Source Code for Module madrona.loadshp.forms

  1  import os 
  2  import zipfile 
  3  import tempfile 
  4  import datetime 
  5  from django import forms 
  6  from django.forms.util import ValidationError 
  7  from django.utils.translation import ugettext_lazy as _ 
  8  from django.conf import settings 
  9  from django.contrib.gis import gdal 
 10   
 11  #http://docs.djangoproject.com/en/dev/topics/http/file-uploads/ 
 12  #http://www.neverfriday.com/sweetfriday/2008/09/-a-long-time-ago.html  
 13   
 14 -class UploadForm(forms.Form): 
 15   
 16      file_obj = forms.FileField(label='Upload a Zipped Shapefile') 
 17      multi_feature = True 
 18      supported_geomtypes = ['Polygon','Point','Line'] 
 19      enforce_4326 = True 
 20   
 21 -    def clean_file_obj(self): 
 22          f = self.cleaned_data['file_obj'] 
 23          valid_shp, error = self.validate(f) 
 24          if not valid_shp: 
 25              raise ValidationError("A problem occured: %s" % error) 
 26   
 27 -    def handle(self,filefield_data,user): 
 28          """ Upload the file data, in chunks, to the media/upload/loadshp. 
 29              Then unpack it, read the features and return them 
 30          """ 
 31          # ensure the upload directory exists 
 32          upload_dir = os.path.join(settings.MEDIA_ROOT,'upload','loadshp',user.username) 
 33          if not os.path.exists(upload_dir): 
 34              os.makedirs(upload_dir)  
 35   
 36          # contruct the full filepath and filename 
 37          downloaded_file = os.path.normpath(os.path.join(upload_dir, filefield_data.name)) 
 38   
 39          # if we've already got an upload with the same name, append the daymonthyear_minute 
 40          if os.path.exists(downloaded_file): 
 41              name, ext = os.path.splitext(downloaded_file) 
 42              append = datetime.datetime.now().strftime('%Y%m%d_%H%M%S') 
 43              downloaded_file = '%s_%s%s' % (name,append,ext)  
 44   
 45          # write the zip archive to final location 
 46          self.write_file(downloaded_file,filefield_data) 
 47   
 48          #unpack the files 
 49          zfile = zipfile.ZipFile(downloaded_file) 
 50          tmp_dir = tempfile.gettempdir() 
 51          for info in zfile.infolist(): 
 52              data = zfile.read(info.filename) 
 53              shp_part = '%s%s%s' % (tmp_dir,os.path.sep,info.filename) 
 54              fout = open(shp_part, "wb") 
 55              fout.write(data) 
 56              fout.close() 
 57   
 58          # get the datasource name without extension 
 59          ds_name = os.path.splitext(zfile.namelist()[0])[0] 
 60          ds = gdal.DataSource('%s%s%s.shp' % (tmp_dir,os.path.sep,ds_name)) 
 61          return ds[0] 
 62   
 63 -    def write_file(self,filename,filefield_data): 
 64          destination = open(filename, 'wb+') 
 65          for chunk in filefield_data.chunks(): 
 66              destination.write(chunk) 
 67          destination.close()         
 68   
 69 -    def check_zip_contents(self, ext, zip_file): 
 70          if not True in [info.filename.endswith(ext) for info in zip_file.infolist()]: 
 71              return False 
 72          return True 
 73   
 74 -    def validate(self,filefield_data): 
 75          """ Validate the uploaded, zipped shapefile by unpacking to a temporary sandbox. 
 76          """ 
 77          # create a temporary file to write the zip archive to 
 78          tmp = tempfile.NamedTemporaryFile(suffix='.zip', mode='w', delete=False) 
 79   
 80          # write zip to tmp sandbox 
 81          self.write_file(tmp.name,filefield_data) 
 82   
 83          if not zipfile.is_zipfile(tmp.name): 
 84              return False, 'That file is not a valid Zip Archive' 
 85   
 86          # create zip object 
 87          zfile = zipfile.ZipFile(tmp.name) 
 88   
 89          # ensure proper file contents by extensions inside 
 90          if not self.check_zip_contents('shp', zfile): 
 91              return False, 'Found Zip Archive but no file with a .shp extension found inside.' 
 92          elif not self.check_zip_contents('dbf', zfile): 
 93              return False, 'You must supply a .dbf file with the Shapefile to supply attribute data.' 
 94          elif not self.check_zip_contents('shx', zfile): 
 95              return False, 'You must supply a .shx file for the Shapefile to have a valid index.' 
 96   
 97          # unpack contents into tmp directory 
 98          tmp_dir = tempfile.gettempdir() 
 99          for info in zfile.infolist(): 
100              data = zfile.read(info.filename) 
101              shp_part = '%s%s%s' % (tmp_dir,os.path.sep,info.filename) 
102              fout = open(shp_part, "wb") 
103              fout.write(data) 
104              fout.close() 
105   
106          # get the datasource name without extension 
107          ds_name = os.path.splitext(zfile.namelist()[0])[0] 
108   
109          # ogr needs the full path to the unpacked 'file.shp' 
110          ds = gdal.DataSource('%s%s%s.shp' % (tmp_dir,os.path.sep,ds_name)) 
111   
112          # shapefiles have just one layer, so grab the first... 
113          layer = ds[0] 
114   
115          # one way of testing a sane shapefile... 
116          # further tests should be able to be plugged in here... 
117          if layer.test_capability('RandomRead'): 
118              if str(ds.driver) != 'ESRI Shapefile': 
119                  return False, "Sorry, we've experienced a problem on our server. Please try again later." 
120          else: 
121              return False, 'Cannot read the shapefile, data is corrupted inside the zip, please try to upload again' 
122   
123          # Must have a prj or have data in the -180,-90,180,90 window (assumed to be latlong) 
124          if not self.check_zip_contents('prj', zfile) and (layer.extent.min_x < -180.0 or layer.extent.max_x > 180.0 \ 
125                 or layer.extent.min_y < -90.0 or layer.extent.max_y > 90.0): 
126              return False, 'You must supply a .prj file with the Shapefile to indicate the projection.' 
127          else: 
128              g = layer[0].geom 
129              if g.srs: 
130                  g.transform_to(4326) 
131              ext = g.envelope 
132              if ext.min_x < -180.0 or ext.max_x > 180.0 or ext.min_y < -90.0 or ext.max_y > 90.0: 
133                  return False, 'There was an error reprojecting your geometry. You must supply a .prj file or reproject to WGS84.' 
134   
135          if layer.geom_type.name not in self.supported_geomtypes: 
136              return False, "Sorry, %s geometries are not supported. Try uploading a zipped shapefile with %s geometries" % \ 
137                      (layer.geom_type.name, ', '.join(self.supported_geomtypes)) 
138   
139          if not self.multi_feature and layer.num_feat != 1: 
140              return False, "We can only support shapefiles with a single feature" 
141   
142          return True, "Shapefile is good to go" 
143