Link 2 observable arrays together with knockout js

2
votes

I have 2 arrays. One is an array of all schools in an area, the other is a list of all students at those schools. The student objects contain know which school they belong to. I can make a list of all the schools and I can make a list of all the students. I'd like to be able to select a school (or a couple schools) and have the list of students only show students from that school.

Here's what I've got (in CoffeeScript):

ViewModel = () ->
    @accounts = ko.observableArray([])
    @players_to_teams = ko.observableArray([])
    @selected_players_to_teams = ko.observableArray([])
    @selected_schools = ko.observableArray([])
    null

View:

<label for="school_selection">School</label>
<select id="school_selection" class="inline" multiple=true size="50" data-bind="options:accounts, optionsText: 'Name', selectedOptions: selected_schools"></select>


<div id="player_list" class="inline">
  <table class="table table-striped">
    <thead>
    <tr>
      <th id="firstName">First Name</th>
      <th id="lastName">Last Name</th>
      <th id="position">Position</th>
      <th id="teamName">Team Name</th>
      <th id="accountId">Account ID</th>
    </tr>
    </thead>
    <tbody data-bind="foreach: selected_players_to_teams">
    <tr>
      <td data-bind="text: FirstName"></td>
      <td data-bind="text: LastName"></td>
    </tr>
    </tbody>
  </table>
</div>

When selected_schools changes, I need to update selected_players_to_teams to only contain the student records that have schools in the selected_schools array?

Is there a way to link observableArrays, make observableArrays a function, or maybe catch a call back for an observableArray?

1
knockout.js

1 Answers

2
votes

I suggest implementing selected_players_to_teams as a ko.computed that runs when selected_schools is updated, and returns the players_to_teams for the selected_schools.

See this jsfiddle for a code-only example: http://jsfiddle.net/MqNPm/

Tuan