使用实体框架核心从自相关表中排除重复结果

如何解决使用实体框架核心从自相关表中排除重复结果

我需要从财务会计 web-api 软件的帐户创建分层树我创建了一个具有自我关系的表，但得到了重复的记录。

数据模型：

public class Account
{
    public int AccountId { get; set; }

    public int AccountCode { get; set; }

    [required]
    public string AccountName { get; set; }
    
    public int AccountParentCode { get; set; }
    public int? AccountParentId { get; set; }

    [IgnoreDataMember]
    public Account AccountParent { get; set; }
            
    public ICollection<Account> AccountChields { get; set; }
}

返回值给api：

return _context.Accounts.ToListAsync();

我的输出：

    [  {
    "accountId": 147,"accountCode": 1,"accountName": "Test1","accountParentCode": 0,"accountParentId": null,"accountChields": [
      {
        "accountId": 149,"accountCode": 11,"accountName": "Test11","accountParentCode": 1,"accountParentId": 147,"accountChields": [
          {
            "accountId": 152,"accountCode": 113,"accountName": "Test113","accountParentCode": 11,"accountParentId": 149,"accountChields": null
          },{
            "accountId": 153,"accountCode": 114,"accountName": "Test114",{
            "accountId": 154,"accountCode": 115,"accountName": "Test115","accountChields": null
          }
        ]
      },{
        "accountId": 150,"accountCode": 16,"accountName": "Test16","accountChields": null
      },{
        "accountId": 151,"accountCode": 18,"accountName": "Test18","accountChields": null
      }
    ]
  },{
    "accountId": 148,"accountCode": 2,"accountName": "Test2","accountChields": null
  },{
    "accountId": 149,"accountChields": [
      {
        "accountId": 152,{
        "accountId": 153,{
        "accountId": 154,{
    "accountId": 150,{
    "accountId": 151,{
    "accountId": 152,{
    "accountId": 153,{
    "accountId": 154,"accountChields": null
  }
]

我刚开始使用 .Net 技术，有没有办法完成这项任务，或者我是否必须改变我对设置数据库的看法？

谢谢;

解决方法

最好清理数据库中的数据，但您可以使用此代码排除重复数据：

 _context.Accounts.Distinct().ToListAsync();

,

有自我关系但得到重复记录的表

可以先找到所有的根元素，然后依次找到对应的子元素。

另外，你不需要AccountParentCode属性，你可以通过AccountParent获取父元素的ParentCode /strong>。

下面是一个例子，你可以参考一下。

控制器

[Route("api/[controller]")]
[ApiController]
public class ValuesController : ControllerBase
{
    public DailyCoreMVCDemoContext db;
    public ValuesController(DailyCoreMVCDemoContext _db)
    {
        db = _db;
    }
    [HttpGet]
    public async Task<string> test()
    {
        var allrootAccount = await db.Accounts.Where(m => m.AccountParentId == null).ToListAsync();
        var test = await db.Accounts.ToListAsync();
        allrootAccount.ForEach(t =>
        {
            t.AccountChields = GetSubordinateAccounts(test,t);
        });
        string result = JsonConvert.SerializeObject(allrootAccount,Formatting.None,new JsonSerializerSettings()
                    {
                        ReferenceLoopHandling = ReferenceLoopHandling.Ignore
                    });
        return result;
    }
    //a recursive method to get all subordinate Accounts
    public static List<Account> GetSubordinateAccounts(List<Account> allAccounts,Account superordinateAccount)
    {
        var result = new List<Account>();
        var subordinate = allAccounts.Where(a => a.AccountParentId == superordinateAccount.AccountId & a.AccountId != a.AccountParentId).ToList();
        if (subordinate.Count != 0)
        {
            result.AddRange(subordinate);
            foreach (var subo in subordinate)
            {
                result.AddRange(GetSubordinateAccounts(subordinate,subo));
            }
        }
        return result;
    }
}

结果