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