Source Code for Module madrona.shapes.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      # TODO: 
 18      # collect attribute info to stick in potential model 
 19      #title = forms.CharField(max_length=50,label=_('Title')) 
 20      #epsg = forms.IntegerField() 
 21   
 22 -    def clean_file_obj(self): 
 23          f = self.cleaned_data['file_obj'] 
 24          valid_shp, error = self.validate(f) 
 25          if not valid_shp: 
 26              raise ValidationError("A problem occured: %s" % error) 
 27   
 28 -    def handle(self,filefield_data): 
 29          """ Upload the file data, in chunks, to the SHP_UPLOAD_DIR specified in settings.py. 
 30          """ 
 31          # ensure the upload directory exists 
 32          if not os.path.exists(settings.SHP_UPLOAD_DIR): 
 33              os.makedirs(settings.SHP_UPLOAD_DIR)  
 34   
 35          # contruct the full filepath and filename 
 36          downloaded_file = os.path.normpath(os.path.join(settings.SHP_UPLOAD_DIR, filefield_data.name)) 
 37   
 38          print downloaded_file 
 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('%d%m%Y_%m') 
 43              downloaded_file = '%s_%s%s' % (name,append,ext)  
 44   
 45          print downloaded_file 
 46          # write the zip archive to final location 
 47          self.write_file(downloaded_file,filefield_data) 
 48   
 49 -    def write_file(self,filename,filefield_data): 
 50          destination = open(filename, 'wb+') 
 51          for chunk in filefield_data.chunks(): 
 52              destination.write(chunk) 
 53          destination.close()         
 54   
 55 -    def check_zip_contents(self, ext, zip_file): 
 56          if not True in [info.filename.endswith(ext) for info in zip_file.infolist()]: 
 57              return False 
 58          return True 
 59   
 60 -    def validate(self,filefield_data): 
 61          """ Validate the uploaded, zipped shapefile by unpacking to a temporary sandbox. 
 62          """ 
 63          # create a temporary file to write the zip archive to 
 64          tmp = tempfile.NamedTemporaryFile(suffix='.zip', mode='w') 
 65   
 66          # write zip to tmp sandbox 
 67          self.write_file(tmp.name,filefield_data) 
 68   
 69          if not zipfile.is_zipfile(tmp.name): 
 70              return False, 'That file is not a valid Zip Archive' 
 71   
 72          # create zip object 
 73          zfile = zipfile.ZipFile(tmp.name) 
 74   
 75          # ensure proper file contents by extensions inside 
 76          if not self.check_zip_contents('shp', zfile): 
 77              return False, 'Found Zip Archive but no file with a .shp extension found inside.' 
 78          elif not self.check_zip_contents('prj', zfile): 
 79              return False, 'You must supply a .prj file with the Shapefile to indicate the projection.' 
 80          elif not self.check_zip_contents('dbf', zfile): 
 81              return False, 'You must supply a .dbf file with the Shapefile to supply attribute data.' 
 82          elif not self.check_zip_contents('shx', zfile): 
 83              return False, 'You must supply a .shx file for the Shapefile to have a valid index.' 
 84   
 85          # unpack contents into tmp directory 
 86          tmp_dir = tempfile.gettempdir() 
 87          for info in zfile.infolist(): 
 88              data = zfile.read(info.filename) 
 89              shp_part = '%s%s%s' % (tmp_dir,os.path.sep,info.filename) 
 90              fout = open(shp_part, "wb") 
 91              fout.write(data) 
 92              fout.close() 
 93   
 94          # get the datasource name without extension 
 95          ds_name = os.path.splitext(zfile.namelist()[0])[0] 
 96   
 97          # ogr needs the full path to the unpacked 'file.shp' 
 98          ds = gdal.DataSource('%s%s%s.shp' % (tmp_dir,os.path.sep,ds_name)) 
 99   
100          # shapefiles have just one layer, so grab the first... 
101          layer = ds[0] 
102   
103          # one way of testing a sane shapefile... 
104          # further tests should be able to be plugged in here... 
105          if layer.test_capability('RandomRead'): 
106              if str(ds.driver) == 'ESRI Shapefile': 
107                  return True, None 
108              else: 
109                  return False, "Sorry, we've experienced a problem on our server. Please try again later." 
110          else: 
111              return False, 'Cannot read the shapefile, data is corrupted inside the zip, please try to upload again' 
112