application.js

import Ember from 'ember';

export default DS.ActiveModelAdapter.extend({

  findQuery: function(store, type, query) {
    // wrap the query in an Ember.Object and pass it through as the "record" to the buildUrl method
    var url = this.buildURL(type.typeKey, null, Ember.Object.create(query));
    return this.ajax(url, 'GET', { data: query });
  },

  // Goal being to have a regex manage this portion and create a declarative style to manage this
  _replaceParts: function (url, id, record) {
    return url;
  },

  pathForType: function (type) {
    return this.get('urlTemplate') || this._super.apply(this, arguments);
  },

  buildURL: function (type, id, record) {
    var url = this._super.apply(this, arguments);
    return this._replaceParts(url, id, record);
  }

});

nested_foo.js

import Ember from 'ember';
import ApplicationAdapter from './application';

export default ApplicationAdapter.extend({
  urlTemplate: 'some/:relatedId/foo',
  
  _replaceParts: function (url, id, record) {
      return url.replace(':relatedId', record.get('relatedId'));
  },
})