[5.2] Allow nested Subform inside a Subform Custom Field

[AndySDH]

Summary of Changes

When creating a custom field of type Subform, you can select the child fields that you want as part of the Subform.

In the current situation, the dropdown of fields selection doesn't allow to select a Subform to be nested inside a Subform. This was probably done to avoid cluttering the interface too much if somebody wanted to do it.

But there is a legimitate use for this and somebody may want to intentionally have a nested Subform inside a Subform. I am currently having a legitimate use case where I want a Subform inside a Subform and I can't do it because of this limitation. There is no reason to have this limitation, let the user do it if they want to.

Testing Instructions

• Go to Content -> Fields
• Make sure you already have a bunch of created fields, as well as a Subform field already created
• Create a new field of type Subform
• Look at the "Fields" area to see what child fields you can include with the dropdown

Actual result BEFORE applying this Pull Request

• A field of type subform is not in the available list of fields in the dropdown

Expected result AFTER applying this Pull Request

• A field of type subform now is available to be selected

Link to documentations

• No documentation changes for docs.joomla.org needed

[AndySDH]

@richard67 Thanks, fixed!

[regularlabs]

Seems to do the job.
Test successful ✅

[richard67]

Seems to do the job. Test successful ✅

@regularlabs Could you please mark your test result in the issue tracker? For this go to https://issues.joomla.org/tracker/joomla-cms/43204 and use the blue "Test this" button at the top left corner, then select your test result and finally submit. Thanks in advance.

[regularlabs]

I have tested this item ✅ successfully on 041cd38

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[Quy]

I have tested this item ✅ successfully on 041cd38

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43204.}

[Quy]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43204.}

[AndySDH]

Thanks guys!

[HLeithner]

Is an endless loop considered here? subform1 -> subform2 -> subform1

I don't think so, so maybe we should check for recursion at some point (rendering or saving)

[AndySDH]

It's not considered, but then again, that would be the user that purposely breaks the form by doing something like that. It's not different then embedding a module inside another module which embeds the module itself, etc. I don't think we need to cover the case where the user does something dumb

[pe7er]

Thanks @AndySDH !