Thumbnail field added

src/eplasty/field/__init__.py

@@ -3,4 +3,4 @@
 from eplasty.field.helper import *
 from eplasty.field.file import FileField
 from eplasty.field.adapter import *
-from eplasty.field.image import Image
+from eplasty.field.image import Image, Thumb

src/eplasty/field/base.py

@@ -16,6 +16,8 @@ class Field(object):
 
     def __init__(self, *args, **kwargs):
 #        self.kwargs = kwargs
+        # Dependent fields need to be erased when this field is set
+        self.dependent_fields = []
         if 'default' in kwargs:
             self._default = kwargs['default']
 
@@ -39,6 +41,8 @@ def __set__(self, inst, v):
         try:
             if self._is_compatible(v):
                 inst._current[self.name] = v
+                for field in self.dependent_fields:
+                    field.__set__(inst, None)
                 inst.touch()
             else:
                 raise TypeError('Type {0} is incompatible with field {1}'.format(

src/eplasty/field/blob.py

@@ -13,6 +13,7 @@ class Blob(Field):
 
     def __init__(self, mimetype=None):
         self.fixed_mimetype = mimetype
+        super(Blob, self).__init__()
 
     def bind_class(self, cls, name):
         namec = ft.partial(str.format, '{0}_{1}', name)
@@ -25,12 +26,6 @@ def bind_class(self, cls, name):
         super(Blob, self).bind_class(cls, name)
         return self
 
-    def __get__(self, inst, cls):
-        if inst and not inst._current.get(self.name):
-            return BlobData(None, self.fixed_mimetype, None)
-        else:
-            return super(Blob, self).__get__(inst, cls)
-
     def hydrate(self, inst, col_vals, dict_, session):
         if col_vals[self.blob_column.name] is None:
             dict_[self.name] = None
@@ -39,11 +34,12 @@ def hydrate(self, inst, col_vals, dict_, session):
                 mimetype = self.fixed_mimetype
             else:
                 mimetype = col_vals[self.mime_column.name]
-        dict_[self.name] = BlobData(
-            col_vals[self.blob_column.name].tobytes(),
-            mimetype,
-            col_vals[self.filename_column.name],
-        )
+            blob_data = col_vals[self.blob_column.name]
+            dict_[self.name] = BlobData(
+                blob_data and blob_data.tobytes(),
+                mimetype,
+                col_vals[self.filename_column.name],
+            )
 
     def get_c_vals(self, dict_):
         obj = dict_.get(self.name)

src/eplasty/field/image.py

@@ -13,7 +13,7 @@ def __init__(self, *args, **kwargs):
     def hydrate(self, inst, col_vals, dict_, session):
         super(Image, self).hydrate(inst, col_vals, dict_, session)
         blob = dict_.get(self.name)
-        if blob.data is not None:
+        if blob and blob.data is not None:
             dict_[self.name] = pystacia.read_blob(blob.data, self.img_format)
             dict_[self.name].filename =  blob.filename
         else:
@@ -31,4 +31,27 @@ def get_c_vals(self, dict_):
         return super(Image, self).get_c_vals(dict_)
 
     def _is_compatible(self, value):
-        return isinstance(value, pystacia.Image)
+        return value is None or isinstance(value, pystacia.Image)
+
+class Thumb(Image):
+    def __init__(self, *args, **kwargs):
+        origin = kwargs.pop('origin')
+        self.size = kwargs.pop('size')
+        origin.dependent_fields.append(self)
+        self.origin = origin
+        super(Thumb, self).__init__(*args, **kwargs)
+
+    def __get__(self, inst, cls):
+        result = super(Thumb, self).__get__(inst, cls)
+        if result is not None:
+            return result
+        img = self.origin.__get__(inst, cls)
+        if img is None:
+            return img
+        to_width, to_height = self.size
+        factor = min(to_width/img.width, to_height/img.height)
+        if factor < 1:
+            img = img.copy()
+            img.rescale(factor=factor)
+        self.__set__(inst, img)
+        return img

src/test/test_image.py

@@ -16,6 +16,8 @@ class Test(unittest.TestCase):
     def setUp(self):
         class Image(ep.Object):
             image = ep.f.Image()
+            thumb = ep.f.Thumb(origin=image, size=(100, 100))
+
         self.Image = Image
         self.conn = get_test_conn()
         ep.set_context(self.conn)
@@ -37,5 +39,6 @@ def test_read(self):
         ep.start_session()
         pythons = self.Image.get(1)
         img = pythons.image
+        thumb = pythons.thumb
         self.assertEqual(img.width, 640)
-
+        self.assertEqual(thumb.width, 100)