but from performance point of view it would be much better to solve it with RewriteRules.
From a performance point of view, it would be far better to resolve this in your application, not .htaccess/mod_rewrite (ie. RewriteRules). You want to always be correctly linking to the canonical URL.
You certainly don't want to be externally redirecting the user as they apply filters in order to "correct" the URL parameter order. The URL parameters should be applied in the "correct" to begin with by your application.
The only time it would be beneficial to "redirect" the user is if they have followed a third party non-canonical link (from another website or search engine) and you need to resolve potential SEO issues. But even then, the code to correct the URL parameter order should be far simpler (and easier to maintain) if implemented as part of your application logic, not .htaccess. The code to do this in .htaccess is comparatively more "complex" (read: messy, potentially harder to maintain, more prone to error, etc.)
However, it is an interesting problem and there might be an occasion when it is preferable (or necessary) to code this in .htaccess (or Apache server config) when you are not able to do this easily in your application.
Solution using mod_rewrite in .htaccess (or server config)
(However, note the comments above - this may not be what you should be doing.)
This is a reasonably generic solution that works in .htaccess (or server config). As it stands, it works on any URL-path. To make it work on a single URL-path (eg. /category/subcategory/, as stated in the question) then modify the pattern in the final RewriteRule directive. For example:
RewriteRule ^category/subcategory/$ %{REQUEST_URI}?%{ENV:NEW_QUERY_STRING} [NE,R=302,L]
Or, you could write an exception at the top to skip these rules for certain URLs if you need to apply it to a group of URLs and not others. This might be more optimal as it avoids any unnecessary processing of the query string.
This block of code would need to go near the top of your .htaccess file. (Order matters.)
This code has the added "benefit" that it also "sanitizes" the query string by removing any URL parameters that are not defined (at the top of the script).
Since it's non-trivial to "simply" determine whether the original URL parameters are already in the correct order, the script goes through the process of constructing a new query string with the URL parameters in the correct order and then compares this to the original query string in order to determine whether a redirect is necessary.
Criteria:
- Up to 10 URL parameters
- Any number of URL parameters can appear in any order
- Empty URL parameters should not be included
- URL parameters are case-sensitive
- Works for any URL-path
- URL parameter names match the regex
[\w-]+ (ie. a-z, A-Z, 0-9, _ and -)
- URL parameter values cannot contain
@ (unless URL encoded)
@@@ cannot appear anywhere in the query string
You simply need to define the URL parameter names at the top of the script, in the order you wish them to be. These are held in environment variables VAR_NAME_01, VAR_NAME_02, etc. The remainder of the script should work unaltered unless:
- you need to add more URL parameters
- OR, change the character used internally to delimit sections in the pattern matching (currently "
@").
- OR, limit the code to a specific URL-path.
Script:
# Define the "name" of each URL parameter
# The numeric order determines the order of the resulting URL parameter list.
# Comment out any URL parameters that are not required.
SetEnvIf ^ ^ VAR_NAME_01=one
SetEnvIf ^ ^ VAR_NAME_02=two
SetEnvIf ^ ^ VAR_NAME_03=three
SetEnvIf ^ ^ VAR_NAME_04=four
SetEnvIf ^ ^ VAR_NAME_05=five
SetEnvIf ^ ^ VAR_NAME_06=six
SetEnvIf ^ ^ VAR_NAME_07=seven
SetEnvIf ^ ^ VAR_NAME_08=eight
SetEnvIf ^ ^ VAR_NAME_09=nine
SetEnvIf ^ ^ VAR_NAME_10=ten
###############################################################################
# Shouldn't need to modify directives below here...
RewriteEngine on
Options +FollowSymLinks
# -----------------------------------------------------------------------------
# Read each URL parameter (if any) and store in corresponding env var
RewriteCond %{QUERY_STRING}@%{ENV:VAR_NAME_01} (?:^|&)([\w-]+)=([^&@]+).*@\1
RewriteRule ^ - [E=VAR_VALUE_01:%2]
RewriteCond %{QUERY_STRING}@%{ENV:VAR_NAME_02} (?:^|&)([\w-]+)=([^&@]+).*@\1
RewriteRule ^ - [E=VAR_VALUE_02:%2]
RewriteCond %{QUERY_STRING}@%{ENV:VAR_NAME_03} (?:^|&)([\w-]+)=([^&@]+).*@\1
RewriteRule ^ - [E=VAR_VALUE_03:%2]
RewriteCond %{QUERY_STRING}@%{ENV:VAR_NAME_04} (?:^|&)([\w-]+)=([^&@]+).*@\1
RewriteRule ^ - [E=VAR_VALUE_04:%2]
RewriteCond %{QUERY_STRING}@%{ENV:VAR_NAME_05} (?:^|&)([\w-]+)=([^&@]+).*@\1
RewriteRule ^ - [E=VAR_VALUE_05:%2]
RewriteCond %{QUERY_STRING}@%{ENV:VAR_NAME_06} (?:^|&)([\w-]+)=([^&@]+).*@\1
RewriteRule ^ - [E=VAR_VALUE_06:%2]
RewriteCond %{QUERY_STRING}@%{ENV:VAR_NAME_07} (?:^|&)([\w-]+)=([^&@]+).*@\1
RewriteRule ^ - [E=VAR_VALUE_07:%2]
RewriteCond %{QUERY_STRING}@%{ENV:VAR_NAME_08} (?:^|&)([\w-]+)=([^&@]+).*@\1
RewriteRule ^ - [E=VAR_VALUE_08:%2]
RewriteCond %{QUERY_STRING}@%{ENV:VAR_NAME_09} (?:^|&)([\w-]+)=([^&@]+).*@\1
RewriteRule ^ - [E=VAR_VALUE_09:%2]
RewriteCond %{QUERY_STRING}@%{ENV:VAR_NAME_10} (?:^|&)([\w-]+)=([^&@]+).*@\1
RewriteRule ^ - [E=VAR_VALUE_10:%2]
# -----------------------------------------------------------------------------
# Construct new query string
# Only with URL parameters that are not empty
RewriteCond %{ENV:VAR_VALUE_01} .
RewriteRule ^ - [E=NEW_QUERY_STRING:%{ENV:VAR_NAME_01}=%{ENV:VAR_VALUE_01}]
RewriteCond %{ENV:VAR_VALUE_02} .
RewriteRule ^ - [E=NEW_QUERY_STRING:%{ENV:NEW_QUERY_STRING}&%{ENV:VAR_NAME_02}=%{ENV:VAR_VALUE_02}]
RewriteCond %{ENV:VAR_VALUE_03} .
RewriteRule ^ - [E=NEW_QUERY_STRING:%{ENV:NEW_QUERY_STRING}&%{ENV:VAR_NAME_03}=%{ENV:VAR_VALUE_03}]
RewriteCond %{ENV:VAR_VALUE_04} .
RewriteRule ^ - [E=NEW_QUERY_STRING:%{ENV:NEW_QUERY_STRING}&%{ENV:VAR_NAME_04}=%{ENV:VAR_VALUE_04}]
RewriteCond %{ENV:VAR_VALUE_05} .
RewriteRule ^ - [E=NEW_QUERY_STRING:%{ENV:NEW_QUERY_STRING}&%{ENV:VAR_NAME_05}=%{ENV:VAR_VALUE_05}]
RewriteCond %{ENV:VAR_VALUE_06} .
RewriteRule ^ - [E=NEW_QUERY_STRING:%{ENV:NEW_QUERY_STRING}&%{ENV:VAR_NAME_06}=%{ENV:VAR_VALUE_06}]
RewriteCond %{ENV:VAR_VALUE_07} .
RewriteRule ^ - [E=NEW_QUERY_STRING:%{ENV:NEW_QUERY_STRING}&%{ENV:VAR_NAME_07}=%{ENV:VAR_VALUE_07}]
RewriteCond %{ENV:VAR_VALUE_08} .
RewriteRule ^ - [E=NEW_QUERY_STRING:%{ENV:NEW_QUERY_STRING}&%{ENV:VAR_NAME_08}=%{ENV:VAR_VALUE_08}]
RewriteCond %{ENV:VAR_VALUE_09} .
RewriteRule ^ - [E=NEW_QUERY_STRING:%{ENV:NEW_QUERY_STRING}&%{ENV:VAR_NAME_09}=%{ENV:VAR_VALUE_09}]
RewriteCond %{ENV:VAR_VALUE_10} .
RewriteRule ^ - [E=NEW_QUERY_STRING:%{ENV:NEW_QUERY_STRING}&%{ENV:VAR_NAME_10}=%{ENV:VAR_VALUE_10}]
# -----------------------------------------------------------------------------
# Trim "&" prefix from the NEW_QUERY_STRING
RewriteCond %{ENV:NEW_QUERY_STRING} ^&(.+)
RewriteRule ^ - [E=NEW_QUERY_STRING:%1]
# Compare with existing QUERY_STRING to determine whether it's in the correct order already
# If different then redirect...
RewriteCond %{QUERY_STRING}@@@%{ENV:NEW_QUERY_STRING} !^(.+)@@@\1
RewriteRule ^ %{REQUEST_URI}?%{ENV:NEW_QUERY_STRING} [NE,R=302,L]
If you have any queries regarding specific parts of this script just say in comments...
