在 ASP.Net Core 中将多个数据表组合成单个结果

Question

我有四个表在上下文中传递给页面。 4 个表中的每一个都由一个 Id 列连接。我想显示一个带有表格的页面，该表格结合了 4 个表格中的每一个表格的列。我还想对数据进行排序或搜索，并根据 1 个或所有表显示结果（例如，如果表 2 包含“名称”列，则搜索结果应仅显示与该名称匹配的行）

   public IList<AllTables> AllTableData {get;set;}

   public async Task OnGetAsync(
       string sortOrder,
       string queryFilter,
       string searchString)
   {
   //setting sort and search Params
   //......

   IQueryable<Table1> table1= _context.Table1.Select(f => f);
   IQueryable<Table2> table2= _context.Table2.Select(f => f);
   IQueryable<Table3> table3= _context.Table3.Select(f => f);
   IQueryable<Table4> table4= _context.Table4.Select(f => f);

   if (!String.IsNullOrEmpty(searchString))
   {
      // e.g. table1= table1.Where(s => s.Id.ToString() == searchString);
    }

    //Example for sorting
    switch (sortOrder)
    {
        case "Id":
           table1= table1.OrderBy(s => s.Id);
           break;
        case "Name":
           table2= table2.OrderBy(s => s.Id);
           break;
    }

    //How do I combine all four tables
    AllTableData = await (Join Tables 1-4).AsNoTracking().ToListAsync();
    }

我尝试创建一个新类，如下所示

  public Class AllTables
  {
     public Table1 Table1{get;set;}
     public Table2 Table2{get;set;}
     public Table3 Table3{get;set;}
     public Table4 Table4{get;set;}
  }

然后像这样组合数据

  AllTableData= await table1
            .Select(f=>new AllTables(
                f,
                table2.Where(g => g.Id== f.Id).FirstOrDefault(),
                table3.Where(h => h.Id== f.Id).FirstOrDefault(),
                table4.Where(i => i.Id== f.Id).FirstOrDefault(),
                )).AsNoTracking().ToListAsync();

这给了我完整的表格数据，但是当我尝试根据 table2.Name 进行排序时，排序不起作用。

Answer 1

您可以通过以下方式做到这一点：

IQueryable<Table1> table1 = _context.Table1;
IQueryable<Table2> table2 = _context.Table2;
IQueryable<Table3> table3 = _context.Table3;
IQueryable<Table4> table4 = _context.Table4;

var query = 
  from t1 in table1
  join t2 in table2 on t1.Id equals t2.Id into g
  from t2 in g.DefaultIfEmpty()
  join t3 in table3 on t1.Id equals t3.Id into g
  from t3 in g.DefaultIfEmpty()
  join t4 in table4 on t1.Id equals t4.Id into g
  from t4 in g.DefaultIfEmpty()
  select new AllTables
  {
     Table1 = t1,
     Table2 = t2,
     Table3 = t3,
     Table4 = t4
  };
 
if (!String.IsNullOrEmpty(searchString))
{
    query = query.Where(s => s.Table1.Id.ToString() == searchString);
}

//Example for sorting
switch (sortOrder)
{
    case "Id":
       query = query.OrderBy(s => s.Table1.Id);
       break;
    case "Name":
       query = query.OrderBy(s => s.Table2.Name);
       break;
}

var AllTableData = await query.AsNoTracking().ToListAsync();