在HTML表单中使用多维数组有什么优势？

Question

Regarding the code below: What is the advantage of using the data[Category][county][Macon] array instead of just making the name 'county' or county[], and the value 'Macon', and how would they process the form data on the server side with each checkbox sharing the same value of 1? Also, why does each checkbox have a hidden input with the same name but with a value of 0?

Any assistance with helping this make sense would be appreciated.

<li>
    <div class="input checkbox">
        <input type="hidden" name="data[Category][county][Macon]" id="CategoryCountyMacon_" value="0" />
        <input type="checkbox" name="data[Category][county][Macon]" value="1" id="CategoryCountyMacon" />
        <label for="CategoryCountyMacon">Macon</label>
    </div>
</li>
<li>
    <div class="input checkbox">
        <input type="hidden" name="data[Category][county][Madison]" id="CategoryCountyMadison_" value="0" />
        <input type="checkbox" name="data[Category][county][Madison]" value="1" id="CategoryCountyMadison" />
        <label for="CategoryCountyMadison">Madison</label>
    </div>
</li>

Answer 1

Actually it is quite common in some frameworks. Imagine that Category is the table or a model, county is the column and Madison is the data for the column, or a related data in another lookup table. Looks a little like CakePHP.

Let's say you have a form where a user can update something that has multiple related tables. How do you intelligently and repeatably define what data is bound for what table etc... The framework has logic in the receiving code that looks for the first level keys as the table/model and then the columns and values.

Also, checkboxes are only submitted if they are checked, so if not they won't be in the $_POST array. Defining a hidden input with the same name and value of 0 before the checkbox insures that there will be a value, either 0 if not checked or 1 if checked. It's a way of taking submitted values and using them as opposed to checking if something is present and then doing one thing or the other.

Answer 2

I think you may have over complicated this a bit.

I assume you are showing the user a set of counties and they tick the ones they are interested in.

Now first thing to remember is that a checkbox is only sent back to the script if it is checked, if its not you never see it back in your script. Also what is sent back to the script is the value="something"

So if you are just interested in which counties were selected this is much easier to understand and process back in your script. Also I am not sure what function the hidden fields was serving, I am guessing none.

<li>
    <div class="input checkbox">
        <input type="checkbox" name="counties[]" value="Macon" id="CategoryCountyMacon" />
        <label for="CategoryCountyMacon">Macon</label>
    </div>
</li>
<li>
    <div class="input checkbox">
        <input type="checkbox" name="counties[]" value="Madison" id="CategoryCountyMadison" />
        <label for="CategoryCountyMadison">Madison</label>
    </div>
</li>

So now if Macon and Madison are checked you will get an array called counties returned in the $_POST array like this.

counties[0] = 'Macon'
counties[1] = 'Madison'

So you can process it easily with a

foreach( $_POST['counties'] as $county ) {
    // $county will = 'Macon' on first iteration
    // $county will = 'Madison' on second iteration
}

Of course it may be better still to put the unique key of the counties row from the database into the value attribute ie value="99 rather than the name value="Macon" . That depends upon what you want to do with it later and how you have designed your database.