在.NET核心中的數據庫視圖

Question

我有一個從我爲CRUD設置的數據庫注入的表。

ID EID  Task   entrydate Level 
1 1 Demographics 2017-02-23 2 
2 0 Demographics 2017-02-23 2 
3 1 Progress Notes 2017-03-06 2 
4 1 Demographics 2017-03-06 3 
5 1 Assessments  2017-03-06 3 
6 1 Assessments  2017-01-25 1 

但是，要以對客戶端有意義的方式顯示數據，我需要按entrydate列列出級別數據。

ID EId  Task   25 Jan 2017 23 Feb 2017 06 Mar 2017 
1 1 Demographics  NULL   2   NULL 
2 0 Demographics  NULL   2   NULL 
3 1 Progress Notes  NULL   NULL   2 
4 1 Demographics  NULL   NULL   3 
5 1 Assessments   NULL   NULL   3 
6 1 Assessments   1   NULL   NULL 

我一直致力於在控制器和視圖中使用LINQ來在視圖中創建正確的表。

控制器：

public IActionResult Index(int id) 
    { 
     HttpContext.Session.SetInt32("EmployeeID", id); 
     var model = db.EmployeeTask 
      .Where(h => h.EmployeeId == id) 
      .OrderByDescending(h => h.Entrydate); 

     return View(model); 
    } 

查看網頁：

<table class="table"> 
<thead> 
    <tr> 
     <th> 
      @Html.DisplayNameFor(model => model.KeyTask) 
     </th> 
@foreach (var group in Model.GroupBy(item => item.Entrydate)) 
{ 
     <th> 
      @group.Key.Date 
     </th> 
} 
     <th></th> 
    </tr> 
</thead> 
<tbody> 
@foreach (var group in Model.GroupBy(item => item.KeyTask)) { 
    <tr> 
     <td> 
      @group.Key 
     </td> 
     @foreach (var item in group) 
     { 
      <td> 
       @Html.DisplayFor(modelItem => item.Acceptable) 
      </td> 

     } 
    </tr> 
} 
</tbody> 
</table> 

通過我的結果，我幾乎沒有。

View from MVC

我失去了一些東西從接受的數據不與entrydate列匹配。我是走在正確的道路上嗎，還是我走的儘可能遠，因爲LINQ會帶我並需要嘗試另一種方法？

Answer 1

經過大量的搜索，閱讀，試驗和錯誤，我找到了一種方法來完成這項工作。

首先，我意識到LINQ表達式不是我需要去的方式。我需要單獨構建行。由於數據具有動態列，因此DBSet無法工作。所以我在SQL中建立了一個Pivot查詢;

DECLARE @cols NVARCHAR (MAX), 
    @StartDate date = '03/01/2017', 
    @EndDate date = '03/20/2017', 
    @Id nvarchar(10) = 1 

SELECT @cols = COALESCE (@cols + ',[' + CONVERT(NVARCHAR, entrydate, 106) + 
    ']', 
    '[' + CONVERT(NVARCHAR, entrydate, 106) + ']') 
    FROM (SELECT DISTINCT entrydate 
      FROM EmployeeTask 
      WHERE entrydate >= @StartDate AND entrydate <= @EndDate 
      AND EmployeeId = @Id) PV 
    ORDER BY entrydate DESC 

DECLARE @query NVARCHAR(MAX) 
SET @query = '   
      SELECT * FROM (SELECT KeyTask, acceptable, entrydate 
         FROM EmployeeTask 
         WHERE EmployeeId = ('+ @Id +') 
         Group by KeyTask, acceptable, entrydate) x 
      PIVOT (SUM(acceptable) FOR entrydate IN (' + @cols + ')) p 
      '  
EXEC SP_EXECUTESQL @query 

這給了我想要顯示的表，但如何讓它顯示在MVC 6？

首先，我發現this SO post和Petr Vobornik的答案正是我所需要的。我不得不修改它並把它添加到我的控制器：

private static List<Dictionary<string, object>> LoadData(string sqlSelect, 
    params object[] sqlParameters) 
    { 
     var table = new List<Dictionary<string, object>>(); 
     using (var ctx = new DBContext()) 
     { 
      ctx.Database.GetDbConnection(); 
      ctx.Database.OpenConnection(); 
      using (var cmd = ctx.Database.GetDbConnection().CreateCommand()) 
      { 
       cmd.CommandText = sqlSelect; 
       foreach (var param in sqlParameters) 
        cmd.Parameters.Add(param); 
       using (var reader = cmd.ExecuteReader()) 
       { 
        while (reader.Read()) 
        { 
         var row = new Dictionary<string, object>(); 
         for (int i = 0; i < reader.FieldCount; i++) 
          row[reader.GetName(i)] = reader[i]; 
         table.Add(row); 
        } 

        if (table == null) 
        { 
         var row = new Dictionary<string, object>(); 
         for (int i = 0; i < 1; i++) 
          row[reader.GetName(i)] = "None"; 
         table.Add(row); 
        } 
       } 
      } 
     } 
     return table; 
    } 

if語句用來添加一個空行，這樣仍會生成列表，但它不包含任何內容。這樣，如果查詢不返回任何內容，仍然可以加載一個空視圖（請參閱下面的視圖）。

我說在我的控制器SQL連接：

public IActionResult Index(int id, string datestart, string dateend) 
    { 
     HttpContext.Session.SetInt32("EmployeeID", id); 

     if(datestart == null) 
     { 
      var setdate = DateTime.Now; 
      datestart = setdate.AddMonths(-3).ToString(); 
     } 

     if(dateend == null) 
     { 
      dateend = DateTime.Now.ToString(); 
     } 

     var start = new SqlParameter("@StartDate", datestart); 
     var end = new SqlParameter("@EndDate", dateend); 
     var EmpId = new SqlParameter("@Id", id); 
     var tasks = LoadData("EXECUTE dbo.TaskView @StartDate, @EndDate, 
        @Id",start,end,EmpId); 

     ViewBag.start = DateTime.Parse(datestart); 
     ViewBag.end = DateTime.Parse(dateend); 
     return View(tasks); 
    } 

接下來，我修改了瀏覽：

@model List<Dictionary<string, object>> 

@{ 
    ViewData["Title"] = "Employee Tasks"; 
} 

<h2>Employee Tasks</h2> 

<div class="panel panel-default"> 
<div class="panel-heading">Search by dates</div> 
<div class="panel-body"> 
    <form asp-controller="EmployeeTasks" asp-action="Index"> 
     <label>Start Date</label> 
     <input type="date" name="datestart" id="start" value=@ViewBag.start 
      /> 
     <label>End Date</label> 
     <input type="date" name="dateend" id="end" value=@ViewBag.end /> 
     <input type="submit" value="Search" /> 
    </form> 
    </div> 
</div> 

<p> 
    <a asp-action="Create">Add New Employee Task</a> 
</p> 

@if (Model.FirstOrDefault() != null) 
{ 
    <table class="table table-bordered"> 
    @foreach (var row in Model.FirstOrDefault()) 
    { 
     <th>@row.Key</th> 
    } 
    @foreach (var row in Model) 
    { 
     <tr> 
     @foreach (var column in row) 
     { 
      <td>@column.Value</td> 
     } 
     </tr> 
    } 
</table> 
} 

<div> 
    <a asp-controller="Employees" asp-action="Index">Back to Employee 
     Search</a> 
</div> 

最終的結果！

如果任何人有一個更簡單的方法，請張貼它作爲一個答案，所以我可以嘗試一下，不過這在.NET 1.1核心的偉大工程。