Contextual combo box bug

[grahame]

Steps to reproduce:

• add a contextual filter with a combo box (e.g. Australian Soil Classification)
• leave as defaults
• press the search button
• error will be shown

I've investigated, the underlying issue appears to be that when we emit selectContextualFilter we add a clone of EmptyContextualFilter to the redux store. This doesn't actually match what we're displaying in the UI - in the UI we're showing the first combo box option as being selected.

I'm not sure the best approach to fix this. We'll probably need a different template EmptyContextualFilter for each type of filter (string, combo box / ontology, float range, ...)

@sztamas when you're back could you maybe suggest a fix?

[sztamas]

After the changes to the import process, the ontologies return the no selection value item with an id of 0.

Changing the value of the select option to be the empty string instead, to stay consistent with the other contextual filters. ie. sending an empty string to the server means the user selected a contextual filter but hasn't selected/entered a value for the filter.

[sztamas]

@grahame this has been fixed.