajax.results should be an array in this structure [{id:1,text:"a"},{id:2,text:"b"}, ...].
results: function (data, page) {
var array = data.results; //depends on your JSON
return { results: array };
}
In Select2.js it actually states:
* @param options.results a function(remoteData, pageNumber, query) that converts data returned form the remote request to the format expected by Select2.
* The expected format is an object containing the following keys:
* results array of objects that will be used as choices
* more (optional) boolean indicating whether there are more results available
* Example: {results:[{id:1, text:'Red'},{id:2, text:'Blue'}], more:true}
Reading the source code, we can see that ajax.results is called on AJAX success:
success: function (data) {
// TODO - replace query.page with query so users have access to term, page, etc.
// added query as third paramter to keep backwards compatibility
var results = options.results(data, query.page, query);
query.callback(results);
}
So ajax.results is really just a function for you to format your data into the appropriate structure ( e.g. [{id:a,text:"a"},{id:b,text:"b"}, ...]) before the data is passed to query.callback:
callback: this.bind(function (data) {
// ignore a response if the select2 has been closed before it was received
if (!self.opened()) return;
self.opts.populateResults.call(this, results, data.results, {term: term, page: page, context:context});
self.postprocessResults(data, false, false);
if (data.more===true) {
more.detach().appendTo(results).html(self.opts.escapeMarkup(evaluate(self.opts.formatLoadMore, self.opts.element, page+1)));
window.setTimeout(function() { self.loadMoreIfNeeded(); }, 10);
} else {
more.remove();
}
self.positionDropdown();
self.resultsPage = page;
self.context = data.context;
this.opts.element.trigger({ type: "select2-loaded", items: data });
})});
And what query.callback eventually does is to set the logic up properly so that everything works fine when you choose one of the items and trigger .selectChoice.
selectChoice: function (choice) {
var selected = this.container.find(".select2-search-choice-focus");
if (selected.length && choice && choice[0] == selected[0]) {
} else {
if (selected.length) {
this.opts.element.trigger("choice-deselected", selected);
}
selected.removeClass("select2-search-choice-focus");
if (choice && choice.length) {
this.close();
choice.addClass("select2-search-choice-focus");
this.opts.element.trigger("choice-selected", choice);
}
}
}
So if there is some misconfiguration (e.g. results is not in the correct structure) that causes the class .select2-search-choice-focus not to be added to the DOM element before .selectChoice is called, this is what happens:
The drop-down popup stays open. Nothing gets put in the actual field. There are no errors in the JavaScript console. Its like I didn't click anything.
Solutions
There are many solutions to this. One of them is, of course, do some array keys manipulation in ajax.results.
results: function (data, page) {
//data = { results:[{ItemId:1,ItemText:"a"},{ItemId:2,ItemText:"b"}] };
var array = data.results;
var i = 0;
while(i < array.length){
array[i]["id"] = array[i]['ItemId'];
array[i]["text"] = array[i]['ItemText'];
delete array[i]["ItemId"];
delete array[i]["ItemText"];
i++;
}
return { results: array };
}
But you may ask: why must the id be "id" and the text be "text" in the array?
[{id:1,text:"a"},{id:2,text:"b"}]
Can the array be in this structure instead?
[{ItemId:1,ItemText:"a"},{ItemId:2,ItemText:"b"}]
The answer is yes. You just need to overwrite the id and text functions with your own functions.
Here are the original functions for .selecte2 in Select2.js:
id: function (e) { return e == undefined ? null : e.id; },
text: function (e) {
if (e && this.data && this.data.text) {
if ($.isFunction(this.data.text)) {
return this.data.text(e);
} else {
return e[this.data.text];
}
} else {
return e.text;
}
},
To overwrite them, just add your own functions inside the object you are passing to .selecte2:
$('#mySelect').select2({
id: function (item) { return item.ItemId },
text: function (item) { return item.ItemText }
......
});
Updates
What else is happening :
However, the text of the selected item does not appear in the field after the list closes.
This means .selectChoice has been successfully executed. Now the problem lies in .updateSelection. In the source code:
updateSelection: function (data) {
var container=this.selection.find(".select2-chosen"), formatted, cssClass;
this.selection.data("select2-data", data);
container.empty();
if (data !== null) {
formatted=this.opts.formatSelection(data, container, this.opts.escapeMarkup);
}
if (formatted !== undefined) {
container.append(formatted);
}
cssClass=this.opts.formatSelectionCssClass(data, container);
if (cssClass !== undefined) {
container.addClass(cssClass);
}
this.selection.removeClass("select2-default");
if (this.opts.allowClear && this.getPlaceholder() !== undefined) {
this.container.addClass("select2-allowclear");
}
}
From here we can see that, before the corresponding string of text is placed into the input, it would call formatSelection.
formatSelection: function (data, container, escapeMarkup) {
return data ? escapeMarkup(this.text(data)) : undefined;
},
Update: Solution
Previously I thought this.text(data) can be overwritten by having text: funcion(item){ ... } in the parameters, but sadly it doesn't work that way.
Therefore to render the text properly in the field, you should overwrite formatSelection by doing
$('#mySelect').select2({
id: function (item) { return item.ItemId },
formatSelection: function (item) { return item.ItemText }
//......
});
instead of trying to overwrite text (which should supposedly have the same effect but this way of overwriting is not yet supported/implemented in the library)
$('#mySelect').select2({
id: function (item) { return item.ItemId },
text: function (item) { return item.ItemText } //this will not work.
//......
});