url_prefix is repeated in the url

[Davidiam]

Py4web: 1.20250607.2 on Python 3.13.5

nginx reverse proxy configuration

The url_prefix is repeated in the url in the following scenario:

• I open the _dashboard app
• I click on the _scaffold app
• I go to the Databases in _scaffold
• I click on auth_user
• I click on the New button
• It doubles my url_prefix in the url and gives a 404

Work-around: add a rewrite in my nginx config file to remove one of the 2 prefixes (the url is still incorrect in the hover)

Looking for solution in py4web:

I suspect that it has something to do with an absolute path somewhere instead of a relative path.  Maybe it is in dbabmin.js but I can't access this in my browser debugger for some reason.  

This is what I see when I hover over the New button (server and referrer modified) :

https://server.example.com:XXXX/myurlprefix/myurlprefix/_dashboard/dbadmin/_scaffold/db/auth_user?mode=new&referrer=68747499999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999

Any ideas as to where or how to debug this appreciated.

[Davidiam]

Ok, I am beginning to see what is occuring.  The problem seems to come from the grid object when using a reverse proxy:

For some reason the grid object is causing duplicate url_prefixes : Any idea how to fix this? 

In _dashboard layout.html

  <!-- beginning of HTML inserted by extending templatey -->

    <center>

      <div>

        <!-- Flash alert messages, first optional one in data-alert -->

        <flash-alerts class="padded" data-alert="[[=globals().get('flash','')]]"></flash-alerts>

      </div>

      <main class="padded">

        <!-- contect injected by extending page layout.html in dashboard -->

        [[include]]

      </main>

    </center>

    <!-- end of HTML inserted by extending template -->

 

dbadmin.html:

[[extend "layout.html"]]

<h2>Table "[[=table_name]]"</h2>

[[=grid]]  ===========================> This seems to be triggering the double prefixes

 

<a class="grid-new-button info" href="/myfirsteuda/p/myfirsteuda/p/_dashboard/dbadmin/_scaffold/db/auth_user?mode=new&amp;referrer=687474703A2F2F733273303065676B2E62652E7372762E6465762E7379733A383434332F6D796669727374657564612F702F5F64617368626F6172642F646261646D696E2F5F73636166666F6C642F64622F617574685F75736572" role="button"><i class="fas fa-plus"></i><span class="grid-new-button-text">&nbsp;New</span></a>

[Davidiam]

BUG Found:

The problem occurs in URL line 901 - 906:

In this case, the url_prefix = /myfirsteuda/p

and prefix = /myfirsteuda/p/_dashboard/dbadmin/

So once the url is created, it has a double prefix!! : /myfirsteuda/p/myfirsteuda/p/_dashboard/dbadmin/

url_prefix = os.environ.get("PY4WEB_URL_PREFIX", "")

    url = (

        url_prefix

        + prefix

        + "/".join(urllib.parse.quote(part, safe=r":/{}") for part in broken_parts)

    )

I should expect that it would only add the url_prefix if

• • url_prefix is not empty 
  • and prefix is not empty 
  • and prefix does not start with url_prefix

I suspect that someone who knows the code better than I do would find a cleaner fix.

[Davidiam]

The code for the url above is in core.py

[Davidiam]

The fix that I am using in core.py:

    url_prefix = os.environ.get("PY4WEB_URL_PREFIX", "")

# Fix double url_prefix

    if url_prefix and prefix and prefix.startswith(url_prefix):

        url_prefix = ""

    url = (

        url_prefix

        + prefix

        + "/".join(urllib.parse.quote(part, safe=r":/{}") for part in broken_parts)

    )

On Friday, September 26, 2025 at 5:28:03 PM UTC+2 Davidiam wrote: