Python 3.x database framework Sqlalchemy for SQlite (continued)

Next, we will explain the Sqlalchemy framework. Here is another example.

Related reading: database framework of Python 3.x Sqlalchemy for SQlite operations

As follows:

This example is based on others' Code.

1. _ Author _ ='Minggxu9'
2. ImportSqlalchemy
3. FromSqlalchemyImportCreate_engine
4. Eng = create_engine ('Sqlite: //: memory :', Echo =True)
6. Eng.exe cute ("Select 1"). Scalar ()
8. FromSqlalchemy. ext. declarativeImportDeclarative_base
9. Base = declarative_base ()
11. ######################################## #################
12. FromSqlalchemyImportJoin, Table, MetaData ,\
13. Select, func ,\
14. And _,\
15. Column, ForeignKey ,\
16. Integer, String, Text, Binary
18. FromSqlalchemy. ormImportDeferred, mapper ,\
19. Relationship, column_property ,\
20. Object_session ,\
21. Validates
23. ######################################## #################
24. Metadata = MetaData ()
25. ######################################## #################
26. ClassBook (Base ):
27. _ Tablename __='Book'
28. Book_id = Column (Integer, primary_key =True)
29. Title = Column (String (200), Nullable =False)
30. Summary = Column (String (2000))
31. Excerpt = deferred (Column (Text ))
32. Photo1 = deferred (Column (Binary), group ='Photos')
33. Photo2 = deferred (Column (Binary), group ='Photos')
34. Photo3 = deferred (Column (Binary), group ='Photos')
36. ClassAddress (Base ):
37. _ Tablename __='Address'
38. Id = Column (Integer, primary_key =True)
39. User_id = Column (Integer, ForeignKey ('User. id'))
41. ClassUser (Base ):
42. _ Tablename __='User'
43. Id = Column (Integer, primary_key =True)
44. Firstname = Column (String (50))
45. Lastname = Column (String (50))
46. # Fullname = column_property (firstname + ''+ lastname)
47. # Address_count = column_property (
48. # Select ([func. count (Address. id)]). \
49. # Where (Address. user_id = id)
50. #)
51. Addresses = relationship ("Address") 
52.  
53. @ Validates('Address')
54. DefValidate_address (Self, Key, address ):
55. Assert '@' InAddress. email
56. ReturnAddress 
57.  
58. @ Property
59. DefFullname (Self):
60. Return Self. Firstname +''+Self. Lastname 
61.  
62. @ Property
63. DefAddress_count (Self):
64. ReturnObject_session (Self).\
65. Scalar (select ([func. count (Address. id)]). \
66. Where (Address. user_id =Self. Id ))
67. ######################################## #################
68. Base. metadata. create_all (eng)
70. # Ed1_user = User ('ed1', 'ed1 Jones ', 'ed1spassword ')
71. # Ed2_user = User ('ed2', 'ed2 Jones ', 'ed2spassword ')
73. # Print ("-----------------------")
75. # From sqlalchemy. orm import Session
76. # Ses = Session (bind = eng)
77. # Ses. add (ed1_user)
78. # Ses. add (ed2_user)
79. # Ses. commit ()