check response input is json

[mmjjoozz]

https://hellobink.atlassian.net/browse/MER-1958

[backwardspy]

this needs to check content type is application/json before trying to validate the content, otherwise we will lose support for non json responses.

additionally, i can see the appeal of doing this sort of validation for other content types in future. perhaps consider moving the validation into its own function and mapping content types to validators.

perhaps something along these lines:

def is_valid_json(data: str) -> None:
	json.loads(data)

validators = {
	"application/json": is_valid_json,
}

def on_model_change(...):
	if validator := validators.get(form.content_type.data):
		validator(form.content.data)
	super.on_model_change(...)

[Mick-Cadac]

As well as Chris's comment you need to make sure AC2 is covered too. The content field can be left empty, no validation is required for this case.

[backwardspy]

lgtm