Entity mapping using the Fluent API "Code-first series"

Now, let's learn how to configure entities using the Fluent API.

One. Configuring the Default data table schema

Student entity

usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingSystem.Text;usingSystem.Threading.Tasks;namespaceef4{ Public classStudent { Public intStudentID {Get;Set; }  Public stringStudentname {Get;Set; }  Public intStuaentage {Get;Set; }  Public stringStudentemail {Get;Set; }  PublicStandard Standard {Get;Set; } }}

Standard entity

usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingSystem.Text;usingSystem.Threading.Tasks;namespaceef4{ Public classStandard { Public intStandardid {Get;Set; }  Public intStandardName {Get;Set; }  PublicIcollection<student> Students {Get;Set; } }}

Context class:

usingSystem;usingSystem.Collections.Generic;usingSystem.Data.Entity;usingSystem.Linq;usingSystem.Text;usingSystem.Threading.Tasks;namespaceef4{ Public classDbcontextclass:dbcontext { PublicDbcontextclass ():Base("ConnectionStrings") { }        PublicDbset<student> Students {Get;Set; }  PublicDbset<standard> Standards {Get;Set; } protected Override voidonmodelcreating (Dbmodelbuilder modelBuilder) { Modelbuilder.hasdefaultschema (  "hello");            Base.       Onmodelcreating (ModelBuilder); }    }}

And then the resulting data table schema is the "Hello" we configured.

Of course, you can also set the schema for each table separately.

Two. Mapping entities to tables

usingSystem;usingSystem.Collections.Generic;usingSystem.Data.Entity;usingSystem.Linq;usingSystem.Text;usingSystem.Threading.Tasks;namespaceef4{ Public classDbcontextclass:dbcontext { PublicDbcontextclass ():Base("ConnectionStrings") { }        PublicDbset<student> Students {Get;Set; }  PublicDbset<standard> Standards {Get;Set; } protected Override voidonmodelcreating (Dbmodelbuilder modelBuilder) {//schema of the Configuration data table//modelbuilder.hasdefaultschema ("Hello"); //mapping entities to tables         modelbuilder.entity<student> ().           ToTable ("wahhaha"); Modelbuilder.entity<Standard> (). ToTable ("standardinfo","xxx");            Base.       Onmodelcreating (ModelBuilder); }    }}

Then the database is like this:

Open a table one at a glance:

Three. Splits an entity into multiple tables.

The following code splits a student entity into two tables.

usingSystem;usingSystem.Collections.Generic;usingSystem.Data.Entity;usingSystem.Linq;usingSystem.Text;usingSystem.Threading.Tasks;namespaceef4{ Public classDbcontextclass:dbcontext { PublicDbcontextclass ():Base("ConnectionStrings") { }        PublicDbset<student> Students {Get;Set; }  PublicDbset<standard> Standards {Get;Set; } protected Override voidonmodelcreating (Dbmodelbuilder modelBuilder) {//schema of the Configuration data table//modelbuilder.hasdefaultschema ("Hello"); //mapping entities to tables//modelbuilder.entity<student> ().           ToTable ("Wahhaha"); //modelbuilder.entity<standard> ().           ToTable ("Standardinfo", "xxx"); //Map an entity to multiple tablesModelbuilder.entity<student>(). Map (M={m.properties (P=P.studentid); M.properties (P=p.studentname); M.totable ("Studentinfo"); }). Map (M={m.properties (P=P.studentid); M.properties (P=p.stuaentage); M.properties (P=p.studentemail); M.totable ("studentdetails");           }); Modelbuilder.entity<Standard> (). ToTable ("Standardinfo"); Base.       Onmodelcreating (ModelBuilder); }    }}

The generated amount database is:

In the above code, we will student entities, split into two tables, Studentinfo and Studentdetail.

Map method need the delegate method as a parameter. You can pass the Action delegate or lambda expression in Map method, as shown below.

The map method requires a delegate as a parameter. You can pass an action delegate or lambda expression in this map method.

Entity mapping using the Fluent API "Code-first series"