TempData in mvc concept

sankeerth m

5y740.NET

Can we call tempdata in constructor?

3 Replies

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Mageshwaran R5y ago
Hi SanKeerth,
Try this code:
public class MasterService
{
    private readonly IHttpContextAccessor _httpContextAccessor;
    private readonly ITempDataDictionaryFactory _tempDataDictionaryFactory;

    public MasterService(IHttpContextAccessor httpContextAccessor, ITempDataDictionaryFactory tempDataDictionaryFactory)
    {
        _httpContextAccessor = httpContextAccessor;
        _tempDataDictionaryFactory = tempDataDictionaryFactory;
    }

    public void DoSomething()
    {
        var httpContext = _httpContextAccessor.HttpContext;
        var tempData = _tempDataDictionaryFactory.GetTempData(httpContext);

        // use tempData as usual
        tempData["Foo"] = "Bar";
    }
}
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Kiran Mohanty5y ago
If you want to initialize TempData inside constructor , then you can . But if you wish to access any TempData value, then you can't. Its simply because dependency injection for any controller happens once the controller is initialized (that is after execution of constructor).

So if you are trying to access TempData value in constructor, value will be null.
0
Sachin Singh5y ago
TempData is used to store data for suceessive requests and it behaves differently than viewbag or viewdata.

what do you mean by a constructor, a controller constructor then when do you initialize it?

suppose , you store value in tempdata in any action method as
TempData["myTemp"]="Sachin";
Now,TempData has three flavours:-

1.Normal Read:-

now reas it in view as
@TempData["myTemp"];
now here the value will be null for next request as you have already read the value in view.

2.Peek Read:-
@{var val=TempData.Peek("myTemp")}

@val // it will print sachin

Here the value will be preserved for next request.
3.Keep after Read:-

@{

    var value=TempData["myTemp"];

    TempData.Keep("myTemp");

    }

@value // sachin

here also the value will be preserved for next request.
for more information:- https://www.sharpencode.com/article/MVC/how-to-pass-data-in-mvc/tempdata
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