.htaccess 规则重定向到默认 API 版本

Question

In my PHP API, I would like to redirect requests that don't include a version number to a default version.

So for example, a request to

/api/<endpoint>

will redirect to

/api/v2/<endpoint>

if v2 is the default version for the API. Requests that include a version number should work as normal.

The file structure is like this:

• api
  • v1
  • v2
    • (endpoints)

I'm struggling to understand the .htaccess syntax, and what Apache expression is required. What I've tried so far is to check if the URL contains a version number in it:

RewriteEngine On

# Redirect requests from /api/ to current version of the API
RewriteCond %{DOCUMENT_ROOT} !^(v[0-9])$
RewriteRule ^?$ /v1/$1

Does anyone have experience with this issue or know how to go about solving it?

Answer 1

I'm assuming you mean an internal rewrite, as opposed to an external 3xx "redirect"?

You could do something like the following using mod_rewrite in your root .htaccess file:

# Set env var to default API version
SetEnvIf ^ ^ DEFAULT_API_VERSION=2

# Rewrite requests from /api/ to default version of the API if not explicitly set
RewriteRule ^api/(?!v\d+/)(.*) /api/v${ENV:DEFAULT_API_VERSION}/$1 [L]

The environment variable is just a convenience to avoid having to modify the later rule.

The complete "version" path segment is assumed to be v followed by any number of digits, followed by a slash.

This uses a negative lookahead to avoid matching URLs that already contain a version string as the second path segment. Otherwise the URL-path after /api/ is captured in the $1 backreference and used in the substitution string.

The above will rewrite as follows:

• /api/v1/<endpoint> - no change
• /api/<endpoint> - rewrite to /api/v2/<endpoint>
• /api/ - rewrite to /api/v2/
• /api/v1234/ - no change
• /api/v1234 (no trailing slash) - rewrite to /api/v2/v1234
• /api/v2.1234/foo - rewrite to /api/v2/v2.1234/foo