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1 """This module contains a function to upload an image file to a S3Bucket.
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2
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3 The image can be resized and a thumbnail can be generated and uploaded as well.
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4
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5 """
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6 import logging
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7 from io import BytesIO
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8 import os.path
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9 import tempfile
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10 import uuid
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11
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12 from PIL import Image
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13
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14 from core.functions import temp_open
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15
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16
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17 logger = logging.getLogger(__name__)
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18
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19
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20 def upload(fp, bucket, metadata=None, new_size=None, thumb_size=None):
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21 """Upload an image file to a given S3Bucket.
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22
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23 The image can optionally be resized and a thumbnail can be generated and
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24 uploaded as well.
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25
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26 Parameters:
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27 fp - The image file to process. This is expected to be an instance of
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28 Django's UploadedFile class. The file must have a name attribute and
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29 we expect the name to have an extension. This is extension is
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30 used for the uploaded image and thumbnail names.
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31 bucket - A core.s3.S3Bucket instance to upload to.
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32 metadata - If not None, must be a dictionary of metadata to apply to the
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33 uploaded file and thumbnail.
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34 new_size - If not None, the image will be resized to the dimensions
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35 specified by new_size, which must be a (width, height) tuple.
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36 thumb_size - If not None, a thumbnail image will be created with the
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37 dimensions specified by thumb_size, which must be a (width,
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38 height) tuple. The thumbnail will use the same metadata, if
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39 present, as the image. The thumbnail filename will be the
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40 same basename as the image with a 't' appended. The
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41 extension will be the same as the original image.
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42
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43 A tuple is returned: (image_url, thumb_url) where thumb_url will be None if
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44 a thumbnail was not requested.
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45 """
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46
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47 logger.info('Processing image file: {}'.format(fp.name))
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48
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49 # Trying to use PIL (or Pillow) on a Django UploadedFile is often
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50 # problematic because the file is often an in-memory file if it is under
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51 # a certain size. This complicates matters and many of the operations we try
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52 # to perform on it fail if this is the case. To get around these issues,
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53 # we make a copy of the file on the file system and operate on the copy.
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54 # First generate a unique name and temporary file path.
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55 unique_key = uuid.uuid4().hex
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56 ext = os.path.splitext(fp.name)[1]
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57 temp_name = os.path.join(tempfile.gettempdir(), unique_key + ext)
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58
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59 # Write the UploadedFile to a temporary file on disk
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60 with temp_open(temp_name, 'wb') as temp_file:
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61 for chunk in fp.chunks():
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62 temp_file.write(chunk)
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63 temp_file.close()
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64
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65 # Resize image if necessary
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66 if new_size:
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67 image = Image.open(temp_name)
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68 if image.size > new_size:
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69 logger.debug('Resizing from {} to {}'.format(image.size, new_size))
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70 image.thumbnail(new_size, Image.ANTIALIAS)
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71 image.save(temp_name)
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72
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73 # Create thumbnail if necessary
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74 thumb = None
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75 if thumb_size:
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76 logger.debug('Creating thumbnail {}'.format(thumb_size))
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77 image = Image.open(temp_name)
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78 image.thumbnail(thumb_size, Image.ANTIALIAS)
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79 thumb = BytesIO()
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80 image.save(thumb, format=image.format)
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81
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82 # Upload images to S3
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83 file_key = unique_key + ext
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84 logging.debug('Uploading image')
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85 image_url = bucket.upload_from_filename(file_key, temp_name, metadata)
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86
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87 thumb_url = None
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88 if thumb:
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89 logging.debug('Uploading thumbnail')
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90 thumb_key = '{}t{}'.format(unique_key, ext)
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91 thumb_url = bucket.upload_from_string(thumb_key,
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92 thumb.getvalue(),
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93 metadata)
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94
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95 logger.info('Completed processing image file: {}'.format(fp.name))
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96
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97 return (image_url, thumb_url)
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