downcastAttributeToElement does not support downcasting from specified model element

[scofalik]

downcastAttributeToAttribute converter lets us specify from which model element the attribute is converted. This is an example configuration:

downcastAttributeToAttribute( {
	model: {
		name: 'image',
		key: 'source'
	},
	view: 'src'
} );

In this case, source attribute is converted only from images.

The same is not possible with downcastAttributeToElement. There are two things we can do now:

1. Assume that this kind of conversion always happens for $text. This is quite a rational assumption given that the converter uses wrap converter which is meant to wrap parts of view in AttributeElement. I don't know if there's any other real case. Maybe if we will add inline elements or something.

2. Provide support for name in config.

[pjasiun]

2

[Reinmar]

What will this converter do? What kind of element will it create and what's the use case in general?

[scofalik]

It doesn't matter what kind of element will it create because we are talking here about model part of config, so about the part that is converted (and consumed).

In short, we are deciding whether we should give control over the event name to which the converter will be added. It could be attribute:attrName or attribute:attrName:elementName. In the second case, only attrName set on elementName will be converted.

We could also hardcode $text in the place of elementName, but then the inline features (like for example smileys) would not be wrapped (so a smiley might break a link, for example). So we should definitely go with solution 2. as it is future-proof.

We'd like following to work (suppose thereotical smiley plugin):

<$text linkHref="foo.html>foo</$text>
<smiley name="smile" linkHref="foo.html"></smiley>
<$text linkHref="bar.html">bar</$text>

🔽

<a href="foo.html>foo<img src="smile.jpg"></img>bar</a>

So we cannot hardcode that attributeToElement conversion is only for $text.