# Django 2.2.9.dev20191202104323 文档

# GeoDjango Forms API

GeoDjango provides some specialized form fields and widgets in order to visually display and edit geolocalized data on a map. By default, they use OpenLayers-powered maps, with a base WMS layer provided by NASA.

## Field arguments

In addition to the regular form field arguments, GeoDjango form fields take the following optional arguments.

### `srid`

`Field.``srid`

  This is the SRID code that the field value should be transformed to. For example, if the map widget SRID is different from the SRID more generally used by your application or database, the field will automatically convert input values into that SRID.

### `geom_type`

`Field.``geom_type`

  You generally shouldn't have to set or change that attribute which should be setup depending on the field class. It matches the OpenGIS standard geometry name.

## Form field classes

### `GeometryField`

class `GeometryField`

### `PointField`

class `PointField`

### `LineStringField`

class `LineStringField`

### `PolygonField`

class `PolygonField`

### `MultiPointField`

class `MultiPointField`

### `MultiLineStringField`

class `MultiLineStringField`

### `MultiPolygonField`

class `MultiPolygonField`

### `GeometryCollectionField`

class `GeometryCollectionField`

## Form widgets

GeoDjango form widgets allow you to display and edit geographic data on a visual map. Note that none of the currently available widgets supports 3D geometries, hence geometry fields will fallback using a simple `Textarea` widget for such data.

### Widget attributes

GeoDjango widgets are template-based, so their attributes are mostly different from other Django widget attributes.

`BaseGeometryWidget.``geom_type`

  The OpenGIS geometry type, generally set by the form field.

`BaseGeometryWidget.``map_height`

`BaseGeometryWidget.``map_width`

  Height and width of the widget map (default is 400x600).

`BaseGeometryWidget.``map_srid`

  SRID code used by the map (default is 4326).

`BaseGeometryWidget.``display_raw`

  Boolean value specifying if a textarea input showing the serialized representation of the current geometry is visible, mainly for debugging purposes (default is `False`).

`BaseGeometryWidget.``supports_3d`

  Indicates if the widget supports edition of 3D data (default is `False`).

`BaseGeometryWidget.``template_name`

  The template used to render the map widget.

You can pass widget attributes in the same manner that for any other Django widget. For example:

    from django.contrib.gis import forms

    class MyGeoForm(forms.Form):
        point = forms.PointField(widget=
            forms.OSMWidget(attrs={'map_width': 800, 'map_height': 500}))

### Widget classes

`BaseGeometryWidget`

class `BaseGeometryWidget`

  This is an abstract base widget containing the logic needed by subclasses. You cannot directly use this widget for a geometry field. Note that the rendering of GeoDjango widgets is based on a template, identified by the `template_name` class attribute.

`OpenLayersWidget`

class `OpenLayersWidget`

  This is the default widget used by all GeoDjango form fields. `template_name` is `gis/openlayers.html`.

  `OpenLayersWidget` and `OSMWidget` use the `openlayers.js` file hosted on the `cdnjs.cloudflare.com` content-delivery network. You can subclass these widgets in order to specify your own version of the `OpenLayers.js` file in the `js` property of the inner `Media` class (see 资源作为静态定义).

`OSMWidget`

class `OSMWidget`

  This widget uses an OpenStreetMap base layer to display geographic objects on. Attributes are:

  `template_name`

    `gis/openlayers-osm.html`

  `default_lat`
  `default_lon`

    The default center latitude and longitude are `47` and `5`, respectively, which is a location in eastern France.

  `default_zoom`

    The default map zoom is `12`.

  The `OpenLayersWidget` note about JavaScript file hosting above also applies here. See also this FAQ answer about `https` access to map tiles.