EntityFrameworkDemoGS1

First install or update entity framework CLI from here. EF Core tools reference (.NET CLI) - EF Core | Microsoft Learn
Now create webapi project in VS.
Install two nuget packages from package manager
- EntityFrameworkCore.SqlServer
- If you are using Visual Studio then: EntityFrameworkCore.Tools
- If using VS Code or other text editor then: EntityFrameworkCore.Design
Now create ApplicationDbContext class and inherit from DbContext. Then hit ctrl+. to first add the using statement, then again hit same buttons for implement constructor from popup options.
Now we need to add SQL server connection string into appsettings.development.json then add it into Program.cs** with builder services appsettings.development.json

  "ConnectionStrings": {
    "DefaultConnection": "Server=localhost,1433;Database=EFCoreDemoGS1;User Id=sa;Password=sql@123;TrustServerCertificate=True;"
  }

Program.cs

builder.Services.AddDbContext<ApplicationDbContext>(options => options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection"))
    );

Now create a Genre.cs class with Id and Name property, and add DbSet Property into ApplicationDbContext.cs class.
Now add migration, if you are in vs code or Visual studio then command will be different for both. For Visual Studio

Add-Migration Initial
Update-Database

For VS Code

dotnet ef migrations add Initial
dotnet ef database update

In entity framework core, there are three-way to making configuration (Means, 3 way to tell EF about DB table configuration). Out of 3, fluent API one is most power one because it has maximum options.
- By Convention, like Id attribute will be set as the primary key of the table
- By Data Annotation, like [Key] is telling db that below's attribute is the db key or primary key.
- By fluent API in the ApplicationDbContext.
```
 protected override void OnModelCreating(ModelBuilder modelBuilder)
 {
     base.OnModelCreating(modelBuilder);
 
     modelBuilder.Entity<Genre>().HasKey(k=> k.Id);
 }
```

Set convention for all string in Program.cs

 protected override void ConfigureConventions(ModelConfigurationBuilder configurationBuilder)
 {
     configurationBuilder.Properties<string>().HaveMaxLength(150);
 }

If we need to change this for specific property then we can just add it OnModelCreating method.
```
 modelBuilder.Entity<Comment>().Property(c => c.Content).HasMaxLength(500);
```
These configurations inside OnModelCreating can grow very long so we'll shift them into separate config file inside Entities>Configurations
In every config file, implement IEntityTypeConfiguration interface with their individual type.

After separating all the configuration, add this line inside OnModelCreating

 modelBuilder.ApplyConfigurationsFromAssembly(Assembly.GetExecutingAssembly());

Now we'll add relation between our entities, like below. We added MovieId and Movie navigation property in comment to establish relation between them.

     public class Comment
     {
         public int Id { get; set; }
         public string? Content { get; set; }
         public bool Recommend { get; set; }
         public int MovieId { get; set; }
         public Movie Movie { get; set; } = null!;
     }

Ignore circular reference error of json serializer

Change this line in Program.cs

//change this into belows code
//builder.Services.AddControllers();
builder.Services.AddControllers()
    .AddJsonOptions(options => options.JsonSerializerOptions.ReferenceHandler = ReferenceHandler.IgnoreCycles);

Connected and disconnected model update

    //connected model because genre first loaded by context and same model will be updated
    [HttpPut("{id:int}/update")]
    public async Task<ActionResult<Actor>> Put(int id)
    {
        var genre = await context.Genres.FirstOrDefaultAsync(a => a.Id == id);

        if (genre is null)
        {
            return NotFound();
        }
        genre.Name += "2";
        await context.SaveChangesAsync();
        return Ok(genre);
    }

    //disconnected model because genre not loaded from context model
    [HttpPut("{id:int}/update2")]
    public async Task<ActionResult<Actor>> Put(int id, GenreCreationDTO genreDto)
    {
        var genre = mapper.Map<Genre>(genreDto);

        genre.Id = id;
        context.Update(genre);
        await context.SaveChangesAsync();
        return Ok(genre);
    }

Delete in two ways

    [HttpDelete("{id:int}/newway")]
    public async Task<ActionResult> Delete(int id)
    {
        var deletedRows = await context.Genres.Where(g => g.Id == id).ExecuteDeleteAsync();
        if (deletedRows == 0)
        {
            return NotFound();
        }

        return NoContent();
    }

    [HttpDelete("{id:int}/oldway")]
    public async Task<ActionResult> DeleteOldWay(int id)
    {
        var genre = await context.Genres.FirstOrDefaultAsync(g => g.Id == id);
        if (genre is null)
        {
            return NotFound();
        }

        context.Remove(genre);
        await context.SaveChangesAsync();

        return NoContent();
    }

link

iimamul / EntityFrameworkDemoGS1

EntityFrameworkDemoGS1

Ignore circular reference error of json serializer

Connected and disconnected model update

Delete in two ways

About

Languages