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GeoFormAlchemy - a extension for FormAlchemy that adds support for spatial databases

Project description

GeoFormAlchemy is an extension for FormAlchemy that makes it possible to generate forms for model classes that use the geometry types of GeoAlchemy.


Requires FormAlchemy and GeoAlchemy >=0.4.


Installing using easy_install:

$ easy_install geoformalchemy

Manual installation for development:

Download the source code as archive or clone the GIT repository:

git clone GeoFormAlchemy

Then run the setup:

cd GeoFormAlchemy/GeoFormAlchemy
python develop

Usage in Pylons applications

GeoFormAlchemy includes a Paster Pylons template that builds upon FormAlchemy’s administration interface for Pylons.

If you want to use GeoFormAlchemy in your Pylons application, run paster create with the GeoFormAlchemy template:

$ paster create -t geo_fa your_app
Enter admin_controller (Add formalchemy's admin controller) [False]: True
Enter template_engine (mako/genshi/jinja2/etc: Template language) ['mako']: mako
Enter sqlalchemy (True/False: Include SQLAlchemy 0.5 configuration) [False]: True

Then the GeoFormAlchemy extension has to be activated. Open the file your_app/forms/ and add the following lines at the end of the file:

# [..]

from geoformalchemy.base import GeometryFieldRenderer
from geoalchemy import geometry
FieldSet.default_renderers[geometry.Geometry] = GeometryFieldRenderer

GeoFormAlchemy is now set up and a map will be displayed in the forms for your geometry fields. Note that you will have to tell FormAlchemy for which model classes it should create forms. To do so import your model classes in the file your_app/model/ For more information please refer to the FormAlchemy documentation.


Field modifications

The rendering of geometry fields can be customized with additional options. For example the following statement called on the field the_geom of the custom FieldSet changes the background map (inside the file your_app/forms/

Place = FieldSet(model.places.Place)
    ('map_srid', 900913),
    ('base_layer', 'new OpenLayers.Layer.OSM("OSM")')

The following options are available in GeoFormAlchemy:

default_lat and default_lon

If the geometry is None or when creating a new geometry, the map is centered at (default_lon, default_lat). Otherwise the map is centered at the centroid of the geometry.


The zoom-level on start-up.

map_width and map_height

The size of the DIV container in which the map is displayed.


The OpenLayers layer which will be used as background map, for example:

('base_layer', 'new OpenLayers.Layer.OSM("OSM")')

If the map uses a different CRS than the geometries, the geometries will be reprojected to this CRS. For example:

('map_srid', 900913)

The path to the OpenLayers JavaScript library, for example if OpenLayers.js is located at your_app/public/js/lib/OpenLayers.js use the following path:

('openlayers_lib', '/js/lib/OpenLayers.js')
show_map (default: True)

If show_map is set to False, the geometry will be displayed as WKT string inside a text input field.

insert_libs (default: True)

If insert_libs is set to False, the OpenLayers and GeoFormAlchemy JavaScript libs are not loaded in the page, nor is the default CSS for GeoFormAlchemy. If insert_libs is set to False the application developer is responsible for adding script and style tags for OpenLayers and GeoFormAlchemy. You’ll set insert_libs to False if you have multiple map fields, or if you want to delay the loading of the JS code until after the page is loaded.

run_js (default: True)

If run_js is set to False, The call to geoformalchemy.init_map() is not done. You can call it manually with fs.render_fields['the_geom'].renderer.render_runjs(). You’ll set run_js to False if you want to delay the initialization of the map until after the page is loaded. If you want to set run_js to False you probably also want to set insert_libs to False.

Template files

If you want to change the look of your forms, you can modify the template files used by FormAlchemy and GeoFormAlchemy. The template files are located in the folder your_app/templates/forms.

GeoFormAlchemy uses the template files map_js.mako and map.mako. In map.mako you can set most of the options that you can also use as field modification. But unlike to field modifications, the options set in the template file are used for the geometry fields of all models, whereas the options set as field modification are only used for the field they were set on.

# default configuration options that will be used when
# no field options were set

options = {}
options['default_lon'] = 10
options['default_lat'] = 45
options['zoom'] = 4
options['map_width'] = 512
options['map_height'] = 256
options['base_layer'] = 'new OpenLayers.Layer.WMS("WMS", "", {layers: "basic"})'
options['openlayers_lib'] = ''


If you want to customize the OpenLayers map, for example to add a further OpenLayers control or to add a second background layer, modify the file map_js.mako.

Project details

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GeoFormAlchemy-0.4.tar.gz (15.4 kB view hashes)

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