wiki:BluePrint/GIS/LocationSelector

Version 10 (modified by Fran Boon, 11 years ago) ( diff )

S3LocationSelector work-in-progress

Location Selector

We want a widget which can be embedded within a form to be able to select the appropriate location to associate with a record using either hierarchical dropdowns or a precise location.

Status

We have a widget in views/gis/location_autocomplete.js

  • this is added manually to many view templates (often this is the only customisation for that view)

This supports:

  • Hierarchical Level selector to choose the correct level or select the correct Parent
    • The country selector remains hidden if there is only 1 country being used (as per deployment_settings).
    • The number of levels available depends on the deployment_settings.
    • Initially just a single dropdown is displayed.
    • When this dropdown is selected then the next dropdown is displayed, along with appropriate values
      • We download the values via AJAX in order to not have to download all Locations
  • The user has the option of adding a more specific Name & a Street Address
    • This is not mandatory as some records need to link directly to the L0-L4 levels.
    • New locations have their name automatically set from that of the Record, if no other name is provided
  • Geocoder lookup of a Street Address
  • Map-based lookup of Lat/Lon
  • Manual entry of of Lat/Lon (either from a GPS or looked up in an online resource like Wikipedia)
    • A Conversion tool is available to convert from Deg/Min/Sec to Decimal Degrees

ToDo

  • Move the implementation to a server-side widget so that it applies automatically to all instances of the field (can then remove from custom view templates)
    • Work has started on this: S3LocationSelector in modules/widgets.py & static/scriptsS3/s3.locationselector.widget.js.
      Enable by uncommenting in models/03_gis.py & comment the old autocomplete in a view to try it out (e.g. views/cr/shelter_autocompletes.html).
  • Increase Robustness (currently there are many bugs)
  • Redesign the Look/Feel to make it more usable
    • Display all the Lx layer dropdowns from the start?
    • Hide the 'Add New Location' options behind a button (CSS Hide)
    • Hide the Lat/Lon entry forms behind an 'Advanced' button (CSS Hide)
    • Don't load the Map within the page but do this as a separate server-side call
  • Make it work with components (see below)
  • Add an HTML5 GeoLocation option ('Current Location')
    • we should use a 'nearby' algorithm (like gis.get_features_in_radius()) to re-use existing locations rather than adding a new one each time.
    • e.g. pr/person/presence could be recorded automatically upon login
  • Set the map entry default lat/lon/zoom based on the selected Level in the Hierarchy (assumes we have at least Centroid information available, ideally use Polygons where we have them)
  • Display the geocoder results on a map for visual confirmation that the correct result has been returned
  • Use more Geocoders than just Google
  • If we have admin boundaries available then the Lat/Lon provided can be validated against the selected Lat/Lon
  • If we have admin boundaries available then the correct hierarchy can be filled-in automatically if just the Lat/Lon are provided
  • Experiment with downloading all Locations at startup (into a jQuery Data store) & filtering client-side, or maybe downloading just the full next level of hierarchy proactively (e.g. we've got the L0 selected, we have the L1 dropdown populated accordingly...we could download *all* L2s within the L0 ready for when the L1 is selected & then filter the downloaded L2 data to those within the relevant L1 to populate the L2 dropdown with). This would also provide an automatic cache (within the page only).
  • Extend the location_id() API to support controlling which levels of hierarchy we're interested in for a resource (some may be only interested in the province, whereas others may need a precise location)

Known Issues

There are various bugs in the current implementation, some of which are listed below.

Duplication of location records

This happens when you for example create a new hospital record without creating a new location, but just selecting one (just select a country, for example). When you submit, then a new location record is created with the same name as the selected one - this seems wrong. You can make it visible by uncommenting the show_status line. The reason for this behaviour is that S3.gis.uuid is empty in case there is no old_location, which triggers the creation of a new record. Thus, this does not happen in update, and not either when you create a new location (which creates a new location anyway :D).

Use in Component Forms

To be able to apply the location selector to components (e.g. person/presence, where it would be *very* useful), we need to go away from the 'request.controller + "_" + request_function' construction and instead use jr.

Perhaps this way:

 {{try:}}
   var location_id = '{{=jr.prefix + "_" + jr.target()[1] + "_location_id"}}';
 {{except:}}
   var location_id = '{{=request.controller + "_" + request.function + "_location_id"}}';
 {{pass}}

PakistanDevelopers#LocationsSelector

BluePrintGISLocationsHierarchy

GIS BluePrints

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