Support min image file size

constrainedfilefield/fields.py

@@ -107,7 +107,7 @@ def formfield(self, **kwargs):
         formfield = super(ConstrainedFileField, self).formfield(**kwargs)
         if self.js_checker:
             formfield.widget.attrs.update(
-                {'onchange': 'validateFileSize(this, %d);' % (self.max_upload_size,)})
+                {'onchange': 'validateFileSize(this, 0, %d);' % (self.max_upload_size,)})
         return formfield
 
     def deconstruct(self):
@@ -139,7 +139,7 @@ class ConstrainedImageField(models.ImageField):
     ----------
     content_types : list of str
         List containing allowed content_types. Example: ['application/pdf', 'image/jpeg']
-    max_upload_size : int
+    [min|max]_upload_size : int
         Maximum file size allowed for upload, in bytes
             1 MB - 1048576 B - 1024**2 B - 2**20 B
             2.5 MB - 2621440 B
@@ -163,28 +163,31 @@ class ConstrainedImageField(models.ImageField):
 
     """
 
-    description = _("A file field with constraints on size and/or type")
+    description = _("An image file field with constraints on size and/or type")
 
     def __init__(self, *args, **kwargs):
-        self.max_upload_size = kwargs.pop("max_upload_size", 0)
-        assert isinstance(self.max_upload_size, int) and self.max_upload_size >= 0
+        self.upload_size = {}
+        for boundary in ['min', 'max']:
+            self.upload_size[boundary] = kwargs.pop(boundary + "_upload_size", 0)
+            assert isinstance(self.upload_size[boundary], int) and self.upload_size[boundary] >= 0
         self.content_types = kwargs.pop("content_types", [])
         self.mime_lookup_length = kwargs.pop("mime_lookup_length", 4096)
         assert isinstance(self.mime_lookup_length, int) and self.mime_lookup_length >= 0
         self.js_checker = kwargs.pop("js_checker", False)
-        # TODO: min_upload_size
         # TODO: [min|max]_[height|width]
 
         super(ConstrainedImageField, self).__init__(*args, **kwargs)
 
     def clean(self, *args, **kwargs):
         data = super(ConstrainedImageField, self).clean(*args, **kwargs)
 
-        if self.max_upload_size and data.size > self.max_upload_size:
+        small = self.upload_size['min'] and data.size < self.upload_size['min']
+        large = self.upload_size['max'] and data.size > self.upload_size['max']
+        if small or large:
             # Ensure no one bypasses the js checker
             raise forms.ValidationError(
-                _('File size exceeds limit: %(current_size)s. Limit is %(max_size)s.') %
-                {'max_size': filesizeformat(self.max_upload_size),
+                _('File size ' + 'below' if small else 'exceeds' + ' limit: %(current_size)s. Limit is %(max_size)s.') %
+                {'size': filesizeformat(self.upload_size['min' if small else 'max']),
                  'current_size': filesizeformat(data.size)})
 
         if self.content_types:
@@ -230,13 +233,14 @@ def formfield(self, **kwargs):
         formfield = super(ConstrainedImageField, self).formfield(**kwargs)
         if self.js_checker:
             formfield.widget.attrs.update(
-                {'onchange': 'validateFileSize(this, %d);' % (self.max_upload_size,)})
+                {'onchange': 'validateFileSize(this, %d, %d);' % (self.upload_size['min'], self.upload_size['max'],)})
         return formfield
 
     def deconstruct(self):
         name, path, args, kwargs = super(ConstrainedImageField, self).deconstruct()
-        if self.max_upload_size:
-            kwargs["max_upload_size"] = self.max_upload_size
+        for boundary in ['min', 'max']:
+            if self.upload_size[boundary]:
+                kwargs[boundary + "_upload_size"] = self.upload_size[boundary]
         if self.content_types:
             kwargs["content_types"] = self.content_types
         if self.mime_lookup_length:

constrainedfilefield/static/constrainedfilefield/js/file_checker.js

@@ -1,7 +1,14 @@
-function validateFileSize(input, maxSize, message) {
-    message = message || "File size ({size}) exceeds limit ({limit})"
-    if (input.files[0].size > maxSize) {
-        alert(message.replace('{size}', input.files[0].size).replace('{limit}', maxSize));
+function validateFileSize(input, min, max, message) {
+    var size = input.files[0].size;
+    var small = size < min;
+    var large = size > max;
+    if (small || large) {
+        message = message || "File size ({size}) is too "
+        message += small ? "low" : "large";
+        message += ". Please upload a file of at "
+        message += small ? "least" : "most";
+        message += " {limit}."
+        alert(message.replace('{size}', input.files[0].size).replace('{limit}', small ? min : max));
         input.value = '';
     }
 }

constrainedfilefield/tests/models.py

@@ -1,6 +1,6 @@
 from django.db import models
 
-from constrainedfilefield.fields import ConstrainedFileField
+from constrainedfilefield.fields import ConstrainedFileField, ConstrainedImageField
 
 
 class TestModel(models.Model):
@@ -10,6 +10,13 @@ class TestModel(models.Model):
         upload_to='testfile',
         content_types=['image/png'],
         max_upload_size=10240)
+    the_image = ConstrainedImageField(
+        null=True,
+        blank=True,
+        upload_to='testfile',
+        content_types=['image/png'],
+        min_upload_size=1024,
+        max_upload_size=10240)
 
 
 class TestModelJs(models.Model):
@@ -20,13 +27,25 @@ class TestModelJs(models.Model):
         content_types=['image/png'],
         max_upload_size=10240,
         js_checker=True)
+    the_image = ConstrainedImageField(
+        null=True,
+        blank=True,
+        upload_to='testfile',
+        content_types=['image/png'],
+        min_upload_size=1024,
+        max_upload_size=10240,
+        js_checker=True)
 
 
 class TestModelNoValidate(models.Model):
     the_file = ConstrainedFileField(
         null=True,
         blank=True,
         upload_to='testfile')
+    the_image = ConstrainedImageField(
+        null=True,
+        blank=True,
+        upload_to='testfile')
 
 
 class TestContainer(models.Model):

constrainedfilefield/tests/tests/backend.py

@@ -19,12 +19,15 @@ def test_create_empty_instance(self):
 
     def test_create_instance_with_file(self):
         instance = TestModel.objects.create(
-            the_file=File(self._get_sample_file('image2k.png'), 'the_file.png')
+            the_file=File(self._get_sample_file('image2k.png'), 'the_file.png'),
+            the_image=File(self._get_sample_file('image2k.png'), 'the_image.png')
         )
 
         self._check_file_url(instance.the_file, 'the_file.png')
+        self._check_file_url(instance.the_image, 'the_image.png')
 
         instance.the_file.delete()
+        instance.the_image.delete()
         instance.delete()
 
     def test_form_ok(self):

setup.py

@@ -21,9 +21,13 @@
 # allow setup.py to be run from any path
 os.chdir(os.path.normpath(os.path.join(os.path.abspath(__file__), os.pardir)))
 
+IMAGE_REQUIRE = [
+    'Pillow >= 4.0.0'
+]
+
 TESTS_REQUIRE = [
     'python-magic >= 0.4.2',
-]
+] + IMAGE_REQUIRE
 
 setup(
     name='django-constrainedfilefield',
@@ -49,6 +53,7 @@
     extras_require={
         'filetype': TESTS_REQUIRE,
         'coverage': TESTS_REQUIRE,
+        'image': IMAGE_REQUIRE,
     },
     keywords='django filefield validation file',
     classifiers=[