You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
225 lines
8.8 KiB
225 lines
8.8 KiB
""" |
|
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 OFTDate: |
|
yield ' %s = models.TimeField(%s)' % (mfield, kwargs_str[2:]) |
|
else: |
|
raise TypeError('Unknown field type %s in %s' % (fld_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
|
|
|