Day6 --- Sqlalchemy advanced

Single table data query

stay model.py Create model class in file

from flask_sqlalchemy import SQLAlchemy  # Import 

db=SQLAlchemy()  # Instantiate database connection object 

# Create model classes 
class UserModel(db.Model):
    # primary_key Primary key  autoincrement Self increasing  default Default 
    id=db.Column(db.Integer,primary_key=True,autoincrement=True,comment='ID')
    name=db.Column(db.String(32),default='',comment=' name ')
    age=db.Column(db.Integer,default=0,comment=' Age ')
    balance=db.Column(db.DECIMAL(10,2),comment=' assets ') # DECIMAL floating-point 

Migrating data

 Initialize migration file 
python manage.py db init
 Generate migration file 
python manage.py db migrate
 Perform the migration 
python manage.py db upgrade
 Migration completed 

Realize the data addition and single table query of model classes in the blueprint

from flask import Blueprint  # Import blueprint 
from flask_restful import Api,Resource,fields,marshal
from models.model import UserModel, db
# # url_prefix #  Specify the prefix of all routes under the current blueprint 
user_dp=Blueprint('user_dp',__name__,url_prefix='/users') # Instantiate blueprint objects 
api=Api(user_dp)  # Instantiate the blueprint collector # Instantiate a Api object  Api Object is used to collect routes 
# Define class view   Inherited from Resource class , adopt Api To collect instantiated objects 
class UserView(Resource):
    def get(self):       # Test success 
    # Add data 
        u1=UserModel(
            name=' Sicong ',age=12,balance=100,
        )
        u2=UserModel(
            name=' The pony ',age=17,balance=100,
        )
        u3=UserModel(
            name=' Old horse ',age=19,balance=1030,
        )
        db.session.add_all([u1,u2,u3])
        db.session.commit()
        return 'ssss'

# Add route 
api.add_resource(UserView,'/user') # The full address is  /users/user

filter(), filter_by Implement filter query operation

class UserView(Resource):
    def get(self):       # Test success 
    	#lst=UserModel.query.all() # Query all 
        #filter(), filter_by Implement filtering operation   The two methods work the same 
        #lst=UserModel.query.filter(UserModel.name==' Old horse ').first() #filter() Implement filtering operation 
        lst=UserModel.query.filter_by(name=' Old horse ').first()  #filter_by Implement filtering operation 
        print(lst)

Paging and sorting

class UserView(Resource):
    def get(self):       # Test success 
    	# Pagination   Sort   data 
        #  first page  0,2 # the number of pages -1 *  Number of entries per page 
        #  The second page  2,2
        #  The third page  4,2
        # page=2
        # page_size=2
        ##  Skip the second query , Limit output 2 strip 
        # UserModel.query.offset(offset).limit(page_size).all()
        ##  Sort 
        ## (1). Sort by age in ascending order ,  Default ascending order ,  It can be omitted ".asc()"
        # UserModel.query.order_by(UserModel.age.asc()).all()
        # (2). Sort by age 
        UserModel.query.order_by(UserModel.age.desc()).all()

Logical operations

class UserView(Resource):
    def get(self):       # Test success 
    	from sqlalchemy import or_,and_,not_ # Guide pack 
        ## Logical operations 
        lst=UserModel.query.filter(or_(UserModel.name==' Old horse ',UserModel.name==' The pony ')).all() # or 
        lst=UserModel.query.filter(and_(UserModel.name==' Old horse ',UserModel.age==19)).all()   # And 
        lst=UserModel.query.filter(not_(UserModel.name==' Old horse ')).all()     # Not 
        print(lst)

Comparison query

class UserView(Resource):
    def get(self):       # Test success 
    	##  Comparison query 
        lst=UserModel.query.filter(UserModel.age.__lt__(18)).all() # Less than 
        lst=UserModel.query.filter(UserModel.age.__le__(18)).all() # Less than or equal to 
        lst=UserModel.query.filter(UserModel.age.__gt__(18)).all() # Greater than 
        lst=UserModel.query.filter(UserModel.age.__ge__(18)).all() # Greater than or equal to 
        print(lst)

in Inquire about TODO in operation

class UserView(Resource):
    def get(self):       # Test success 
    	# in Inquire about TODO in  operation 
        lst=UserModel.query.filter(UserModel.name.in_((' The pony ',))).all() # It must be in the form of Yuanzu or list 
        return marshal(lst,{
    
            'id':fields.Integer,
            'name':fields.String,
            'age':fields.Integer,
            'balance':fields.Float
        })

# Aggregate query

class UserView(Resource):
    def get(self):       # Test success 
    	from sqlalchemy import func  # Guide pack 
        # Aggregate query 
        lst=db.session.query(func.count(UserModel.id)).first()[0] # Count the number of data rows 
        lst=db.session.query(func.sum(UserModel.age)).first()[0] # Sum of Statistics 
        lst=db.session.query(func.avg(UserModel.age)).first()[0] # Statistical data please mean 
        print(lst)

Relationship query One-to-many relation

The establishment of a one to many relationship : One party establishes a relationship , Establish foreign keys by multiple parties
Create two tables The primary table is bound to the secondary table
stay model.py Create model class in file
Migrate after creation

from flask_sqlalchemy import SQLAlchemy  # Import 

db=SQLAlchemy()  # Instantiate database connection object 
#  Professional model   One to many model creation 
class Sub(db.Model):
    id=db.Column(db.Integer,primary_key=True,autoincrement=True,comment=' major ID')
    name=db.Column(db.String(32),comment=' Major name ')
    stu=db.relationship('Stu',backref='sub')  # Declare a relationship with that model , There will be no substantive operations in the database 

#  Student model 
class Stu(db.Model):
    id=db.Column(db.Integer,primary_key=True,autoincrement=True,comment=' Student ID')
    name=db.Column(db.String(32),comment=' Student name ')
    age=db.Column(db.Integer,comment=' Student age ')
    sub_id=db.Column(db.Integer,db.ForeignKey('sub.id')) # Declare a field , And the field is foreign key , Foreign keys are associated with that table 

The blueprint realizes adding and querying data

from flask import Blueprint  # Import blueprint 
from flask_restful import Api,Resource,fields,marshal
from models.model import UserModel, db, Sub, Stu

# # url_prefix #  Specify the prefix of all routes under the current blueprint 
user_dp=Blueprint('user_dp',__name__,url_prefix='/users') # Instantiate blueprint objects 

api=Api(user_dp)  # Instantiate the blueprint collector # Instantiate a Api object  Api Object is used to collect routes 

# Define class view   Inherited from Resource class , adopt Api To collect instantiated objects 
class UserView(Resource):
    def get(self):       # Test success 
    	s1=Sub(name=' Artificial intelligence ')
        s2=Sub(name=' Cutaway ')
        s3=Sub(name=' Copy of the ')
        stu1=Stu(name=' ha-ha ',age=18,sub=s1)
        stu2=Stu(name=' Hey ',age=12,sub=s2)
        stu3=Stu(name=' Hoho ',age=16,sub=s3)
        db.session.add_all([s1,s2,s3])
        db.session.add_all([stu1,stu2,stu3])
        db.session.commit()
        return 'sd'
# Add route 
api.add_resource(UserView,'/user') # The full address is  /users/user

. One to many queries
Is the query & Reverse query

class UserView(Resource):
    def get(self):       # Test success 
    	#  Is the query   One party inquires information from many parties 
        sub_info=Sub.query.filter(Sub.name==' Artificial intelligence ').first()
        print(sub_info.id)
        for i in sub_info.stu:     #  Traverse the bound data  
            print(i.name,i.age)

        #  Reverse query   Find out the information of one party from multiple parties 
        stu_info=Stu.query.filter(Stu.name==' ha-ha ').first()
        print(stu_info.name,stu_info.age,stu_info.sub_id)  # Display the queried data 
        print(stu_info.sub.name) # Print out the name of the binding foreign key 

Relationship query Many to many relationship

The establishment of many to many relationship

1.  First define two models that need to do many to many 
2.  Use Table Define an intermediate table , The intermediate table is generally the foreign key field containing two models , And let them both be one “ Composite primary key ”.
3.  Choose one of the two models that need to do many to many , Define a relationship attribute , To bind the relationship between the three , In the use of relationship When , Need to pass in a secondary= Middle table model name . 

stay model.py Create model classes in the file
Migrate after creation

# Create middle table 
article_tag=db.Table(
    'article_tag',
    db.Column('article_id',db.Integer,db.ForeignKey('article.id'),primary_key=True),
    db.Column('tag_id',db.Integer,db.ForeignKey('tag.id'),primary_key=True)
)

# Article table   Many to many relationship 
class Article(db.Model):
    id=db.Column(db.Integer,primary_key=True,autoincrement=True,comment='Id')
    title = db.Column(db.String(32), comment=' Article name ')
    # Indicate two tables 
    tags=db.relationship('Tag',secondary=article_tag,backref='articles')
# The label table 
class Tag(db.Model):
    id=db.Column(db.Integer,primary_key=True,autoincrement=True,comment='Id')
    name = db.Column(db.String(32), comment=' Tag name ')

The blueprint realizes the addition and query of data
Many to many add data

from flask import Blueprint  # Import blueprint 
from flask_restful import Api,Resource,fields,marshal
from models.model import UserModel, db, Sub, Stu, Article, Tag

# # url_prefix #  Specify the prefix of all routes under the current blueprint 
user_dp=Blueprint('user_dp',__name__,url_prefix='/users') # Instantiate blueprint objects 

api=Api(user_dp)  # Instantiate the blueprint collector # Instantiate a Api object  Api Object is used to collect routes 

# Define class view   Inherited from Resource class , adopt Api To collect instantiated objects 
class UserView(Resource):
    def get(self):       # Test success 
    	##  Many to many data add 
        t1=Tag(name='python')   # First add foreign key data   Add binding data 
        t2=Tag(name='java')

        # db.session.commit() # After adding, comment this   Then run the lower 
        # return ''

        a1=Article(title=' artificial ',tags=[t1])
        a2=Article(title=' data ',tags=[t2])
        a3=Article(title=' The whole stack ',tags=[t1,t2])
		# db.session.add_all([t1,t2])
        db.session.add_all([a1,a2,a3])
        db.session.commit()
# Add route 
api.add_resource(UserView,'/user') # The full address is  /users/user

Many to many queries

class UserView(Resource):
    def get(self):       # Test success 
    	# Many-to-many queries   Query all articles involved in a tag 
        tag_info=Tag.query.filter(Tag.name=='python').first()
        print(tag_info.name)
        print(tag_info.articles)
        for i in tag_info.articles:
            print(i.title)  # You can query the binding foreign key name 
		#  Query all the tags of the article 
        article_info=Article.query.filter(Article.id==2).first()
        print(article_info.title)
        print(article_info.tags)   #  View the data of the article table bound to itself 
        for i in article_info.tags:
            print(i.name)   # Query the other party's data