Make the source field label configurable when creating a media type

Would it also make sense to be able to adjust the machine name of the auto-created field?

It is often helpful to have a similar Label as machine name. For example if I am making the label of the field be "Flickr Source", I may want the field machine name to be field_flickr_source, instead of field_media_image.

Lets trigger the testbot

I tried to fix all the tests.

I am not 100% sure about the implementation. Do we really need to save the label in the type configuration? I don't see a reason why we would need the label after the form submit. So maybe we should pass the label or the form_state to ::createSourceField() ?

Fixing the last failing test

Turns out that setting the field name in MediaTypeForm is much easier.

Fixed #15

1. +++ b/core/modules/media/src/MediaSourceBase.php
   @@ -193,6 +200,7 @@ public function buildConfigurationForm(array $form, FormStateInterface $form_sta
   +      $form['source_field_label']['#access'] = FALSE;
   

   Why should we restrict access to the label on edit? Also if this is important it is not tested.

2. +++ b/core/modules/media/src/MediaTypeForm.php
   @@ -341,7 +341,8 @@ public function save(array $form, FormStateInterface $form_state) {
   +        ->set('label', $form_state->getValue(['source_configuration', 'source_field_label']), $source->getPluginDefinition()['label']);
   

   ->set() only takes tow arguments. $form_state->getValue() can take two and that is probably what was meant to happen here but also I'm not sure it is needed because the field value is defaulted to this already.

3. +++ b/core/modules/media/tests/src/FunctionalJavascript/MediaTypeCreationTest.php
   @@ -21,6 +21,7 @@ public function testMediaTypeCreationFormWithDefaultField() {
   +    $sourceFieldLabel = 'Wambooli';
   

   Camel case is not used for local variables.

Thanks for reviewing @alexpott

1. The new form field is only for setting the initial label. It makes no sense to have the form field after the creation. If you want to change the label later, you can use the normal field config form. I added a test.

2. Nice catch 👍Fixed it and I still think it's useful. If the form value is empty for some reason, we still have a valid value and not an empty label.

3. Fixed.

I think we need a UX review here. Things like #2557299: Any AJAX call disregards machine name verification when AJAX is used and leads to a fatal error do not make reviewing the UX of the media type creation process simple but I think we should think about the default names of the media field more carefully because:

• The new field appears on the media type creation form - which is the same as the edit form - but it is not present on the edit form. That's because it is only used during creation of the field added to the media type but that's confusing because a user doesn't learn where to change this. If we want to having this there then in my opinion we should also have it on the edit form and make it work by updating the field on media type save.
• BUT the default field names are dubious because if I create a new media type with a type of image I can make it store the data in an existing field called field_media_video_file?!!??! I wish that the initial label and field name was Media/media

so not using the user created field prefix of field_

I found this issue while running into frustrations around the machine names created during media type creation. This is the first site I've attempted to build from scratch using media reference fields in place of image fields that I may have used in the past.

Because image constraints (primarily minimum width and height, but fundamentally everything on the image field instance settings form) vary per (what would have been an) image field, I find it necessary to create a media type for each image field I'm replacing, which quickly becomes a dozen or so image media types. I would like to use some sort of sensible machine name for the source field for each type, but if I create one, I'm stuck with field_media_image_7, field_media_image_12, ect. Since I want them to be unique to this new media type, they aren't existing.

The only workaround I'm finding is to have a dummy media type in the beginning that I can use to pre-create the fields with useful machine names (field_header_image, field_profile_icon_image, etc), which then allows me to create new media type using the 'existing fields'. Once Development is done, I can delete the originally dummy media type.