226 lines
8.8 KiB
Python
226 lines
8.8 KiB
Python
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"""
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This module is for inspecting OGR data sources and generating either
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models for GeoDjango and/or mapping dictionaries for use with the
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`LayerMapping` utility.
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Author: Travis Pinney, Dane Springmeyer, & Justin Bronn
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"""
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from itertools import izip
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# Requires GDAL to use.
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from django.contrib.gis.gdal import DataSource
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from django.contrib.gis.gdal.field import OFTDate, OFTDateTime, OFTInteger, OFTReal, OFTString, OFTTime
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def mapping(data_source, geom_name='geom', layer_key=0, multi_geom=False):
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"""
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Given a DataSource, generates a dictionary that may be used
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for invoking the LayerMapping utility.
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Keyword Arguments:
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`geom_name` => The name of the geometry field to use for the model.
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`layer_key` => The key for specifying which layer in the DataSource to use;
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defaults to 0 (the first layer). May be an integer index or a string
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identifier for the layer.
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`multi_geom` => Boolean (default: False) - specify as multigeometry.
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"""
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if isinstance(data_source, basestring):
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# Instantiating the DataSource from the string.
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data_source = DataSource(data_source)
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elif isinstance(data_source, DataSource):
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pass
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else:
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raise TypeError('Data source parameter must be a string or a DataSource object.')
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# Creating the dictionary.
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_mapping = {}
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# Generating the field name for each field in the layer.
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for field in data_source[layer_key].fields:
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mfield = field.lower()
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if mfield[-1:] == '_': mfield += 'field'
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_mapping[mfield] = field
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gtype = data_source[layer_key].geom_type
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if multi_geom and gtype.num in (1, 2, 3): prefix = 'MULTI'
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else: prefix = ''
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_mapping[geom_name] = prefix + str(gtype).upper()
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return _mapping
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def ogrinspect(*args, **kwargs):
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"""
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Given a data source (either a string or a DataSource object) and a string
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model name this function will generate a GeoDjango model.
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Usage:
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>>> from django.contrib.gis.utils import ogrinspect
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>>> ogrinspect('/path/to/shapefile.shp','NewModel')
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...will print model definition to stout
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or put this in a python script and use to redirect the output to a new
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model like:
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$ python generate_model.py > myapp/models.py
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# generate_model.py
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from django.contrib.gis.utils import ogrinspect
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shp_file = 'data/mapping_hacks/world_borders.shp'
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model_name = 'WorldBorders'
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print ogrinspect(shp_file, model_name, multi_geom=True, srid=4326,
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geom_name='shapes', blank=True)
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Required Arguments
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`datasource` => string or DataSource object to file pointer
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`model name` => string of name of new model class to create
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Optional Keyword Arguments
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`geom_name` => For specifying the model name for the Geometry Field.
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Otherwise will default to `geom`
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`layer_key` => The key for specifying which layer in the DataSource to use;
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defaults to 0 (the first layer). May be an integer index or a string
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identifier for the layer.
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`srid` => The SRID to use for the Geometry Field. If it can be determined,
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the SRID of the datasource is used.
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`multi_geom` => Boolean (default: False) - specify as multigeometry.
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`name_field` => String - specifies a field name to return for the
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`__unicode__` function (which will be generated if specified).
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`imports` => Boolean (default: True) - set to False to omit the
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`from django.contrib.gis.db import models` code from the
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autogenerated models thus avoiding duplicated imports when building
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more than one model by batching ogrinspect()
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`decimal` => Boolean or sequence (default: False). When set to True
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all generated model fields corresponding to the `OFTReal` type will
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be `DecimalField` instead of `FloatField`. A sequence of specific
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field names to generate as `DecimalField` may also be used.
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`blank` => Boolean or sequence (default: False). When set to True all
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generated model fields will have `blank=True`. If the user wants to
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give specific fields to have blank, then a list/tuple of OGR field
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names may be used.
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`null` => Boolean (default: False) - When set to True all generated
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model fields will have `null=True`. If the user wants to specify
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give specific fields to have null, then a list/tuple of OGR field
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names may be used.
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Note: This routine calls the _ogrinspect() helper to do the heavy lifting.
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"""
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return '\n'.join(s for s in _ogrinspect(*args, **kwargs))
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def _ogrinspect(data_source, model_name, geom_name='geom', layer_key=0, srid=None,
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multi_geom=False, name_field=None, imports=True,
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decimal=False, blank=False, null=False):
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"""
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Helper routine for `ogrinspect` that generates GeoDjango models corresponding
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to the given data source. See the `ogrinspect` docstring for more details.
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"""
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# Getting the DataSource
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if isinstance(data_source, str):
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data_source = DataSource(data_source)
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elif isinstance(data_source, DataSource):
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pass
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else:
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raise TypeError('Data source parameter must be a string or a DataSource object.')
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# Getting the layer corresponding to the layer key and getting
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# a string listing of all OGR fields in the Layer.
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layer = data_source[layer_key]
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ogr_fields = layer.fields
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# Creating lists from the `null`, `blank`, and `decimal`
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# keyword arguments.
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def process_kwarg(kwarg):
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if isinstance(kwarg, (list, tuple)):
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return [s.lower() for s in kwarg]
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elif kwarg:
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return [s.lower() for s in ogr_fields]
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else:
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return []
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null_fields = process_kwarg(null)
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blank_fields = process_kwarg(blank)
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decimal_fields = process_kwarg(decimal)
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# Gets the `null` and `blank` keywords for the given field name.
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def get_kwargs_str(field_name):
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kwlist = []
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if field_name.lower() in null_fields: kwlist.append('null=True')
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if field_name.lower() in blank_fields: kwlist.append('blank=True')
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if kwlist: return ', ' + ', '.join(kwlist)
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else: return ''
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# For those wishing to disable the imports.
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if imports:
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yield '# This is an auto-generated Django model module created by ogrinspect.'
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yield 'from django.contrib.gis.db import models'
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yield ''
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yield 'class %s(models.Model):' % model_name
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for field_name, width, precision, field_type in izip(ogr_fields, layer.field_widths, layer.field_precisions, layer.field_types):
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# The model field name.
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mfield = field_name.lower()
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if mfield[-1:] == '_': mfield += 'field'
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# Getting the keyword args string.
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kwargs_str = get_kwargs_str(field_name)
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if field_type is OFTReal:
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# By default OFTReals are mapped to `FloatField`, however, they
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# may also be mapped to `DecimalField` if specified in the
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# `decimal` keyword.
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if field_name.lower() in decimal_fields:
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yield ' %s = models.DecimalField(max_digits=%d, decimal_places=%d%s)' % (mfield, width, precision, kwargs_str)
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else:
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yield ' %s = models.FloatField(%s)' % (mfield, kwargs_str[2:])
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elif field_type is OFTInteger:
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yield ' %s = models.IntegerField(%s)' % (mfield, kwargs_str[2:])
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elif field_type is OFTString:
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yield ' %s = models.CharField(max_length=%s%s)' % (mfield, width, kwargs_str)
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elif field_type is OFTDate:
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yield ' %s = models.DateField(%s)' % (mfield, kwargs_str[2:])
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elif field_type is OFTDateTime:
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yield ' %s = models.DateTimeField(%s)' % (mfield, kwargs_str[2:])
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elif field_type is OFTDate:
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yield ' %s = models.TimeField(%s)' % (mfield, kwargs_str[2:])
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else:
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raise TypeError('Unknown field type %s in %s' % (fld_type, mfield))
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# TODO: Autodetection of multigeometry types (see #7218).
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gtype = layer.geom_type
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if multi_geom and gtype.num in (1, 2, 3):
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geom_field = 'Multi%s' % gtype.django
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else:
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geom_field = gtype.django
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# Setting up the SRID keyword string.
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if srid is None:
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if layer.srs is None:
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srid_str = 'srid=-1'
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else:
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srid = layer.srs.srid
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if srid is None:
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srid_str = 'srid=-1'
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elif srid == 4326:
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# WGS84 is already the default.
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srid_str = ''
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else:
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srid_str = 'srid=%s' % srid
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else:
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srid_str = 'srid=%s' % srid
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yield ' %s = models.%s(%s)' % (geom_name, geom_field, srid_str)
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yield ' objects = models.GeoManager()'
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if name_field:
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yield ''
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yield ' def __unicode__(self): return self.%s' % name_field
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