double-encoded-id

application.controller.js

import Ember from 'ember';
import DS from 'ember-data';
import URLTemplates from '../mixins/url-templates';

export default Ember.Controller.extend({
  id: 'abc xyz',
  
  badUrl: Ember.computed('id', function() {
    return this.defaultAdapter.buildURL('thing', this.get('id'));
  }),
  
  goodUrl: Ember.computed('id', function() {
    return this.customAdapter.buildURL('thing', this.get('id'));
  }),
  
  // Adapter with the default ID segment
  defaultAdapter: DS.RESTAdapter.extend(URLTemplates, {
    urlTemplate: '{pathForType}{/id}'
	}).create(),
  
  // Adapter with the ID segment overridden to just return raw
  customAdapter: DS.RESTAdapter.extend(URLTemplates, {
    urlTemplate: '{pathForType}{/id}',
    
    urlSegments: {
      id: (type, id) => id
    }
	}).create()
});

application.template.hbs

<style>
  body { font-family: sans-serif; }
  td:nth-child(2) { font-family: monospace; }
  table { width: 300px; }
</style>

{{input value=id}}

<table>
	<tr><td>ID</td><td>{{id}}</td></tr>
	<tr><td>Default</td><td>{{badUrl}}</td></tr>
  <tr><td>Correct</td><td>{{goodUrl}}</td></tr>
</table>

mixins.url-templates.js

import Ember from 'ember';

/* global UriTemplate */

var isArray = Ember.isArray;
var sanitize = encodeURIComponent;

var isObject = function(object) { return typeof object === 'object'; };

export default Ember.Mixin.create({
  mergedProperties: ['urlSegments'],
  buildURL: function(type, id, snapshot, requestType, query) {
    var template = this.getTemplate(requestType);

    if (!template) {
      return this._super(...arguments);
    }

    template = this.compileTemplate(template);
    var templateResolver = this.templateResolverFor(type);
    var adapter = this;

    return template.fill(function(name) {
      var result = templateResolver.get(name);

      if (Ember.typeOf(result) === 'function') {
        return result.call(adapter, type, id, snapshot, query);
      } else {
        return result;
      }
    });
  },

  getTemplate: function(requestType) {
    return this.get(requestType + 'UrlTemplate') || this.get('urlTemplate');
  },

  compileTemplate: function(template) {
    return new UriTemplate(template);
  },

  // TODO: Add ability to customize templateResolver
  // TODO: Add reference to the adapter
  templateResolverFor: function(/* type */) {
    return Ember.Object.create(this.get('urlSegments'));
  },

  urlSegments: {
    host: function () { return this.get('host'); },
    namespace: function() { return this.get('namespace'); },
    pathForType: function(type) { return this.pathForType(type); },

    id: function(type, id) {
      if (id && !isArray(id) && !isObject(id)) { return sanitize(id); }
    },

    query: function(type, id, snapshot, query) {
      return query;
    },

    // TODO: Support automatic relationship ids through snapshots api.
    unknownProperty: function(key) {
      return function(type, id, snapshot, query) {
        if (query && query[key]) { return query[key]; }
        if (snapshot) { return snapshot[key]; }
      };
    }
  }
});

twiddle.json

{
  "version": "0.5.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.2.0/ember.debug.js",
    "ember-data": "2.2.0",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.2.0/ember-template-compiler.js",
    "uri-templates": "https://rawgit.com/geraintluff/uri-templates/master/uri-templates.js"
  }
}