Fix issue where config has to be treated as a list of values

[simonw]

Thanks to this code:

datasette-enrichments/datasette_enrichments/views.py

Lines 172 to 173 in 33d0e4b

	config = post_vars._data.copy()
	config.pop("csrftoken", None)

The config dictionary ends up full of things like {"template": ["this is the template"]} which means I have to write code like this:

datasette-enrichments/example-enrichments/jinja_sandbox.py

Lines 61 to 62 in 33d0e4b

	template = env.from_string(config["template"][0])
	output_column = config["output_column"][0]

I did this because I wanted to support the case of a multi-select style interface for selecting a list of items here:

datasette-enrichments/example-enrichments/uppercase.py

Lines 23 to 37 in 33d0e4b

	class ConfigForm(Form):
	columns = MultiCheckboxField("Columns", choices=choices)
	return ConfigForm
	async def enrich_batch(
	self,
	db: Database,
	table: str,
	rows: List[dict],
	pks: List[str],
	config: dict,
	job_id: int,
	):
	columns = config.get("columns") or []

But there should be a better way of doing this - I want config to mostly be single valued keys, with lists only for the keys that need it.

[simonw]

Figured out the right pattern for this - it needs this change:

-    config = post_vars._data.copy()
-    config.pop("csrftoken", None)
+    config = {field.name: field.data for field in form}

Plus this change to that multi column selecting form:

-class MultiCheckboxField(SelectField):
+class MultiCheckboxField(SelectMultipleField):
     widget = ListWidget(prefix_label=False)
     option_widget = CheckboxInput()