Open Project
Open the ASP.NET Core application in Visual Studio 2019.
Adding a controller API
Right-click the project, and then add a new file named Api folder. Then, right-click the folder, and select Add> New Scaffolded Item. Use Entity Framework API Controller with selection operations. Now select an existing model class, and then click Add.
View generated by the controller
Generating code comprising a new controller class. Top of the class is defined by two properties.
[Route("api/[controller]")]
[ApiController]public class GamesController : ControllerBase
A first specify the route for operation of the controller api / [controller], which means that if the controller named GamesController, the route of api / Games.
The second attribute [ApiController] validation added to some useful categories, such as to ensure that each action contains its own method [the Route] property.
public class GamesController : ControllerBase{ private readonly AppDbContext _context; public GamesController(AppDbContext context) {
_context = context;
}
The controller using the existing AppDbContext, and passed to its constructor. Each operation will use this field to the data processing application.
// GET: api/Games[HttpGet]public IEnumerable<Game> GetGame(){ return _context.Game;
}
第一种方法是使用[HttpGet]属性指定的简单GET请求。它不带任何参数，并返回数据库中所有game的列表。
// GET: api/Games/5[HttpGet("{id}")]public async Task<IActionResult> GetGame([FromRoute] int id){ if (!ModelState.IsValid)
{ return BadRequest(ModelState);
} var game = await _context.Game.FindAsync(id); if (game == null)
{ return NotFound();
} return Ok(game);
}
下一个方法指定路由中的{id}，它将被添加到/之后的路由中，因此完整的路由将类似于api/Games/5，如顶部的注释所示。该id输入被映射到方法上的id参数。在方法内部，如果模型无效，则返回一个BadRequest结果。下载VS 2019否则，EF将尝试查找与提供的id匹配的记录。如果找不到，将返回NotFound结果，否则将返回相应的game记录。
// PUT: api/Games/5
[HttpPut("{id}")]
public async Task<IActionResult> PutGame([FromRoute] int id, [FromBody] Game game)
{
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
if (id != game.Id)
{
return BadRequest();
}
_context.Entry(game).State = EntityState.Modified;
try
{
await _context.SaveChangesAsync();
}
catch (DbUpdateConcurrencyException)
{
if (!GameExists(id))
{
return NotFound();
}
else
{
throw;
}
}
return NoContent();
}
接下来，使用[HttpPut]对API的请求来执行更新。新Game记录在请求的正文中提供。执行一些验证和错误检查，如果一切顺利，数据库中的记录将使用请求体中提供的值进行更新。否则，将返回适当的错误响应。
// POST: api/Games
[HttpPost]
public async Task<IActionResult> PostGame([FromBody] Game game)
{
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
_context.Game.Add(game);
await _context.SaveChangesAsync();
return CreatedAtAction("GetGame", new { id = game.Id }, game);
}
一个[HttpPost]请求用于向系统添加新记录。与[HttpPut]一样，记录被添加到请求的正文中。如果有效，则EF Core将记录添加到数据库中，并且该操作将返回更新后的记录(带有数据库生成的ID)和一个指向API记录的链接。
// DELETE: api/Games/5
[HttpDelete("{id}")]
public async Task<IActionResult> DeleteGame([FromRoute] int id)
{
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
var game = await _context.Game.FindAsync(id);
if (game == null)
{
return NotFound();
}
_context.Game.Remove(game);
await _context.SaveChangesAsync();
return Ok(game);
}
最后，[HttpDelete]使用带有ID 的路由来删除记录。如果请求有效，并且存在具有给定ID的记录，那么EF Core从数据库中将其删除。
添加Swagger
Swagger是一个API文档和测试工具，可以作为一组服务和中间件添加到ASP.NET Core应用程序中。要做到这一点，请先右键单击该项目，然后选择Manage NuGet Packages。单击Browse，搜索Swashbuckle.AspNetCore并安装相应的软件包。
After installation, open Startup.cs and add the following to the end ConfigureServices method:
services.AddSwaggerGen(c =>
{
c.SwaggerDoc("v1", new Info { Title = "My API", Version = "v1" });
});
At the same time, also you need to add Swashbuckle.AspNetCore.Swagger in the top of the file.
Next, before UseMvc, add the following in the Configure method:
// Enable middleware to serve generated Swagger as a JSON endpoint.
app.UseSwagger();
// Enable middleware to serve swagger-ui (HTML, JS, CSS, etc.),
// specifying the Swagger JSON endpoint.
app.UseSwaggerUI(c =>
{
c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
});
Now you should be able to build and run the application.
In the browser, navigate to / swagger in the address bar, you should see a list of API endpoints and application model.
Click on an endpoint in the Games, in attempt to execute it, to see different endpoints.