[RESOLVED] Newbie question: passing search params

maddaze

Hi all,

While an experienced developer of workgroup-oriented, database-based applications, I'm struggling with my first Web-based application, and I'm have several questions that I suspect are easy to answer for an experienced PHP developer. I'll post the questions separately to make them easier to answer.

By way of introduction I live in Bordeaux, France and am developing a Web site to display photos I've taken of the churches in the area. (There are at least a thousand, and some are nearly a thousand years old.) I'm using PHP5 (PHPEdit) and MySQL5.

Here's the first question:

Background:
At the heart of the site is a home page which is essentially a search page. On it a user can, for example, 1) enter the name of a town whose church(es) he wants to see and then click on a Submit button or 2) click on a letter in a list of the letters that town names begin with. In either case I want to go to a display page that all searches will send the user to. I need to pass to the display page what the user entered/clicked on the home page, so that the display page can decide what to display, for example, 1) a list of churches in a town if there's more than one, 2) a list of towns that begin with the specified letter, or 3) photos of a church if there's only one church in the specified town.

Question:
When a user clicks on the letter A in the list of letters, how do I inform the display page that the user clicked on A? At the moment I've highlighted the letter A on the home page using <a href='displaypage.php'>A</a>. Rather than use cookies, I'm trying to put the search parameters after the URL, but can't figure out an easy way to do it using <a>. Suggestions? Better idea?

Harvey

etully

Harvey, What you're asking isn't difficult.

The key thing to remember here is that you are performing two different kinds of searches.  Therefore, your Search Results page will also need to determine which type of search the user wants to perform.

One way to do that is to pass an additional variable that indicates the search type.  The other way to do it is to pass one variable (for example, $town_letter) for one kind of search and a different variable ($town_name) for the other kind of search.  If you choose the 2nd method,  then you will check to see if $town_letter has a value.  If so, then execute the code that searches for towns that start with that letter.  If $town_letter has no value and $town_name does, then you perform the other kind of search showing all the churches in that town.

I prefer to do this with two variables because invariably, your client will complicate the user interface and there could (hypothetically) be situations where both $town_letter and $town_name have values and your code won't know which search to perform.

To answer your question about syntax, here's how you put variables in a URL.  Change your <a href> tag to this:

When someone clicks the letter "A",  the following page (displaypage.php) can determine which letter was clicked like this:

$town_letter = $_REQUEST['town_letter'] ;

Similarly, you will want to access the other variables:

$search_type = $REQUEST['search_type'] ;
$town_name = $REQUEST['town_name'] ;

Now you will have received all the data from the previous page and you can begin your logic like this:

Connect to the database
Display Page Header
if ($search_type==1) {
$query = "select distinct town_name from church_data where town like '$town_letter%'";
Display Results
}
if ($search_type==2) {
$query = "select church_photo_filename from church_data where town='$town_name'";
Display Results
}
Display Footer

Note that the example above passes the variable by attaching it to a URL. Another technique for passing information to displaypage.php could be this:

<form action="displaypage.php" method="post">
Choose your town: <select name=town_name>
<option value="Paris">Paris
<option value="Lille">Lille
<option value="Marque En Borough">Marque En Borough
</select>
<input type="submit" value="Show Churches in this town">
<input type="hidden" name="search_type" value="2">
</form>

maddaze

etully,

First, a hearty thanks for a lovely response. And my apologies for taking so long to respond. Between house guests and playing with session variables, I've been distracted.

[ The key thing to remember here is that you are performing two different kinds of searches. Therefore, your Search Results page will also need to determine which type of search the user wants to perform.]

I'm well aware of that, and in fact the Search Results will actually have to deal with other types of searches I didn't talk about.

[ One way to do that is to pass an additional variable that indicates the search type. The other way to do it is to pass one variable (for example, $town_letter) for one kind of search and a different variable ($town_name) for the other kind of search. If you choose the 2nd method, then you will check to see if $town_letter has a value. If so, then execute the code that searches for towns that start with that letter. If $town_letter has no value and $town_name does, then you perform the other kind of search showing all the churches in that town.]

My thought is constuct a string passed in the URI that contains different codes that communicate the type of search of search and the search parameter(s). For example,
/display.php?en|hm|tn=Arcins
or
/display.php?fr|hm|tl=A

The string after the ? gives 1) the language chosen by a visitor, 2) the 2nd page visited (necessarily the home page), 3) the type of search selected then, where tn is Town Name and tl is Town Letter.

[I prefer to do this with two variables because invariably, your client will complicate the user interface and there could (hypothetically) be situations where both $town_letter and $town_name have values and your code won't know which search to perform.]

Since I am the client, I have absolute control.

[ To answer your question about syntax, here's how you put variables in a URL. Change your <a href> tag to this:

<a href='displaypage.php?town_letter=A&search_type=1'>A</a>]

I see you separated the params in the string after the ? by &s. Is that a convention, necessary, or ??? As you see in my example above, I'd thought to use |s, then use $_SERVER['REQUEST_URI'] to retrieve the URI, so I could parse out what I wanted.

[[When someone clicks the letter "A", the following page (displaypage.php) can determine which letter was clicked like this:

$town_letter = $_REQUEST['town_letter'] ;

Similarly, you will want to access the other variables:

$search_type = $REQUEST['search_type'] ;
$town_name = $REQUEST['town_name'] ;]

I see you're using $_REQUEST to get the parameters from the URI. I can't seem to find any documentation on doing that. Where I would look to find more on this? It's easier than what I've started to implement.

[<form action="displaypage.php" method="post">
Choose your town: <select name=town_name>
<option value="Paris">Paris
<option value="Lille">Lille
<option value="Marque En Borough">Marque En Borough
</select>
<input type="submit" value="Show Churches in this town">
<input type="hidden" name="search_type" value="2">
</form>[/QUOTE]]

I'll be doing some of that, although given the fact that there are over 500 towns and over 1000 churches, it's not practical to display complete lists (unless the user asks for them). So on the basic search page (the Home Page), the user can type in the name of a town or church he's interested in if he knows it.

And I see you've answered a question I haven't yet asked, namely, how to hide data on a page, i.e., input type=hidden. That lets me hide a parameter indicating the language chosen by the user.

Thanks again for a clear and cogent response.

Harvey

Houdini

Actually $REQUEST is a predefined variable that contains values of $POST, $GET, and $COOKIE. You could have used $GET to achieve the same result. All variables passed through the URL are $GET variables, and also $REQUEST variables (See the PHP Manual here on predefined variables)Values are passed through the URL with key value pairsafter the ? sign, and each additional key value pair must be seperated with an ampersand (&) so ?text=yes&action=new would pass two key value pairs in the URL the first key either $GET['text'] or $REQUEST['text'] would have a value of yes and the second key either $GET['action'] or $_REQUEST['action'] would have a value of new

maddaze

That's kinda cool. Thanks for the clarification.

Harvey

PS: I observe in passing that, having read the the PHP manual on $GET and $REQUEST, I don't see anything there that suggests one can find values from the URI in those arrays. (I often have the sense that if I were working in a PHP shop rather than alone, I'd be making a HELL of a lot more progress on this Web site. [sigh])

Houdini

Then you could learn more from the SUPERGLOBALS section of the Practical PHP Programming at this link. Once on that page you might want to go to the Table of Contents at the bottom of the page and centered.

maddaze

Excellent advice! Have bookmarked the site.

Harvey