t-att-value VS t-attf-value on input

[kebeclibre]

Currently we have:

// Sets the props "value" (input.value = val)
<input t-att-value="val" />

// Sets the attribute "value" (input.setAttribute("value", val))
<input t-attf-value="{{ val }}" />

This is highly error prone.

Aim of this issue: harmonize the behavior so that the two ways to write do the same thing.
This is also valid for the other props (readonly, disabled etc....)

linked to opw-4979203

[sdegueldre]

note that ideally we would have a way to set both, as the attribute is used as the default value. In react, the value attribute is set using the defaultValue prop name.

[kebeclibre]

you mean both as in separately ? or together ?

how about t-propf-value="expr" ? (and crashing if the prop is not supported on that Element)
(and t-prop-value of course)

[sdegueldre]

Separately. Sometimes you want to set a default value for an input and if you use t-att-value it will reset the user's input to the default value on every render which is undesirable. Currently the workaround is to use t-attf-value. Making t-attf-value behave like t-att-value will break the workaround. I think regardless of whether the attribute is interpolated or not there should be a way to set both the attribute value and the property value on the underlying DOM element, probably using a different attribute name. I think setting the value on the DOM element is more common than setting the attribute so it should have less friction.