Flapping Head

A while back I wrote about using edit inline with image and file fields. Specifically, I suggested adding an uneditable BooleanField as the core field of the related model. This means you don’t have to set the ImageField or FileField to be core (which would cause confusing behaviour).

Removing the related model

The downside to having an uneditable core field is that you can’t remove the related model instance using admin. At the time, I wasn’t trouble by this so I just left it. In a recent project I needed to associate photos with articles, use edit_inline for the photos and be able to remove them. So here’s an extended workaround.

As well as the uneditable BooleanField (“keep”) which keeps the ArticlePhoto from being deleted, we now have a “remove” BooleanField which the user can tick in admin to cause the ArticlePhoto to be deleted. The check for this is in the save() method.

class ArticlePhoto(models.Model):
    article = models.ForeignKey(Article, related_name='photos', edit_inline=models.TABULAR, min_num_in_admin=5)
    keep = models.BooleanField(core=True, default=True, editable=False)
    remove = models.BooleanField(default=False)
    image = CustomImageField()

    def save(self):
        if not self.id and not self.image:
            return
        if self.remove:
            self.delete()
        else:
            super(ArticlePhoto, self).save()

It’s a pretty easy way to work around the problem and gives a sensible looking “remove” checkbox in the admin interface. The database table will have a “remove” column that never gets used, but it’s a pretty small price to pay.

Getting selected text in a Firefox extension

I’m developing a Firefox extension for a client which does something with the currently selected text in the browser window.

The standard way to get the selection is with window.content.getSelection().

Selection is empty in Gmail

Some users reported that selected text in Gmail messages wasn’t being found by the extension. I suspect the issue is with content added using JavaScript, but I haven’t investigated.

An alternative way to getSelection

The standard Search Google for “whatever” contextual menu item does work in Gmail, so obviously it gets the selection another way.

I found a function getBrowserSelection() in the browser.js file in Firefox’s chrome. It is used by Firefox for the contextual menu search.

This is how it gets the selection:

var focusedWindow = document.commandDispatcher.focusedWindow;
var selection = focusedWindow.getSelection();

I don’t know what the difference is, but I am now using this code in my Firefox extension and it is working well.