Question

我正在尝试创建一个可以从Sql Server DB检索信息的简单RESTful API。我使用.Net Core和EF Core for ORM。

我已经通过外键在我的数据库中映射了两个表。但是，当我尝试在EF核心中实现关系时，似乎BaseStats表中不存在引用Champions表中给定冠军行的行。

在进行API调用时，我得到以下结果：

{
"championId": 1,
"championName": "Vladimir",
"baseStats": null
 }

似乎EF核心在某种程度上无法识别这种关系。我一定错过了什么。

任何建议都将不胜感激:)以下是我的代码。提前谢谢。

主要实体：

public class Champion
{
    public int ChampionId                  { get; set; }
    public string ChampionName             { get; set; }

    public ICollection<BaseStat> BaseStats { get; set; }
}

依赖实体

public class BaseStat
{
    public int      BaseStatId { get; set; }
    public int      StatTypeId { get; set; }
    public decimal  Base       { get; set; }
    public decimal  Growth     { get; set; }

    public Champion Champion   { get; set; }
}

数据库上下文

public class Context : DbContext
{
    public DbSet<Champion>  Champions { get; set; }
    public DbSet<BaseStat>  BaseStats { get; set; }

    public Context(DbContextOptions<Context> options) : base (options)
    {
        //
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<BaseStat>()
            .HasOne(p => p.Champion)
            .WithMany(b => b.BaseStats);
    }

}

控制器

[Route("api/[controller]/[action]")]
public class ChampionController : Controller
{

    private readonly Context _context;

    public ChampionController(Context context)
    {
        _context = context; 
    }

    public async Task<JsonResult> Stats()
    {
        var champ = await _context.Champions.FirstOrDefaultAsync(c => c.ChampionId == 1);
        return Json(champ);
    }

}

Answer 1

我根据Ivan Stoev的回答更新了控制器中的统计数据操作。

public async Task<JsonResult> Stats()
{
Champion champion = await _context.Champions
    .Include(c => c.BaseStats)
    .FirstOrDefaultAsync();
    return Json(champion);
}

当动作返回正确的信息时，当我通过浏览器进行API调用时，它似乎继续加载，好像呼叫没有结束。（浏览器标签中的微调器，谷歌浏览器）

与此同时，我无法在Postman中进行API调用，而不会出现以下错误：

Could not get any response
There was an error connecting to http://localhost:50185/api/champion/stats.
Why this might have happened:
The server couldn't send a response:
Ensure that the backend is working properly
Self-signed SSL certificates are being blocked:
Fix this by turning off 'SSL certificate verification' in Settings > General
Client certificates are required for this server:
Fix this by adding client certificates in Settings > Certificates
Request timeout:
Change request timeout in Settings > General

有没有人知道可能导致这种情况的原因？

EF Core与Sql Server的一对多关系不起作用

1 个答案: