Using MongoEngine2 in Python

Mongoengine Basic Usage Examples:

 fromMongoengineImport* fromDatetimeImportdatetime#Connection database: Test#Connect (' Test ') # connects to local test databaseConnect'Test', host='127.0.0.1', port=27017, Username='Test', password='Test')#Defining our Documents#define document USER,POST, corresponding set User,postclassUser (Document):#required is true, the initial value must be givenemail = Stringfield (required=True) first_name= Stringfield (max_length=50) last_name= Stringfield (max_length=50) Date= Datetimefield (Default=datetime.now (), required=True)#Embedded Documents,it doesn ' t has its own collection in the databaseclassComment (embeddeddocument): Content=Stringfield () name= Stringfield (max_length=120)classPost (Document): Title= Stringfield (max_length=120, required=True)#Referencefield equivalent to foreign keyAuthor =Referencefield (User) tags= ListField (Stringfield (max_length=30)) Comments=ListField (Embeddeddocumentfield (Comment))#Allow inheritanceMeta = {'allow_inheritance': True}classTextpost (Post): Content=Stringfield ()classImagepost (Post): Image_path=Stringfield ()classLinkpost (Post): Link_url=Stringfield ()#Dynamic Document Schemas:dynamicdocument documents work in the same-as document but any data/attributes set to Them'll also be savedclassPage (dynamicdocument): Title= Stringfield (max_length=200, required=True) date_modified= Datetimefield (Default=datetime.now ())

Add data

John = User (email='[email protected]', first_name='John', last_name='Tao'). Save () Ross= User (email='[email protected]') Ross.first_name='Ross'Ross.last_name='Lawley'ross.save () comment1= Comment (content='Good work!', name ='Lindentao') Comment2= Comment (content='Nice article!') Post0= Post (title ='post0', tags = ['Post_0_tag']) post0.comments=[Comment1,comment2]post0.save () Post1= Textpost (title='Fun with Mongoengine', author=John) Post1.content='Took A look at mongoengine today, looks pretty cool.'Post1.tags= ['MongoDB','Mongoengine']post1.save () post2= Linkpost (title='Mongoengine Documentation', author=Ross) Post2.link_url='http://docs.mongoengine.com/'Post2.tags= ['Mongoengine']post2.save ()#Create A new page and add tagspage = page (title='Using Mongoengine') Page.tags= ['MongoDB','Mongoengine']page.save ()

Three collections created: User,post,page

View data

#View Data forPostinchpost.objects:PrintPost.titlePrint '='*Len (post.title)ifisinstance (Post, textpost):Printpost.contentifisinstance (Post, linkpost):Print 'Link:', Post.link_url#get a reference Document object directly from a reference field forPostinchtextpost.objects:Printpost.contentPrintpost.author.email au=TextPost.objects.all (). First (). AuthorPrintAu.email#Querying by Tags forPostinchPost.objects (tags='MongoDB'):    PrintPost.title num_posts= Post.objects (tags='MongoDB'). Count ()Print 'Found%d posts with tag "MongoDB"'%num_posts#Multi-Criteria Query (Import Q Class)User.objects ((Q (country='UK') & Q (age__gte=18)) | Q (age__gte=20))   #Update documentRoss = user.objects (first_name ='Ross') ross.update (date=DateTime.Now ()) User.objects (first_name='John'). Update (set__email='[email protected]')//Add product picture information to Lorem lorempic= Goodspic (name='l2.jpg', path='/static/images/l2.jpg') Lorem= Goods.objects (id='575d38e336dc6a55d048f35f') Lorem.update_one (Push__pic=lorempic)#Delete a documentRoss.delete ()

Note

ORM Full Name "Object Relational Mapping", that is, object-relational mapping, is to map a row of the relational database to an object, that is, a class corresponding to a table, so that the code is simpler to write, do not directly manipulate the SQL statement.

Using MongoEngine2 in Python