C#•5w ago

Unable to create a 'DbContext' of type ''. The exception 'The entity type 'SelectListGroup' requires

Hello, everytime I want to create a migration I get this Error:

Unable to create a 'DbContext' of type ''. The exception 'The entity type 'SelectListGroup' requires a primary key to be defined. If you intended to use a keyless entity type, call 'HasNoKey' in 'OnModelCreating'. For more information on keyless entity types, see https://go.microsoft.com/fwlink/?linkid=2141943.' was thrown while attempting to create an instance. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

Unable to create a 'DbContext' of type ''. The exception 'The entity type 'SelectListGroup' requires a primary key to be defined. If you intended to use a keyless entity type, call 'HasNoKey' in 'OnModelCreating'. For more information on keyless entity types, see https://go.microsoft.com/fwlink/?linkid=2141943.' was thrown while attempting to create an instance. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

The funny thing is, I dont hae anywhere "SelectListGroup" defined like its nowhere. Can someone help me there? https://paste.mod.gg/pdgbqxsiwibr/2

BlazeBin - pdgbqxsiwibr

A tool for sharing your source code with the world!

15 Replies

KasumiOP•5w ago

please ping on reply

FusedQyou•5w ago

Do you use SelectList anywhere? @Kasumi It might be you use this in a class you use as a DB class. One solution is notating it with [NotMapped] Please also share Idea and ApplicationTag

KasumiOP•5w ago

Added And yes I use SelectListItem for the TagList

FusedQyou•5w ago

Yes, put NotMapped there

public class IdeaViewModel
{
    public long Id { get; set; }
    public string Title { get; set; }
    public string Description { get; set; }
    public DateTime CreatedDate { get; set; }
    public bool IsPublic { get; set; }
+
+   [NotMapped]
    public List<SelectListItem> TagList { get; set; } = new();
    public List<string> TagIds { get; set; } = new();
}

public class IdeaViewModel
{
    public long Id { get; set; }
    public string Title { get; set; }
    public string Description { get; set; }
    public DateTime CreatedDate { get; set; }
    public bool IsPublic { get; set; }
+
+   [NotMapped]
    public List<SelectListItem> TagList { get; set; } = new();
    public List<string> TagIds { get; set; } = new();
}

EF will always attempt to store the object into the database and if it fails it throws Consider using a separate class for DB data so this is avoided Or is this supposed to be stored in the database? Because if so, you need to update your fluent configuration

KasumiOP•5w ago

Well now I get this: To change the IDENTITY property of a column, the column needs to be dropped and recreated. ut I already dropped it Idk I'm just frusted and somehow get this working and trying everything I find / get recommended and so on

FusedQyou•5w ago

Well I can't help you with something you don't know Previous point still stands, you should use separate classes for this A bit of extra work but generally database classes look very different. Especially because EF does a lot of conventions based on how the class is formed

KasumiOP•5w ago

Yes, but its planned that the TagIds are Listed in the DB because why not? Okay you know a fix for that?

Salman•5w ago

Btw it's weird to put DB Model and VM in a same class , you should make a separate folder for VM and put VM classes there to keep things organized

FusedQyou•5w ago

Well yes that's what I already mentioned, separate the concerns DB class for the DB, not a view model that does both Sorry idk I think it's because you added an Id of type long

Salman•5w ago

What did you do to get this error

FusedQyou•5w ago

Again, make a separate class and properly scaffold it Alternatively try putting [PrimaryKey] above your id

KasumiOP•5w ago

Nothing, I just created the migration and and wanted to update the database Well Scaffolding doesnt work either. The last time I used the scaffolding from VS it created everything but it saved nothing into the Database because it couldnt get the UserId because the Scaffold thing is too dumb to check that and add the code

Salman•5w ago

I'd remove the migrations folder and would apply it and update the db from scratch

KasumiOP•5w ago

okay Fixed thank you :love_bun: $close

MODiX•5w ago

If you have no further questions, please use /close to mark the forum thread as answered

Gaming

Programming

Unable to create a 'DbContext' of type ''. The exception 'The entity type 'SelectListGroup' requires

Did you find this page helpful?