ORM -- query type, association query

  ORM In the frame , An alias will be set for the primary key in each model class ：pk

        models.Projects.objects.filter(id=2) Equivalent to models.Projects.objects.filter(pk=2)

1.filter() and exclude() Query type

        exclude() Namely filter() Reverse query of
        1.1 filter() Supported query types ：

                models. Model class name .objects.filter( Field name __ Query type =xxxx)

          Add ：

                filter(id__gt=2)

                filter(id__gte=2)

                filter(id__lt=2)

                filter(id__lte=2)

        1.2 exclude() Reverse query     

                filter() Methods support all query types             

2. Relational query

        When a foreign key is defined in a model class , When adding data to the table corresponding to this model class , You must also specify which data of the parent table to associate the new data from the table

        2.1 stay Interfaces Define foreign keys in the model class , relation Projects Model class

        2.2 transfer

                After the move ,Interfaces The table generated by the model class will automatically   Generate foreign keys : Foreign key name _id

         2.3 Foreign key Association creation

                The way 1:

                        2.3.1 First get the parent table model object , Only... Can be used here get(), Out-of-service filter(), why ？

                        2.3.2  Pass the obtained key field name other than the parent table model object as a parameter

                use postman View after request interfaces surface  

                

                 The way 2:

                        2.3.1 First get the parent table model object , Then get the parent table id value

                        2.3.2  Add parent table Primary key value With Foreign key name _id Pass... As a parameter

         2.4 Foreign key Association query

                2.4.1 Use to get parent table data from table data

                        utilize . The parent table model class name is lowercase   obtain

                        Get all the project information including the registered interface

                                Interfaces.objects.filter(name__contains=' Registered interface ').first().projects

                  2.4.2  Use the parent table data to obtain the data from the table

                        utilize From the table model, the class name is lowercase _set obtain ;

                         Or in the foreign key field of the slave table model , Appoint related_name='xxxx':

                        models.Projects.objects.filter(leader__contains='jeanet')[0].xxxx.all()                

                          Get the project leader=jeanet All interface information :

                         models.Projects.objects.filter(leader__contains='jeanet')[0].interfaces_set.all()      

                2.4.3 Relational query

                        2.4.3.1 Get the data from the parent table through the parent table parameters

                    From the table model class QuerySet object ( Associated attribute fields __ Field name in the parent table model class __ Query type = value ）

                        2.4.3.2 Get the parent table data from the table parameters

                         Of the parent table model class QuerySet object ( From table related_name Field name __ From the field name in the table model class __ Query type = value ）