Added basic querying - find and find_one

mongomap/base.py

@@ -44,7 +44,7 @@ class BaseField(object):
             try:
                 value = self._to_python(value)
                 self._validate(value)
-            except ValueError:
+            except (ValueError, AttributeError):
                 raise ValidationError('Invalid value for field of type "' +
                                       self.__class__.__name__ + '"')
         elif self.required:
@@ -145,7 +145,7 @@ class TopLevelDocumentMetaclass(DocumentMetaclass):
         # Set up collection manager, needs the class to have fields so use
         # DocumentMetaclass before instantiating CollectionManager object
         new_class = super_new(cls, name, bases, attrs)
-        setattr(new_class, 'collection', CollectionManager(new_class))
+        new_class.objects = CollectionManager(new_class)
 
         return new_class
 
@@ -204,3 +204,11 @@ class BaseDocument(object):
             if value is not None:
                 data[field_name] = field._to_mongo(value)
         return data
+    
+    @classmethod
+    def _from_son(cls, son):
+        """Create an instance of a Document (subclass) from a PyMongo SOM.
+        """
+        data = dict((str(key), value) for key, value in son.items())
+        return cls(**data)
+

mongomap/collection.py

@@ -1,5 +1,29 @@
 from connection import _get_db
 
+
+class QuerySet(object):
+    """A set of results returned from a query. Wraps a MongoDB cursor, 
+    providing Document objects as the results.
+    """
+    
+    def __init__(self, document, cursor):
+        self._document = document
+        self._cursor = cursor
+       
+    def next(self):
+        """Wrap the result in a Document object.
+        """
+        return self._document._from_son(self._cursor.next())
+
+    def count(self):
+        """Count the selected elements in the query.
+        """
+        return self._cursor.count()
+
+    def __iter__(self):
+        return self
+
+
 class CollectionManager(object):
     
     def __init__(self, document):
@@ -14,4 +38,15 @@ class CollectionManager(object):
     def _save_document(self, document):
         """Save the provided document to the collection.
         """
-        _id = self._collection.save(document)
+        _id = self._collection.save(document._to_mongo())
+        document._id = _id
+
+    def find(self, query=None):
+        """Query the collection for document matching the provided query.
+        """
+        return QuerySet(self._document, self._collection.find(query))
+
+    def find_one(self, query=None):
+        """Query the collection for document matching the provided query.
+        """
+        return self._document._from_son(self._collection.find_one(query))

mongomap/document.py

@@ -14,4 +14,7 @@ class Document(BaseDocument):
     __metaclass__ = TopLevelDocumentMetaclass
 
     def save(self):
-        self.collection._save_document(self._to_mongo())
+        """Save the document to the database. If the document already exists,
+        it will be updated, otherwise it will be created.
+        """
+        self.objects._save_document(self)

mongomap/fields.py

@@ -59,6 +59,8 @@ class EmbeddedDocumentField(BaseField):
         super(EmbeddedDocumentField, self).__init__(**kwargs)
     
     def _to_python(self, value):
+        if not isinstance(value, self.document):
+            return self.document._from_son(value)
         return value
 
     def _to_mongo(self, value):
@@ -68,6 +70,7 @@ class EmbeddedDocumentField(BaseField):
         """Make sure that the document instance is an instance of the 
         EmbeddedDocument subclass provided when the document was defined.
         """
+        # Using isinstance also works for subclasses of self.document
         if not isinstance(value, self.document):
             raise ValidationError('Invalid embedded document instance '
                                   'provided to an EmbeddedDocumentField')