Setting the selected value of a Select element in Handlebars - handlebars.js

Question

I have a handlebars template that I am embedding in my html page. There is a select element with all of the available options already rendered. How can I set the selected value of the select list when I render my template?
<script id="my-template" type="text/x-handlebars-template">
<div id="my-modal">
<form action="/TestAction" method="post">
<input id="MyId" name="MyId" type="hidden" value="{{MyId}}" />
<label for="Test">Test: (optional)</label>
<select id="Test" name="Test">
<option value="">-- Choose Test --</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>
</form>
</div>
</script>

Answer 1

If you don't want to build out the option as part of the helper, you can use a combination of a small custom handlebars helper and parent context, denoted using the ../ syntax:
First write the helper:
Handlebars.registerHelper('selected', function(option, value){
if (option === value) {
return ' selected';
} else {
return ''
}
});
And then in your template you call your helper and pass in the parent context inside the each loop to check for selectedState
{{#each states}}
<option value="{{this}}" {{selected this ../selectedState}}>{{this}}</option>
{{/each}}

Answer 2

I took the {{#each}} helper as inspiration, and wrote a custom helper that does the same thing: loops over a list, and continually appends the contents of the arguments to an output string. (From here: Handlebars block helpers)
In this case, I'm not passing in a chunk of template HTML to serve as the function's options parameter, like you would when using {{#each}}. Instead I am just building up the <option>
tags by brute force, and testing every iteration of the context list. Lastly, I return a big long string of <option></option> tags, and hopefully one of them has selected="selected".
The function:
Handlebars.registerHelper('options_selected', function(context, test) {
var ret = '';
for (var i = 0, len = context.length; i < len; i++) {
var option = '<option value="' + context[i]+'"';
if (test.toLowerCase() == context[i].toLowerCase()) {
option += ' selected="selected"';
}
option += '>'+ Handlebars.Utils.escapeExpression(context[i]) + '</option>';
ret += option;
}
return new Handlebars.SafeString(ret);
});
The tag in use:
<script id="form-state" type="text/x-handlebars-template">
<select name="state">
{{{options_selected states selectedState}}}
</select>
</script>
Please suggest any edits that would improve this, thanks!

Answer 3

You can use values straight in the Handlebars template like so.
Handlebars Template
<select id="distance">
<option value="15" {{#if (isEqual 15 distance)}} selected {{/if}}>15</option>
<option value="25" {{#if (isEqual 25 distance)}} selected {{/if}}>25</option>
<option value="50" {{#if (isEqual 50 distance)}} selected {{/if}}>50</option>
<option value="100" {{#if (isEqual 100 distance)}} selected {{/if}}>100</option>
<option value="300" {{#if (isEqual 300 distance)}} selected {{/if}}>300</option>
</select>
Handlebars Helper
define(['hbs/handlebars'], function (Handlebars) {
'use strict';
Handlebars.registerHelper('isEqual', function (expectedValue, value) {
return value === expectedValue;
});
});

Answer 4

Here is a solution (built over EmberJS to ease the JS part)
I refactored your sample a little, to have objects for proposed values, which can by the way carry the selected attribute...
The template part:
<script type="text/x-handlebars" data-template-name="my-template">
<div id="my-modal">
<form action="/TestAction" method="post">
<input id="MyId" name="MyId" type="hidden" value="{{MyId}}" />
<label for="Test">Test: (optional)</label>
<select id="Test" name="Test">
<option value="">-- Choose Test --</option>
{{#each values}}
<option {{bindAttr value="id" selected="selected"}}>{{label}}</option>
{{/each}}
</select>
</form>
</div>
</script>
The JS part:
App.MyView = Ember.View.extend
templateName: 'my-template'
MyId: 42
values: [{
id: 1,
label: '1'
}, {
id: 2,
label: '2'
}, {
id: 3,
label: '3',
selected: true
}, {
id: 4,
label: '4'
}]
You can try it # http://jsfiddle.net/MikeAski/uRUc3/

Answer 5

I had same problem.
$('select').val(value);
This is how I solved it, I set the desired value with jQuery after rendering the template. Was surprisingly easy. (Maybe its also a way to keep the templates logicless)