2009/6/18 PJ <af.gourmet@xxxxxxxxxxxx>:
> Stuart wrote:
>> 2009/6/18 PJ <af.gourmet@xxxxxxxxxxxx>:
>>
>>> I snipped to make it short... continue at bottom...
>>>
>>>> Step back from the code and consider the steps you need to perform...
>>>>
>>>> 1) Get an array of the categories, ideally in the form $cats[<catid>]
>>>> = categoryname.
>>>>
>>>> 2) Get an array of the category IDs that should be selected, i.e.
>>>> $selectedcats = array(3, 5, 7, 9).
>>>>
>>>> 3) Start the HTML select element
>>>>
>>>> 4) foreach ($cats as $id => $catname)
>>>>
>>>> 5) Determine whether it should be selected. e.g. $selected =
>>>> (in_array($id, $selectedcats) ? 'selected="selected"' : ''.
>>>>
>>>> 6) Output the HTML option element, like <option value="$id"
>>>> $selected>$catname</option>, escaping where appropriate.
>>>>
>>>> 7) End of loop, job done.
>>>>
>>>> If your code doesn't have that structure then you may want to consider
>>>> starting again.
>>>>
>>>>
>>> I'm quite sure the structure is correct.
>>>
>>>> Secondly, check that you're not using the same variable name twice.
>>>>
>>> I did find that in an instance of $id being repeated so I changed it to
>>> $bid.
>>>
>>>> In
>>>> one of your previous emails you used $selected to hold the array of
>>>> selected categories, and in another you used it for the text to be
>>>> inserted into the option element. The latter will blat over the former
>>>> leading to no more than 1 option selected, and even then only if it's
>>>> the first option displayed.
>>>>
>>>>
>>> The $selected were not mine... as I was using $ccc ; only started using
>>> $selected a couple of hours ago.
>>>
>>>> If you're still stuck please post more of your code in a single chunk
>>>> including all the elements in my step-by-step above. The snippets
>>>> you're currently posting are not giving us enough context to spot even
>>>> the most common mistakes.
>>>>
>>> I'm including the relevant code:
>>>
>>> // select categories for book to be updated
>>> $sql = "SELECT id, category FROM categories, book_categories
>>> WHERE book_categories.bookID = '$bid' &&
>>> book_categories.categories_id = categories.id";
>>> if ( ( $results = mysql_query($sql, $db) ) ) {
>>> while ( $row = mysql_fetch_assoc($results) ) {
>>> $selected[] = $row['id'];
>>> }
>>> }
>>> else $selected = Array( 0 => '0');
>>> echo $selected;
>>> print_r($selected);
>>>
>>> $sql = "SELECT * FROM categories";
>>> echo "<select name='categoriesIN[]' multiple size='8'>";
>>> if ( ( $results = mysql_query($sql, $db) ) !== false ) {
>>> while ( $row = mysql_fetch_assoc($results) ) {
>>> if (in_array($row['id'], $selected)) {
>>> echo "<option value=", $row['id'], " selected='selected'
>>>
>>>> ", $row['category'], "</option><br />";
>>>>
>>> }
>>> else echo "<option value=", $row['id'], ">",
>>> $row['category'], "</option><br />";
>>> }
>>> }
>>>
>>> Problem #1) in the first query result. I can't figure out how to deal
>>> with it. The code works fine if there are categories assigned to the
>>> book. If not, an undefined variable error is spewed out for selected.
>>>
>>
>> It's best practice to initialise all variables before using them. The
>> code you have will not create the $selected variable if there are no
>> results...
>>
>> (code repeated for clarity)
>>
>>> if ( ( $results = mysql_query($sql, $db) ) ) {
>>>
>>
>> If there are no results this will still "work" so will drop through to...
>>
>>
>>> while ( $row = mysql_fetch_assoc($results) ) {
>>> $selected[] = $row['id'];
>>> }
>>>
>>
>> But since there are no results the first call to mysql_fetch_assoc
>> will return false so the line in the middle will never get executed.
>>
>>
>>> }
>>> else $selected = Array( 0 => '0');
>>>
>>
>> Drop this else line and instead put $selected = array(); before the
>> mysql_query line. Not sure why you want an element 0 => '0' in there,
>> I'm guessing it's one of your attempts to get rid of the notice.
>>
>>
>>> Problem #2) in the second query, the selected is in the source code but
>>> it is not highlited. Several times I did get the categories highlighted,
>>> but I could never catch what it was that made it work.
>>>
>>
>> Can you post the HTML you're getting for this select using the above
>> code. If the selected attributes are in the code correctly then there
>> must be a syntax error in there somewhere and the easiest way to find
>> it will be by looking at the HTML.
>>
>>
> Stuart, you are one clear-headed dude. This is such a nice and clear
> explanation - it's what we need for dummies llike me.
> I had tried to declcare the variable, but didn't understand that it
> needed to be declared as an array; I had put $selected = ""; and
> obviously it din't work.
> As for the seconf problem, today it works. without any changes. I think
> the Quirk Daemon struck my browser. Actuall, I have been sabotaged by
> the cache when, in not thinking and not taking my ridalin, I would
> confuse refresh with go to previous page.
> I guess I can get some sleep now.
> THANKS TO ALL in clearing my brain toward the path of PHP enlightenment.
> :-)
I'd strongly recommend disabling any client-side caching your browser
is doing while developing. On some browsers you can set the cache size
to 0 which will do it. If you can't control it they usually bypass the
cache if you hold control or shift or something else when refreshing.
-Stuart
--
http://stut.net/
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