header（）重定向后如何使用变量？

Question

I've spent ages trying to figure this out after reading guide after guide and I can't get it. I have 3 files - user.php, map.php and newaddress.php. I've only included what I understand to be the important bits to this issue. Happy to provide more info if needed.

user.php passes a "mapnumber" to map.php.

user.php

<form action="map.php" method="post">
   <input type="hidden" name="mapnumber" value="'. $row["mapnumber"].'"/>
   <input type="hidden" name="process" value="process"/>
   <button class="btn btn-primary" type="submit" name="getmap">Process</button>
</form>

map.php receives "mapnumber" and generates a list of addresses from the database with matching "mapnumber". From map.php, user can add new addresses which take the "mapnumber" value and is processed in newaddress.php.

map.php

$mapnumber = $mysqli->escape_string($_POST['mapnumber']);
<form action="newaddress.php" method="post">
<input class="" id="mapnumber" name="mapnumber" value="<?php echo $mapnumber ?>">
<button class="btn btn-primary" id="addaddress" type="submit">Add Address</button>
</form>

newaddress.php adds the address to database with the "mapnumber" value and then redirects back to map.php where it SHOULD generate the list of addresses based on "mapnumber" but map.php doesn't pick up the "mapnumber" from newaddress.php and hence the list of addresses isn't generated.

newaddress.php

$mapnumber = $mysqli->escape_string($_POST['mapnumber']);
header("Location: map.php");
exit;

Please help

Answer 1

You can set the get variable like this:

$mapnumber = $mysqli->escape_string($_POST['mapnumber']); header("Location: map.php?nr=". $mapnumber); exit;

Than in map.php you get get it by: $mapnumber = $mysqli->escape_string($_GET['nr']);

Answer 2

You could use cookies to store values in the remote browser. But the real problem you encounter is that the Location redirect is just that. It tells the browser to load another URL. You can add get requests to that Location redirect URL like that:

header("Location: map.php?mapnumber=".urlencode($mapnumber));

But please keep in mind that the default Location redirect will be a permanent one (HTTP Status Code 301) and it is up to the browser to recheck if the redirecting url/document might have changed or not.

http://php.net/manual/en/function.header.php#78470

So you might want to consider using a 307 redirect:

header("Location: map.php?mapnumber=".urlencode($mapnumber), TRUE,307);

Anyway: passing variables from one page to another is generally not a good practice. Try to avoid it and try to dig into sessions.

http://php.net/manual/en/intro.session.php

Answer 3

I recommend you to use get method in map.php
Then it will receive map number like map.php?mapnumber=somenum

user.php

<form action="map.php" method="get">
   <input type="hidden" name="mapnumber" value="'. $row["mapnumber"].'"/>
   <input type="hidden" name="process" value="process"/>
   <button class="btn btn-primary" type="submit" name="getmap">Process</button>
</form>

map.php

$mapnumber = $mysqli->escape_string($_GET['mapnumber']);
<form action="newaddress.php" method="post">
<input class="" id="mapnumber" name="mapnumber" value="<?php echo $mapnumber ?>">
<button class="btn btn-primary" id="addaddress" type="submit">Add Address</button>
</form>

newaddress.php

$mapnumber = $mysqli->escape_string($_POST['mapnumber']);
header("Location: map.php?mapnumber=$_POST['mapnumber']");
exit;