app_controllers_membership.js

import Ember from 'ember';

export default Ember.Controller.extend({
  queryParams: ['filter'],

  actions: {
    filterAdded(value) {
      var queryParams = this.get('queryParams');
      queryParams['filter'] = {reference: {contains: value}};
      this.transitionToRoute({ queryParams: queryParams }); 
    }   
  }
});

app_routes_membership.js

import Ember from 'ember';

export default Ember.Route.extend({
  queryParams: {
    'filter': {
      refreshModel: true
    }   
  },  

  model(params) {
    return this.store.query('membership', params);
  }
});