Spatial form: use js callback to webservice to retrieve known spatial extents

[florianm]

What is currently a pre-populated dropdown list (and expensive to load on dataset manage) should be a type-to-autocomplete widget like the tag lookup.

However, we'll need the lookup to have three fields:

• id/name: unique ID
• title: human-readable name (could this be unique?)
• geometry: a simplified(1) geojson multipolygon(2) geometry

(1) because it's only the dataset extent to be picked up in the search, and possibly to be harvested for overviews. Doesn't need super high precision (think coastline with 1000s of vertices).

(2) 'cause that's how we roll.

Challenges:

• build the web service
• populate with data (don't get into mudfights with data custodians over simplified polygons - there's personal pride connected to the number and accuracy of vertices)
• build the callback function (learn from tag callback)
• if tags can store title (with spaces and capitalisation etc) and geometry, populate a named voc from simplified shapefiles of original features (IBRA, IMCRA, NRM regions, townsites, SLIP WMS etc) via script.