BuilderListItemFactory, using gtkexpression to set the style class

[emmanueltouzery]

I'm using BuilderListItemFactory to have dynamic GtkListItems. It's working fine to set a GtkLabel label as in the example. However I would use that to apply a (potentially) different style class name to every list item.

Here's what I did:

<?xml version="1.0" encoding="UTF-8"?>
<interface>
  <template class="GtkListItem">
    <property name="child">
      <object class="GtkLabel">
        <!-- <property name="css-classes">project-item-prod</property> -->
        <binding name="css-classes">
          <lookup name="environmentcss" type="ProjectItemModel">
            <lookup name="item">GtkListItem</lookup>
          </lookup>
        </binding>
        <binding name="label">
          <lookup name="title" type="ProjectItemModel">
            <lookup name="item">GtkListItem</lookup>
          </lookup>
        </binding>
      </object>
    </property>
  </template>
</interface>

Note that setting the css-classes property using the commented code works fine.

    #[derive(Properties, Default)]
    #[properties(wrapper_type = super::ProjectItemModel)]
    pub struct ProjectItemModel {
        #[property(get, set)]
        title: Rc<RefCell<String>>,
        #[property(get, set)]
        environmentcss: Rc<RefCell<String>>,
    }

Now that compiles, but at runtime, I get:

GLib-GObject-CRITICAL **: 22:11:59.926: unable to set property 'css-classes' of type 'GStrv' from value of type 'gchararray'

It actually would seem (probably naively) that I'm not too far... If only I could explicitly say that the type of my model property should be GStrv and not gchararray, then it should work, right? Except I'm afraid it's probably quite a lot more complicated than that :(

So, is this at all possible? 😬

[emmanueltouzery]

Ok, i got it, for GStrv, the type of the property should be Vec<String> instead of String. Then it works just fine.

I got confused by the fact that when you specify the value by hand, you give a single newline-separated string. And I didn't look too closely at the C alias for GStrv, which is a double pointer, and so doesn't explicitely say it contains an array (like it would with a [] marker for instance).