DetailForm: Use Meta class instead

Instead of class attributes, make a generic reusable the
FormOption class and update the DetailForm to use a Meta
class for options.

Signed-off-by: Roberto Rosario <Roberto.Rosario@mayan-edms.com>

mayan/apps/common/forms.py

@@ -4,6 +4,7 @@ import os
 
 from django import forms
 from django.conf import settings
+from django.contrib.admin.utils import label_for_field
 from django.core.exceptions import ImproperlyConfigured
 from django.db import models
 from django.utils.module_loading import import_string
@@ -13,7 +14,7 @@ from mayan.apps.acls.models import AccessControlList
 
 from .classes import Package
 from .models import UserLocaleProfile
-from .utils import resolve_attribute
+from .utils import introspect_attribute, resolve_attribute
 from .widgets import DisableableSelectWidget, PlainWidget, TextAreaDiv
 
 
@@ -41,26 +42,89 @@ class ChoiceForm(forms.Form):
     selection = forms.MultipleChoiceField(widget=DisableableSelectWidget())
 
 
+class FormOptions(object):
+    def __init__(self, form, kwargs, options=None):
+        """
+        Option definitions will be iterated. The option value will be
+        determined in the following order: as passed via keyword
+        arguments during form intialization, as form get_... method or
+        finally as static Meta options. This is to allow a form with
+        Meta options or method to be overrided at initialization
+        and increase the usability of a single class.
+        """
+        for option_definition in self.option_definitions:
+            name = option_definition.keys()[0]
+            default_value = option_definition.values()[0]
+
+            try:
+                # Check for a runtime value via kwargs
+                value = kwargs.pop(name)
+            except KeyError:
+                try:
+                    # Check if there is a get_... method
+                    value = getattr(self, 'get_{}'.format(name))()
+                except AttributeError:
+                    try:
+                        # Check the meta class options
+                        value = getattr(options, name)
+                    except AttributeError:
+                        value = default_value
+
+            setattr(self, name, value)
+
+
+class DetailFormOption(FormOptions):
+    # Dictionary list of option names and default values
+    option_definitions = (
+        {'extra_fields': []},
+    )
+
+
 class DetailForm(forms.ModelForm):
     def __init__(self, *args, **kwargs):
-        self.extra_fields = kwargs.pop('extra_fields', ())
+        self.opts = DetailFormOption(
+            form=self, kwargs=kwargs, options=getattr(self, 'Meta', None)
+        )
         super(DetailForm, self).__init__(*args, **kwargs)
 
-        for extra_field in self.extra_fields:
-            result = resolve_attribute(obj=self.instance, attribute=extra_field['field'])
-            label = 'label' in extra_field and extra_field['label'] or None
+        for extra_field in self.opts.extra_fields:
+            obj = extra_field.get('object', self.instance)
+            field = extra_field['field']
+
+            result = resolve_attribute(
+                attribute=field, obj=obj
+            )
+
+            label = extra_field.get('label', None)
+
+            if not label:
+                attribute_name, obj = introspect_attribute(
+                    attribute_name=field, obj=obj
+                )
+
+                if not obj:
+                    label = _('None')
+                else:
+                    try:
+                        label = getattr(
+                            getattr(obj, attribute_name), 'short_description'
+                        )
+                    except AttributeError:
+                        label = label_for_field(
+                            name=attribute_name, model=obj
+                        )
+
             # TODO: Add others result types <=> Field types
             if isinstance(result, models.query.QuerySet):
-                self.fields[extra_field['field']] = \
-                    forms.ModelMultipleChoiceField(
-                        queryset=result, label=label)
+                self.fields[field] = forms.ModelMultipleChoiceField(
+                    queryset=result, label=label
+                )
             else:
-                self.fields[extra_field['field']] = forms.CharField(
-                    label=extra_field['label'],
+                self.fields[field] = forms.CharField(
                     initial=resolve_attribute(
-                        obj=self.instance,
-                        attribute=extra_field['field']
-                    ),
+                        obj=obj,
+                        attribute=field
+                    ), label=label,
                     widget=extra_field.get('widget', PlainWidget)
                 )
 
@@ -131,7 +195,7 @@ class FileDisplayForm(forms.Form):
                 self.fields['text'].initial = file_object.read()
 
 
-class FilteredSelectionFormOptions(object):
+class FilteredSelectionFormOptions(FormOptions):
     # Dictionary list of option names and default values
     option_definitions = (
         {'allow_multiple': False},
@@ -147,35 +211,6 @@ class FilteredSelectionFormOptions(object):
         {'widget_attributes': {'size': '10'}},
     )
 
-    def __init__(self, form, kwargs, options=None):
-        """
-        Option definitions will be iterated. The option value will be
-        determined in the following order: as passed via keyword
-        arguments during form intialization, as form get_... method or
-        finally as static Meta options. This is to allow a form with
-        Meta options or method to be overrided at initialization
-        and increase the usability of a single class.
-        """
-        for option_definition in self.option_definitions:
-            name = option_definition.keys()[0]
-            default_value = option_definition.values()[0]
-
-            try:
-                # Check for a runtime value via kwargs
-                value = kwargs.pop(name)
-            except KeyError:
-                try:
-                    # Check if there is a get_... method
-                    value = getattr(self, 'get_{}'.format(name))()
-                except AttributeError:
-                    try:
-                        # Check the meta class options
-                        value = getattr(options, name)
-                    except AttributeError:
-                        value = default_value
-
-            setattr(self, name, value)
-
 
 class FilteredSelectionForm(forms.Form):
     """

mayan/apps/common/utils.py

@@ -6,6 +6,7 @@ import shutil
 import tempfile
 
 from django.conf import settings
+from django.core.exceptions import FieldDoesNotExist
 from django.db.models.constants import LOOKUP_SEP
 from django.urls import resolve as django_resolve
 from django.urls.base import get_script_prefix
@@ -142,6 +143,30 @@ def get_storage_subclass(dotted_path):
     return StorageSubclass
 
 
+def introspect_attribute(attribute_name, obj):
+    try:
+        # Try as a related field
+        obj._meta.get_field(field_name=attribute_name)
+    except (AttributeError, FieldDoesNotExist):
+        attribute_name = attribute_name.replace('__', '.')
+
+        try:
+            # If there are separators in the attribute name, traverse them
+            # to the final attribute
+            attribute_part, attribute_remaining = attribute_name.split(
+                '.', 1
+            )
+        except ValueError:
+            return attribute_name, obj
+        else:
+            return introspect_attribute(
+                attribute_name=attribute_part,
+                obj=related_field.related_model,
+            )
+    else:
+        return attribute_name, obj
+
+
 def TemporaryFile(*args, **kwargs):
     kwargs.update({'dir': setting_temporary_directory.value})
     return tempfile.TemporaryFile(*args, **kwargs)