Question

使用.net core + angular 5，并尝试返回列表，但JSON响应中有一个字段 null 。使用Postman触发调试并在VS中看到该字段具有来自DB的值。不知道为什么它不在JSON响应中。

[HttpGet("[action]")]
public IEnumerable<HikingTrail> HikingTrails()
{
    var dbOptions = new DbContextOptionsBuilder<HikingTrailContext>();
            dbOptions.UseSqlServer("Server = (localdb)\\mssqllocaldb; Database = HikingApp");
    var dbContext = new DAO.HikingTrailContext(dbOptions.Options);
    return dbContext.HikingTrails.ToList();
}

返回：我对＆＃34; mountainRange ＆＃34;感兴趣字段不为空。在调试窗口中，它具有正确的值。

{ ＆＃34; url＆＃34;：null，＆＃34; hikingTrailId＆＃34;：159， ＆＃34; mountainRange ＆＃34;：null， ＆＃34; name＆＃34;：＆＃34;我的自定义名称＆＃34;，＆＃34; startPoint＆＃34;：null，＆＃34; endPoint＆＃34;：null，＆＃34; trailCheckpoints＆＃34;：null，＆＃34;输入＆＃34;：2，＆＃34; dificulty＆＃34;：null，＆＃34;持续时间＆＃34;：＆＃34; 2 1/2 - 3 h＆＃34;，＆＃34; minDuration＆＃34;：＆＃34; 00：00：00＆＃34;，＆＃34; maxDuration＆＃34;：＆＃34; 00：00：00＆＃34;，＆＃34;季节性＆＃34;：＆＃34; mediu＆＃34;，＆＃34; equipmentLevel＆＃34;：null，＆＃34; trailMarking＆＃34;：null，＆＃34; hasTrailType＆＃34;：false }，

我想的可能是它的EF Core，并且已经进行了第二次尝试（即将dblude（）添加到dbContext查询中）：

[HttpGet("[action]")]
public IEnumerable<HikingTrail> HikingTrails()
{
    var dbOptions = new DbContextOptionsBuilder<HikingTrailContext>();
    dbOptions.UseSqlServer("Server = (localdb)\\mssqllocaldb; Database = HikingApp");
    var dbContext = new DAO.HikingTrailContext(dbOptions.Options);
    return dbContext.HikingTrails.Include( x => x.MountainRange).ToList();
}

无法在邮递员中获得任何回复。

编辑：

public class HikingTrailContext : DbContext
{
    public HikingTrailContext(DbContextOptions<HikingTrailContext> options) : base(options)
    {

    }
    public HikingTrailContext():base(){


    }

    public DbSet<HikingTrail> HikingTrails { get; set; }
    public DbSet<MountainRange> MountainRanges { get; set; }
    public DbSet<TrailScrapingSessionInfo> TrailScrapingHistory { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {

    }
}

public class HikingTrail
{
    [Key]
    public int HikingTrailId { get; set; }
    public HikingTrail() { }

    public MountainRange MountainRange { get; set; }
    public String Name { get; set; }
    public Location StartPoint { get; set; }
    public Location EndPoint { get; set; }
    public List<Location> TrailCheckpoints { get; }
    public TrailType Type => TrailType.Undetermined;
    public String Dificulty { get; set; }
    public String Duration { get; set; }
    public TimeSpan MinDuration { get; set; }
    public TimeSpan MaxDuration { get; set; }
    public String Seasonality { get; set; }
    public String EquipmentLevel { get; set; }
    public String TrailMarking { get; set; }
    public String URL;
    public bool HasTrailType
    {
        get
        {
            return this.Type != TrailType.Undetermined;
        }
    }

    public override bool Equals(object obj)
    {
        return (((HikingTrail)obj).Name == this.Name);
    }

    public override int GetHashCode()
    {
        int hash = 17;
        // Suitable nullity checks etc, of course :)
        hash = hash * 23 + Name.GetHashCode();
        hash = hash * 23 + Type.GetHashCode();
        hash = hash * 23 + StartPoint.GetHashCode();
        return hash;
    }

    public override string ToString()
    {
        return Name.ToString();
    }
}

编辑：我在 dbContext.HikingTrails.Include（x =＆gt; x.MountainRange）.xhere（x =＆gt; x.MountainRange！= null）.ToList（）; 上分析了数据库，生成的查询是好的，这意味着它也有MountainRange的Name列。

P.S。：几个字段为空，但那些字段还没有数据。

Answer 1

找到一个解决方案， Projection 到匿名类型。还必须注意不要有两个具有相同名称“名称”的字段

[HttpGet("[action]")]
public dynamic HikingTrails3()
{
    var dbOptions = new DbContextOptionsBuilder<HikingTrailContext>();
    dbOptions.UseSqlServer("Server = (localdb)\\mssqllocaldb; Database = HikingApp");
    var dbContext = new DAO.HikingTrailContext(dbOptions.Options);

    var trails = dbContext.HikingTrails.Include(x => x.MountainRange).
    Select( i =>new { Name= i.Name, MountainRangeName = i.MountainRange.Name, i.Duration,
    i.Dificulty,i.EquipmentLevel, i.Seasonality, i.Type }).ToList();
    return trails;
}

Asp.net Core没有序列化我的新类型

1 个答案: