Master - detail AJAX select boxes

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In this tutorial I will present you how to create a master - detail select box in your forms. Select one item from the master field and the details will be filled accordingly to your selection.

Tutorial info:

Bookmark Master - detail AJAX select boxes

Step 1 - The master - detail concept

Master - detail AJAX select boxes

Time to time you need to create web forms where your visitors can select first a main category and then a subcategory. Think a bit, it is not so easy to implement this solution. Why? You need to fill the first (master) list and the second (detail) list as well. However at design time you don't know which value is selected in the master list so how you should fill the detail page?

Let's see an example:

Main category items:

• Audi
• BMW
• Mercedes
• Lexus

And the subcategories are:

• A3, A4, A6, A8 for Audi
• 320, 520, 630, 745 for BMW
• A180, C200, E320, S500 for Mercedes
• IS200, GS300, LS600 for Lexus

So to fill the master list is quite simple, just add the 4 car brand to the list as here:

Code: 
<select name="brand" id="brand" onchange="doWork();">
  <option value="Audi">Audi</option>
  <option value="BMW">BMW</option>
  <option value="Mercedes">Mercedes</option>
  <option value="Lexus">Lexus</option>
</select>
 
AJAX F1

In case of the detail list we have the problem what items to add. If Audi is the first then the detail select box should look like this:

Code: 
<select name="type" id="type">
  <option value="1">A3</option>
  <option value="2">A4</option>
  <option value="3">A6</option>
  <option value="4">A8</option>
</select>
AJAX F1

But if the visitor made any changes in the master list then our detail list items still the same.

And here comes AJAX to help us. We will send a message to the server when the visitor have changed the value of the master select box. The server will construct a list of relevant detail items and sends back to the browser. Afterwards the browser assigns this list to the detail list.

Now let's see how to implement it.

Tags: ajax select box, ajax master detail, master detail select box