admin(major): add YAMLField for attributes, add codemirror editor

passbook/admin/fields.py

@@ -0,0 +1,61 @@
+"""YAML fields"""
+import yaml
+from django import forms
+from django.utils.translation import gettext_lazy as _
+
+
+class InvalidYAMLInput(str):
+    """Invalid YAML String type"""
+
+
+class YAMLString(str):
+    """YAML String type"""
+
+
+class YAMLField(forms.CharField):
+    """Django's JSON Field converted to YAML"""
+
+    default_error_messages = {
+        'invalid': _("'%(value)s' value must be valid YAML."),
+    }
+    widget = forms.Textarea
+
+    def to_python(self, value):
+        if self.disabled:
+            return value
+        if value in self.empty_values:
+            return None
+        if isinstance(value, (list, dict, int, float, YAMLString)):
+            return value
+        try:
+            converted = yaml.safe_load(value)
+        except yaml.YAMLError:
+            raise forms.ValidationError(
+                self.error_messages['invalid'],
+                code='invalid',
+                params={'value': value},
+            )
+        if isinstance(converted, str):
+            return YAMLString(converted)
+        return converted
+
+    def bound_data(self, data, initial):
+        if self.disabled:
+            return initial
+        try:
+            return yaml.safe_load(data)
+        except yaml.YAMLError:
+            return InvalidYAMLInput(data)
+
+    def prepare_value(self, value):
+        if isinstance(value, InvalidYAMLInput):
+            return value
+        return yaml.dump(value, explicit_start=True)
+
+    def has_changed(self, initial, data):
+        if super().has_changed(initial, data):
+            return True
+        # For purposes of seeing whether something has changed, True isn't the
+        # same as 1 and the order of keys doesn't matter.
+        data = self.to_python(data)
+        return yaml.dump(initial, sort_keys=True) != yaml.dump(data, sort_keys=True)