I am attempting to read related data across three tables in ASP.NET CORE MVC 2.2 with Entity Framework Core.
To be more specific I am using this tutorial to build my project https://docs.microsoft.com/en-us/aspnet/core/data/ef-mvc/read-related-data?view=aspnetcore-2.2. I am using Eager Loading to read Job.JobTitle all the way from the Problem Index method. Reading this I realize I want to find where Problem navigation property that contains the Job entity of the JobTitle that the Problem is assigned to. But That would be a many to many relationship so I have thrown in a Result composite table to stop that.
From my research, adding the foreign key attributes can help. Which hasn’t. So how can I Render the JobTitle that the problem belongs too in the job index?
Job class:
public class Job
{
public int ID { get; set; }
public string JobTitle { get; set; }
public string JobDescription { get; set; }
public DateTime JobStartDate {get;set;}
public DateTime JobDeadline {get;set;}
public bool JobIsComplete{get;set;}
public ICollection<Result> Results {get;set;}
}Result class:
public class Result
{
public int JobID {get;set;}
public int ProblemID {get;set;}
[ForeignKey("Job")]
public Job Job {get;set;}
[ForeignKey("Problem")]
public Problem Problem {get;set;}
}
Problem class:
public class Problem
{
public int ID {get;set;}
public string ProblemTitle {get;set;}
public string ProblemDescription {get;set;}
public DateTime ProblemStartDate {get;set;}
public string ProblemFileAttachments {get;set;}
public int ProblemSeverity {get;set;}
public bool ProblemComplete {get;set;}
public ICollection<Result> Result {get;set;}
}Index method of ProblemController (please see comment to find bug):
public async Task<IActionResult> Index(string sortOrder, string currentFilter, string searchString, int? pageNumber)
{
ViewData["CurrentSort"] = sortOrder;
ViewData["ProblemIDSortParm"] = String.IsNullOrEmpty(sortOrder) ? "ProblemID_desc" : "";
ViewData["ProblemTitleSortParm"] = String.IsNullOrEmpty(sortOrder) ? "ProblemTitle_desc" : "";
ViewData["ProblemStartDateSortParm"] = sortOrder == "ProblemStartDate" ? "ProblemStartDate_desc" : "ProblemStartDate";
ViewData["ProblemSeveritySortParm"] = sortOrder == "ProblemSeverity" ? "ProblemSeverity_desc" : "ProblemSeverity";
ViewData["ProblemCompleteSortParm"] = sortOrder == "ProblemComplete" ? "ProblemComplete_desc" : "ProblemComplete";
ViewData["CurrentFilter"] = searchString;
//READ RELATED DATA HERE
var problems = from p in _context.Problems
.Include(p => p.Result)
.ThenInclude(j => j.Job.JobTitle)
select p;
//END OF READ RELATED DATA
if(searchString != null)
{
pageNumber = 1;
}
else
{
searchString = currentFilter;
}
if(!String.IsNullOrEmpty(searchString))
{
problems = problems.Where(p => p.ProblemTitle.Contains(searchString)
|| p.ProblemDescription.Contains(searchString));
}
switch (sortOrder)
{
case "ProblemID_desc":
problems = problems.OrderByDescending(p => p.ID);
break;
case "ProblemTitle_desc":
problems = problems.OrderByDescending(p => p.ProblemTitle);
break;
case "ProblemStartDate":
problems = problems.OrderBy(p => p.ProblemStartDate);
break;
case "ProblemStartDate_desc":
problems = problems.OrderBy(p => p.ProblemStartDate);
break;
case "ProblemSeverity":
problems = problems.OrderBy(p => p.ProblemSeverity);
break;
case "ProblemSeverity_desc":
problems = problems.OrderByDescending(p => p.ProblemSeverity);
break;
case "ProblemCompleteSortParm":
problems = problems.OrderBy(p => p.ProblemComplete);
break;
case "ProblemCompleteSortParm_desc":
problems = problems.OrderByDescending(p => p.ProblemComplete);
break;
default:
problems = problems.OrderBy(p => p.ProblemTitle);
break;
}
int pageSize = 20;
return View(await PaginatedList<Problem>.CreateAsync(problems.AsNoTracking(), pageNumber ?? 1, pageSize));
}ProblemIndex view, (please see comment to find where I am having problem):
@model PaginatedList<Pitcher.Models.Problem>
@{
ViewData["Title"] = "Problems";
}<h1>Index</h1><p><a asp-action="Create">Create New</a></p>
@*COPY AND PASTE THIS TAG HELPER METHOD TEXTBOX CUSTOMIZATION INTO OTHER VIEWS TO ENABLE SEARCHING.*@<form asp-action="Index" method="get"><div class="form-actions no-color"><p>
Find by name: <input type="text" name="SearchString" value="@ViewData["currentFilter"]" /><input type="submit" value="Search" button type="button" class="btn btn-primary" /> |<a asp-action="Index">Back to Full List </a></p></div></form><table class="table table-hover"><thead><tr><th><a asp-action="Index" asp-route-sortOrder="@ViewData["ProblemIDSortParm"]" asp-route-currentFilter="@ViewData["CurrentFilter"]">Problem ID</a></th><th><a asp-action="Index" asp-route-sortOrder="@ViewData["ProblemTitleSortParm"]" asp-route-currentFilter="@ViewData["CurrentFilter"]">Problem Title</a></th><th><a asp-action="Index" asp-route-sortOrder="@ViewData["ProblemStartDateSortParm"]" asp-route-currentFilter="@ViewData["CurrentFilter"]">Problem Start Date</a></th><th>
Problem File Attachments</th><th><a asp-action="Index" asp-route-sortOrder="@ViewData["ProblemSeveritySortParm"]" asp-route-currentFilter="@ViewData["CurrentFilter"]">ProblemSeverity</a></th><th><a asp-action="Index" asp-route-sortOrder="@ViewData["ProblemCompleteSortParm"]" asp-route-currentFilter="@ViewData["CurrentFilter"]">ProblemComplete</a></th><th>
Job Title</th><th></th></tr></thead><tbody>
@foreach (var item in Model) {<tr><td>
@Html.DisplayFor(modelItem => item.ID)</td><td>
@Html.DisplayFor(modelItem => item.ProblemTitle)</td><td>
@Html.DisplayFor(modelItem => item.ProblemDescription)</td><td>
@Html.DisplayFor(modelItem => item.ProblemStartDate)</td><td>
@Html.DisplayFor(modelItem => item.ProblemFileAttachments)</td><td>
@Html.DisplayFor(modelItem => item.ProblemSeverity)</td><td>
@Html.DisplayFor(modelItem => item.ProblemComplete)</td>
@* RENDER Job Title here *@
@Html.DisplayFor(modelItem => item.Result)
@* END render Job Title here *@<td><a asp-action="Edit" asp-route-id="@item.ID" button type="button" class="btn btn-primary btn-block" >Edit</a> <a asp-action="Details" asp-route-id="@item.ID" button type="button" class="btn btn-info btn-block">Details</a> <a asp-action="Delete" asp-route-id="@item.ID" button type="button" class="btn btn-primary btn-block">Delete</a></td></tr>}</tbody></table>
@{
var prevDisabled = !Model.HasPreviousPage ? "disabled" : "";
var nextDisabled = !Model.HasNextPage ? "disabled" : "";
}<a asp-action="Index"
asp-route-sortOrder="@ViewData["CurrentSort"]"
asp-route-pageNumber="@(Model.PageIndex - 1)"
asp-route-currentFilter="@ViewData["CurrentFilter"]"
class="btn btn-secondary @prevDisabled"
button type="button">
Previous</a><a asp-action="Index"
asp-route-sortOrder="@ViewData["CurrentSort"]"
asp-route-pageNumber="@(Model.PageIndex + 1)"
asp-route-currentFilter="@ViewData["CurrentFilter"]"
class="btn btn-secondary @nextDisabled"
button type="button">
Next</a>