Selecting layout objects with slices doesn't work ('LayoutSlice' object is not subscriptable)

[Sulfyderz]

• Package version: 1.14.0
• Django version: 4.1.3
• Python version: 3.10.4
• Template pack: bootstrap5

Description:

Hello,

There is a bug with the helper when we want to update the layout on the go.
I have this layout in my form __init__ method:

self.helper.layout = Layout(
            Div(
                Div(
                    HTML('<ul id="ul-id-member">'),
                    HTML("</ul>"),
                    BaseInput(
                        "input-member",
                        "",
                        css_id="input-id-member",
                        hx_include="#ul-id-member",
                        hx_target="#member-suggestions",
                        hx_trigger="focus changed, newMemberSearch from:body delay:200ms",
                        hx_swap="innerHTML",
                        hx_get="",
                    ),
                    css_class="member-tag",
                ),
                HTML('<ol id="member-suggestions" class="member-suggestions"></ol>'),
                css_class="member-invite",
            ),
            Field("role", id="select-id-role"),
            Submit("invite", "Invite"),
            Button("cancel", "Cancel"),
        )

I would like to access the BaseInput as described in the doc. Unfortunately, it doesn't work at all. When I try form.helper[0][0][-1] in my view, Python tells me that TypeError: 'LayoutSlice' object is not subscriptable.

Not sure, but I think it's a bug. Could you help me ?

[smithdc1]

I think it's the [-1] that's not supported. Does [0][1] work for you?

[Sulfyderz]

Hello,

No, it doesn't work.
I tried these :

>>> form.helper[0][0] # Should select the nested Div
>>> form.helper[0][1]  # Should select the nested HTML

Then I got this :

Traceback (most recent call last):
  File "<console>", line 1, in <module>
TypeError: 'LayoutSlice' object is not subscriptable

If I use form.helper.layout[0][0][1] instead of form.helper[0][0][-1] to select my BaseInput, it works but it's not a LayoutSlice object. Thus, I don't have the update_attributes method. If I use form.helper[1] however, I do have that method. It seems form.helper only works for non nested objects (e.g. form.helper[0] works, I do have a LayoutSlice object). Could you help?

[Sulfyderz]

Well, I found something interesting. It's somehow related to my other issue #1327. Since I can't have any LayoutSlice for nested objects, I can't have the related methods such as update_attributes.

What could be great is not to have that question in mind: "Should I use form.helper[0] or form.helper.layout[0] ?". Both should have the same methods. What do you think @smithdc1 ?

[Sulfyderz]

Hello again,

After checking your code, I know why it doesn't work. Your LayoutSlice doesn't have a __getitem__ method. That's why you can only have first-level layout elements with LayoutSlice. Moreover, you are right about -1 as an indice, form.helper[-1].update_attributes do not work at all.

I tried to change/update your code to PR but I didn't get your interest with the slice as follow :

class LayoutSlice:
    # List of layout objects that need args passed first before fields
    args_first = (Fieldset, MultiField, Container)

    def __init__(self, layout, key):
        self.layout = layout
        if isinstance(key, int):
            self.slice = slice(key, key + 1, 1)
        else:
            self.slice = key

Almost all other methods in your LayoutSlice use that. A simpler way is to remove it. If you can share your agenda to have chosen that way, I could help.