sqlalchemy

This article refers to the http://firefish.blog.51cto.com/298258/112794/solutionProblem:This article uses the SQLAlchemy to write to the MySQL database using scrapy crawl data on Ubuntu. But write the database of Chinese all is garbled, on-line check a pass this thought is the database coding problem, toss a pass originally is this sqlalchemy problem. "There is no problem with Windows, and this issue remain

Tags: database table configuration file Python Classic SQLAlchemyTake a look at the mappings in the SQLAlchemy framework, there are three ways to map SQLAlchemy: traditional mapping (classic),Modern mapping (modern), custom mapping.Here, we'll just talk about the classic map and the modern map.Classic Mapping:As the name implies, it is similar to hibernate, to write a lot of configuration files, here is a s

Tags: using otherwise code process JSON instance value materialized viewRecently do flask project, need to increase the function of paging, online search for the tutorial are combined with SQLAlchemy, but I use is not sqlalchemy, swollen wood do it? Here's what I'm doing. First, the front-end 1. Pass the page number Front-end I use Ajax to submit forms, so in the front-end form to add page this item (hidden

# Boot filefromFlask_scriptImportManager,server fromFlask_migrateImportmigratecommand,migrate fromRbacImportCreate_app,dbapp=Create_app () Manager=Manager (APP) Migrate=Migrate (app,db) Manager.add_command ("Runserver", Server ()) Manager.add_command ("DB", Migratecommand)if __name__=='__main__': Manager.run ()# Startup file Startup Auto TriggerfromFlaskImportFlask fromConfig.settingImportBaseconfig#Import Flask-sqlalchemy fromFlask_sqlalchemyImportSq

,Primary_key=True)Name=Column(String(50),Nullable=False,Unique=True)Def__init__ (selfname=): self. Name = name def __repr__ (selfreturn "Director (%r % (self. Name) engine = create_engine ( Span class= "S1" > ' dbms://user:[emailprotected]/dbname ' ) Base.metadata.create_all (engine) inserting the numbersThe inserted movie and the Guide object can be used for each other:Session=Sessionmaker(Bind=Engine)Session=Session()M1=Movie("Star Trek",2009)M1.Director=Director("JJ Abrams")D2=

Suppose you already have a Session factory class: Session = sessionmaker(bind=some_engine) Then the life cycle of the session instance can be: Shortest mode-Create a new session per request, close when you're done@contextmanagerdef get_session_scope(): try: s = Session() yield s s.commit() except: s.rollback() finally: s.close() This model is not suitable for Web projects or the disadvantage is that it consumes too fast the connection pool (db pool). I

Copy Code code as follows: def sa_obj_to_dict (obj, Filtrate=none, Rename=none): """ SQLAlchemy object to Dict :p Aram filtrate: Filtered Fields : Type filtrate:list or tuple :p Aram Rename: Need to rename, renamed after filtering processing, key for the original object's property name, value is required to change the name : Type Rename:dict : rtype:dict """ If Isinstance (obj.__class__, Declarativemeta):# an

One: SQLAlchemy use1: Creation of entity classesThe entity classes in ORM are different from the generic Python class, where __tablename__= "" is used to indicate that the class corresponds to a table in the database, and then defines a series of member properties that use Column (data type) To map to a specific column in the table.First, create the database engine and get a base class from a static method: Declarative_base () creates a Basemodel clas

conditions1. SMS, mail send using thread2. The trigger must be performed in a state where the database transaction is complete.Three. SQLAlchemy type of monitoringSQLAlchemy is the database background Python interface we take. Its transaction triggering mechanism includesField change Trigger in 1.orm2.orm Object state Change Trigger3.session Change Trigger4. Connection pool events, connection eventsFour. Concrete implementation 1. Mode oneI started w

Tags: pythonTool Description: SQLAlchemy is an ORM framework in the Python programming language, built on top of the database API, using relational object mappings for database operations, in short: converting objects to SQL and then executing SQL using the data API and getting execution results.How to work: manipulate a database by defining a class, a table in a database, a row of data in a class object corresponding to a table, inserting data into a

(User.username,userdetails.last_login). Join (Userdetails, Userdetails.id==user.id) All ()#INNER JOINraw=session.query (User.username,userdetails.last_login). Outerjoin (userdetails, Userdetails.id==user.id) All ()#outer JOIN stands for left join, right joins the table in reverse (SQLAlchemy no rightjoin), small table left joins right table high efficiency Q1=session.query (user.id) Q2=session.query (userdetails.id) Raw=q1.union (Q2). All () fromSQLA

( "User_count")). Group_by (User.Name). All ()) print (Session.query (User.name,func.sum (User.id). Label ( "User_id_sum")). Group_by (User.Name). All ()) #子查询 stmt=session.query (Address.user_id,func.count ( "Address_count"). Group_by (address.user_id). Subquery () print (Session.query (user,stmt.c.address_count) outerjoin (stmt, user.id==stmt.c.user_id). order_by (User.ID). All ()) #exists print (Session.query (User). Filter (exists (). where ( address.user_id==user.id)) print (session

Tags: long character type let nbsp esx password boolean lang color# # # SQLAlchemy Common data types:1. Integer: Reshape, which is mapped to the int type in the database.2. Float: Floating-point type, mapped to a float type in the database. He occupies the 32-bit.3. Double: dual-precision floating-point type, which is mapped to a double type in the database and occupies 64 bits.4. String: variable character type that is mapped to a varchar type in the

# # # FOREIGN Key:Creating a foreign key with SQLAlchemy is straightforward. When you add a field from the table, specify which field of the table the foreign key of the field will be. The fields from the foreign key of the table must be consistent with the primary key field type of the parent table.The sample code is as follows:1 fromSQLAlchemyImportCreate_engine, Column, Integer, String, Text, ForeignKey2 3 fromSqlalchemy.ext.declarativeImportDecl

The role of 1.SQLAlchemyORM Object Relational Mapping technology2.SQLAlchemy InstallationPip Install SQLAlchemy3. Using the example#Import: fromSQLAlchemyImportColumn, String, Create_engine,foreignkey fromSqlalchemy.ormImportsessionmaker,relationship fromSqlalchemy.ext.declarativeImportDeclarative_base#to create a base class for an object:Base =declarative_base ()#Initialize the database connection (PostgreSQL defaults to use PSYCOPG2 driver, can be o

Tags: multi-table return self ACK AC nmake from--authThere are two tables, an author's table, a book table, a writer who writes multiple books, a book that can be written by multiple authors, and links them by adding a new relational table. #!/usr/bin/env python #-*-coding:utf-8-*-# author Aliex-hrg from sqlalchemy import Table, Column, Integer,string,dat E, ForeignKey from sqlalchemy.orm import relationship from sqlalchemy.ext.declarative import decl

. SQLAlchemy table Operations 1. One-to-many relationshipsDemand: User groups, with dba,ddd groups Users, users can belong to only one user group The two tables are as follows:Group table:User table:Create the two tables above:#!/usr/bin/env python#-*-coding:utf-8-*-#auth:pangguoping fromSqlalchemy.ext.declarativeImportDeclarative_base fromSQLAlchemyImportColumn, Integer, String, ForeignKey, UniqueConstraint, Index fromSqlalchem

SQLAlchemy database connection Pooling is deferred initialization, which means you call Create_engine (...) at the beginning. After you create the database pool is empty, you are behind through session.connection () or Engine.connect () to start creating the connection,Whenever you create a connection, you call Engine.pool.status () to see what state the database connection pool is in, and the following is a description of the output of the following

Label:From flaskImport FlaskFrom Flask.ext.sqlalchemyImport SQLAlchemyFrom Flask.ext.migrateImport Migrate, MigratecommandFrom Flask.ext.scriptImport ManagerApp = Flask (__name__)app.config[' Sqlalchemy_database_uri '] =' Sqlite:///test.db 'db = SQLAlchemy (APP)Migrate = Migrate (app, DB)Manager = Manager (APP)Manager.add_command (' DB ', Migratecommand)Class Post (db. Model):ID = db. Column (db. Integer,primary_key=True)Name = db. Column (db. String

Label:From:http://blog.sina.com.cn/s/blog_633277f90100kpvm.html It seems that the most difficult part of ORM is the query. In particular, the object-oriented query, learning SQLAlchemy today, found that SQLAlchemy's query syntax is so flexible, marvel at its powerful expressive ability, but also have a deeper understanding of python. Here's a look at some of the query statements I wrote:Python code:#简单查询#注意User是一个类对象, user_table is a table in the data