Add ModelAttribute helper class to document the attributes of a document available for user interaction

mayan/apps/common/classes.py

@@ -0,0 +1,68 @@
+from django.db import models
+from django.utils.translation import ugettext
+
+
+class ModelAttribute(object):
+    __registry = {}
+
+    @classmethod
+    def get_for(cls, model, type_names=None):
+        result = []
+
+        try:
+            for type_name, attributes in cls.__registry[model].iteritems():
+                if not type_names or type_name in type_names:
+                    result.extend(attributes)
+
+            return result
+        except IndexError:
+            # We were passed a model instance, try again using the model of the
+            # instance
+
+            # If we are already in the model class, exit with an error
+            if model.__class__ == models.base.ModelBase:
+                raise
+
+            return cls.get_for[type(model)]
+
+    @classmethod
+    def get_choices_for(cls, model, type_names=None):
+        return [(attribute.name, attribute) for attribute in cls.get_for(model, type_names)]
+
+    @classmethod
+    def help_text_for(cls, model, type_names=None):
+        result = []
+        for count, attribute in enumerate(cls.get_for(model, type_names), 1):
+            result.append('{}) {}'.format(count, unicode(attribute.get_display(show_name=True))))
+
+        return ' '.join([ugettext('Available attributes: '), ', '.join(result)])
+
+    def get_display(self, show_name=False):
+        if self.description:
+            return u'{} - {}'.format(self.name if show_name else self.label, self.description)
+        else:
+            return unicode(self.name if show_name else self.label)
+
+    def __unicode__(self):
+        return self.get_display()
+
+    def __init__(self, model, name, label=None, description=None, type_name=None):
+        self.model = model
+        self.label = label
+        self.name = name
+        self.description = description
+
+        for field in model._meta.fields:
+            if field.name == name:
+                self.label = field.verbose_name
+                self.description = field.help_text
+
+        self.__registry.setdefault(model, {})
+
+        if isinstance(type_name, list):
+            for single_type in type_name:
+                self.__registry[model].setdefault(single_type, [])
+                self.__registry[model][single_type].append(self)
+        else:
+            self.__registry[model].setdefault(type_name, [])
+            self.__registry[model][type_name].append(self)