Fix broken default logo image

[klikstermkd]

Fixes #3656

Features:

• includes tests covering changes
• includes updated documentation
• includes user-visible changes
• includes API changes
• includes bugfix for possible backport

[klikstermkd]

Ready for review.

[wardi]

os.isfile can be used instead of a for loop here

[klikstermkd]

@wardi Now it should be good.

[klikstermkd]

@wardi Can you check this again? :)

[amercader]

I think the underlying problem is that the admin form is receiving the correct value (/base/images/ckan-logo.png), even if the widget just displays the file name:

<input id="field-image-url" type="url" name="ckan.site_logo" value="/base/images/ckan-logo.png" placeholder="http://example.com/my-image.jpg" class="form-control" readonly="">

But sending the wrong value to the controllers, it will only send the file name (ckan-logo.png). Rather than adapt the action to this, it would be best to ensure that the form is sending data unchanged.

[klikstermkd]

That still won't resolve the issue because the controller doesn't know whether the default image is uploaded from a user or available already from CKAN's local images directory.

[amercader]

True, but then it's just a matter of covering the local image case in the config_option_update() check:

if key =='ckan.site_logo' and value and not (value.startswith('http') or value.startswith('/')):

[klikstermkd]

Uploaded images from user and CKAN's images from local folder will pass the condition.

[amercader]

Sorry, I meant:

if key =='ckan.site_logo' and value and not value.startswith('http') and not value.startswith('/'):

[klikstermkd]

@amercader Can you check now?