I create entity outside my Project
this is solution Explorer
My entity Post
[Table("Post")]
public partial class Post
{
public int PostID { get; set; }
[Required]
[StringLength(256)]
public string Title { get; set; }
[StringLength(256)]
public string Description { get; set; }
[StringLength(256)]
public string Picture { get; set; }
public int CategoryID { get; set; }
[StringLength(10)]
public string ViewNumber { get; set; }
public int UserID { get; set; }
public DateTime CreateDate { get; set; }
public int LikeNumber { get; set; }
public int? CommentID { get; set; }
}
My Post Controller
[HttpPost]
public ActionResult UpPost(Post model, HttpPostedFileBase txtImg)
{
var db = new ShareImageDbContext();
if (ModelState.IsValid)
{
if (txtImg != null)
{
txtImg.SaveAs(HttpContext.Server.MapPath("~/Images/")
+ txtImg.FileName);
var post = new Post();
post.PostID = model.PostID;
post.Title = model.Title;
post.Description = model.Description;
post.CategoryID = model.CategoryID;
var userSession = new UserLogin();
userSession = (UserLogin)Session[ShareImage.Common.CommonConstants.USER_SESSION];
post.UserID = userSession.UserID;
post.CreateDate = DateTime.Now;
post.Picture = txtImg.FileName;
db.Posts.Add(post);
db.SaveChanges();
return RedirectToAction("Index", "Homeuser");
}
else
{
ModelState.AddModelError("", "Đăng ảnh thất bại!");
}
}
return View(txtImg);
}
My Post Database
I inserted some post
I want to display all Post on View. And I call Model as below.
#model IEnumerable<Model.EF.Post>
and I call foreach
#foreach (var item in Model)
but it has an error:
Object reference not set to an instance of an object.
I can display my image in Images folder as code following, but I want to show more attribute of Post table such as Title, Discription, CreateDate...
#foreach(var imgPath in Directory.GetFiles(Server.MapPath("~/Images")))
{
var img = new FileInfo(imgPath);
<img src="#Url.Content(String.Format("~/Images/{0}", img.Name))" />
<hr />
}
Please guide me how to fix it, Thanks!
In your view use String.IsNullOrWhiteSpace for strings and
<img src="<%= ResolveUrl(item.Picture) %>" alt="" /> for images
Problem caused because somewhere you do not set or create object. You have reference that has null value. It raises in view or controller. It will be nice if you provide your error message.
Related
I have two classes in my database which are defined as classes, fed into entity and then called from the API
The full method is below for the calls. The first call works fine, the second throws the exception
public async Task<ActionResult<List<QuizForms>>> GetQuiz([FromQuery]string id)
{
var form = await _context.QuizForms.Where(t=>t.QuizId == id).ToListAsync();
if (form == null)
{
return NotFound();
}
var elem = new List<Element>();
foreach(var e in form)
{
var data = await _context.Element.Where(t => t.ElementId == e.ElementId).ToListAsync();
elem.AddRange(data);
e.Element.AddRange(elem);
}
return form;
}
When the var data line is hit, an excception is thrown
Microsoft.Data.SqlClient.SqlException (0x80131904): Invalid column name 'QuizFormsFormId'.
It looks like the name of the class and column name are being concatenated and the used as the query parameter.
The two classes look like this
public class QuizForms
{
[Key]
public int FormId { get; set; }
public string QuizId { get; set; } = "";
#nullable enable
public string? Title { get; set; }
public int? ElementId { get; set; }
public List<Element>? Element { get; set; }
public int? PreviousId { get; set; }
public int? NextId { get; set; }
#nullable disable
}
and
public class Element
{
[Key]
public int Id { get; set; }
public int ElementId { get; set; }
#nullable enable
public int? MathsId { get; set; }
public int? QuestionId { get; set; }
public int? InformationId { get; set; }
public int? AnswerId { get; set; }
#nullable disable
public string QuizId { get; set; } = "";
}
Is it because I'm not using Id for the primary key or do I need to do something else so the class and property aren't concatented like this?
Can anybody guide me how to display data from two tables in database in view page of MVC4 using razor?i googled it but i didnt find answer for this
LeadDetail.cs
public partial class LeadDetail
{
public int LeadID { get; set; }
public string LeadName { get; set; }
public virtual logintable logintable { get; set; }
}
EmployeDetail.cs
public partial class EmployeDetail
{
public int EmployeID { get; set; }
public int UserID { get; set; }
public string EmployeeName { get; set; }
public virtual logintable logintable { get; set; }
}
Parentview.cs in viewmodels folder
public class Parentview
{
public List<LeadDetail> LeadDetails { get; set; }
public List<EmployeDetail> EmployeDetails { get; set; }
public ParentsInformationViewModel(List<LeadDetail> _LeadDetails, List<EmployeDetail> _EmployeDetails) //Should i pass all the required parameters that i want to display in view ????
{
LeadDetails = _LeadDetails;
EmployeDetails = _EmployeDetails;
}
Homecontroller.cs
public ActionResult view()
{
List<LeadDetail> LeadObj = new List<LeadDetail> ();
List<EmployeDetail> EmployeObj = new List<EmployeDetail> ();
// get list of parents here
Parentview ParentInfoVMObj = new Parentview();
ParentInfoVMObj.LeadDetails = LeadObj;
ParentInfoVMObj.EmployeDetails = EmployeObj;
return View(ParentInfoVMObj);
}
see below sample
First Table
public class Table1
{
public int Id{ get; set; }
public string Name{ get; set; }
}
Second Table
public class Table2
{
public int Id{ get; set; }
public string Name{ get; set; }
}
ViewModel
public class ViewModelForTwoTables
{
public List<Table1> table1Data { get; set; }
public List<Table2> table2Data { get; set; }
}
see below example
public ActionResult TeamStat()
{
var players = db.Players().ToList();
var seasons = db.Seasons().ToList();
var view = new TeamStat()
{
Players = players,
Seasons = seasons
};
return View(view);
}
in view
#foreach (var player in Model.Players) { ....
#foreach (var player in Model.Seasons) { ....
I got the error Invalid object name 'dbo.Staffs'. but I'm not sure why. I actually deleted and recreated my database with EF because previously I had other errors. But I'm quite sure I recreated it correctly because I've done it in the same way for other programs and it works fine.
.edmx database diagram
Controller
private StaffPortalDBEntities1 db = new StaffPortalDBEntities1();
SqlConnection cnn = new SqlConnection(ConfigurationManager.ConnectionStrings["StaffPortalDBConnectionString"].ConnectionString);
[Authorize]
public ActionResult Index()
{
var userEmail = User.Identity.Name;
var model = db.Staffs.Where(i => i.Email == userEmail).Include("Histories").Include("CurrentApplications").FirstOrDefault();
return View(model);
}
I got the error is for the line var model = db.Staffs.Where(i => i.Email == userEmail).Include("Histories").Include("CurrentApplications").FirstOrDefault();
Generated Staff class
public partial class Staff
{
public Staff()
{
this.Histories = new HashSet<History>();
this.CurrentApplications = new HashSet<CurrentApplication>();
}
public int StaffID { get; set; }
public string Name { get; set; }
public string Email { get; set; }
public Nullable<decimal> AllocatedLeave { get; set; }
public Nullable<int> BalanceLeave { get; set; }
public virtual ICollection<History> Histories { get; set; }
public virtual ICollection<CurrentApplication> CurrentApplications { get; set; }
}
Try this:
var model = db.Staffs.Where(i => i.Email == userEmail).Include(x=>x.Histories).Include(x=>x.CurrentApplications).FirstOrDefault();
In my WebApi controller I have a few methods that return objects retrieved from a database which are serialized to Json. Everything works fine if a method serializes and returns only a single object, it fails when it tries to serialize a collection of objects.
This is my model class:
[Table("Athlete")]
public partial class Athlete
{
public Athlete()
{
Event = new HashSet<Event>();
User = new HashSet<User>();
}
[Required]
[StringLength(32)]
[DisplayName("First name")]
public string FirstName { get; set; }
[Required]
[StringLength(32)]
[DisplayName("Last name")]
public string LastName { get; set; }
[StringLength(32)]
[DisplayName("Sport")]
public string Sport { get; set; }
[Key]
[Column(TypeName = "numeric")]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public decimal Athlete_ID { get; set; }
[DataMember]
[Column(TypeName = "numeric")]
public decimal? Team_Team_ID { get; set; }
[NotMapped]
[DisplayName("Team")]
public string TeamName { get; set; }
[JsonIgnore]
public virtual Team Team { get; set; }
[JsonIgnore]
public virtual ICollection<Event> Event { get; set; }
[JsonIgnore]
public virtual ICollection<User> User { get; set; }
}
This works fine:
[HttpGet]
public IHttpActionResult GetById(int id)
{
var athlete = _db.Athlete
.Where(a => a.Athlete_ID == id)
.FirstOrDefault();
if (athlete != null)
{
return Json<Athlete>(athlete);
}
return NotFound();
}
The following method causes a serialization error (System.InvalidOperationException)
(The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset=utf-8'.)
The inner exception's message is "Self referencing loop detected for property 'ApplicationInstance' with type 'ASP.global_asax'. Path 'Request.Properties.MS_HttpContext.ApplicationInstance.Context'."
[HttpGet]
public IHttpActionResult GetAllAthletes()
{
var athletes = _db.Athlete.ToArray();
if (athletes != null)
{
return Ok(Json<IEnumerable<Athlete>>(athletes));
}
return NotFound();
}
I've already tried to change the serialization settings in WebApiConfig.cs like in this question but nothing has worked so far.
Any help would be appreciated.
I've managed to find a way to work-around this in a semi-elegant manner. I'm not completely happy with this but a man's gotta do what a man's gotta do.
In case anyone needs this in the future:
Create a class that implements the IHttpActionResult interface:
public class MyJsonResult : IHttpActionResult
{
object _value;
HttpRequestMessage _request;
public MyJsonResult(object value, HttpRequestMessage request)
{
_value = value;
_request = request;
}
public Task<HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken)
{
var response = new HttpResponseMessage()
{
Content = new StringContent(JsonConvert.SerializeObject(_value), Encoding.UTF8, "application/json"),
RequestMessage = _request,
StatusCode = HttpStatusCode.OK
};
return Task.FromResult(response);
}
}
Then use it in a following way:
[HttpGet]
public IHttpActionResult GetAllAthletes()
{
var athletes = _db.Athlete;
if (athletes != null)
{
return new MyJsonResult(athletes, Request);
}
return NotFound();
}
I'm having some doubts, maybe newbie doubts but I just got into ASP.NET MVC 4
Basically I would like to know the correct way of grabbing details of an Object inside a model.
In this case Image inside Contractor.
Model:
public class Contractor {
[Key]
public int ContractorID { get; set; }
[Required]
public string Name { get; set; }
[Required]
public string Address { get; set; }
public Image Avatar { get; set; }
}
public class Image {
[Key]
public int ImageID { get; set; }
[Required]
public string File_name { get; set; }
[Required]
public byte[] File_data { get; set; }
}
public class DATACRUD : DbContext {
public DbSet<Contractor> Companies { get; set; }
public DbSet<Image> Images { get; set; }
}
Controller:
private DATACRUD db = new DATACRUD();
public ActionResult GetContractorAvatar(int id)
{
Contractor contractor = db.Contractors.Find(id);
if (contractor == null)
{
return HttpNotFound();
}
Image avatar = contractor.Avatar;
Problem 1)
avatar == null, but is not suppose to be because when I created the object Contractor, I added the image sucessfully (I checked in the DB and it is there)
The solution I'm seeing is instead of having Image property in Contractor.cs model, I would just put a string property with the image key.
Problem 2)
Even If could grab the image key like I said in the previous problem, when I pass my mouse in Debug mode over
private DATACRUD db = new DATACRUD ();
db.Images is also empty...
return File(avatar.File_data, "image");
}
Because you haven't defined your Image navigation property as virtual, you will have to eager load the Image when loading a Contractor:
db.Contractors.Include("Avatar").SingleOrDefault(c => c.ContractorID == id);
OR
// using System.Data.Entity;
db.Contractors.Include(c => c.Avatar).SingleOrDefault(c => c.ContractorID == id);