Why am I getting this error No mapping specified for the following EntitySet AssociationSet - Entity1

Question

I m using Entity Framework 4 with the Model First approach   I started the project  designed the entities and generated the database  Everything worked fine   Then I needed to go back and add another entity to my model  However  as I drag an entity to the EDMX I get this error     Alright  I just need to map Entity1 to a table   But hey  I m using Model First approach  I expect it to create the table for me when I generate the DDL   How do I work around this error

User · Answer

Update Model from Database doesn t works for me    I had to remove the conflicted entity  then execute Update Model from Database  lastly rebuild the solution  After that  everything works fine

User · Answer

I had a table change and it created another entity with a number 1 at the end  such as MyEntity1 and a MyEntity  as confirmed by the edmx model browser  Something about the two entities together confused the processing   Removal of the table and re-adding it fixed it     Note that if TFS is hooked up  then do a check-in of the edmx in after the delete  Then and only then get the latest and re-add it in a definite two step process  Otherwise TFS gets confused with the delete and re-add of same named entity ies  which seems to cause problems

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In my case  another developer had removed some of the tables from the underlying database  When I realised this  and removed these tables from the entity  the problem was solved  Wasn t as obvious as it sounds

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Error 3027  No mapping specified for the following EntitySet AssociationSet     quot  - Entity Framework headaches  If you are developing model with Entities Framework then you may run into this annoying error at times   Error 3027  No mapping specified for the following EntitySet AssociationSet  Entity or Association Name   This may make no sense when everything looks fine on the EDM  but that s because this error has nothing to do with the EDM usually  What it should say is  quot regenerate your database files quot   You see  Entities checks against the SSDL and MSL during build  so if you just changed your EDM but doesn t use Generate Database Model    then it complains that there s stuff missing in your sql scripts  so  in short  the solution is   quot Don t forget to  Generate Database Model every time after you update your EDM if you are doing model first development  I hope your problem is solved quot

User · Answer

Had this error when I had deleted a table from the database  Solved it by right clicking on EDMX diagram  going to Properties  selecting the table from the list in the Properties window  and deleting it  using delete key  from the diagram

User · Answer

Sharing this for other people  In my case  we were working on a shared MVC solution  and using a common module for tables that we use for dropdowns  I got the error when I updated the Entity model by adding a new table  It turns out that when I updated the the EDMX  it probably updated my rights access on the database  which resulted to not having access to that certain table giving me no mapping specified   Just re-adding and giving access to my user solved the problem

User · Answer

A quicker way for me was to delete the tables and re-add them  It Auto-mapped them

User · Answer

Go to Solution Explorer  click the Search button Leave checked both Search within file content and Search External Files Type the entities name which your mapping isn t recognizing   Delete all files RELATED to the problem  Those will probably be named after the same missing entity  DO NOT delete any file with your Context Class name on the file  specially if their extensions are  cs or  tt  In the Context  cs file  remove all lines of codes referencing the missing entity  They will look like this   public virtual DbSet lt  Entity1 gt  Entity1   get  set       This error is common to tables deleted from the database    When one drops a table in the database  or one just changes the web config connectionStrings for the EF Mapped database  to point to a new one and not the one used to generate the original mappings is the problem   It is this new db these entities with the 3027 error aren t present

User · Answer

I found I was getting the same error because I had forgot to create referential constraint after creating an association between two entities

User · Answer

For those who are using Database First approach all you have to do after inserting a new entity is to Generate Database From Model again by right click on your  edmx file and select Generate Database From Model

User · Answer

I ran into the same error  but I was not using model-first  It turned out that somehow my EDMX file contained a reference to a table even though it did not show up in the designer  Interestingly  when I did a text search for the table name in Visual Studio  2013  the table was not found    To solve the issue  I used an external editor  Notepad    to find the reference to the offending table in the EDMX file  and then  carefully  removed all references to the table  I am sorry to say that I do not know how the EDMX file got into this state in the first place

User · Answer

I had set everything correctly  cardinalities and dependent properties  but could not figure out why I keep receiving error  Finally figured out that  EF generated a column in dependent table on its own  table tablecolumn  and it does not have any relation to the table  so no mapping was specified  I had to delete the column in EDMX file and rebuild the solution which fixed the issue  I am using DB approach

User · Answer

I had the error when I was trying to make a custom result for a stored procedure and assumed it had to be an entity   The solution was that I just made a complex type in the Model browser and assigned that as a result to the  Edit function imports    I will add it here since it looks like this question is where google takes you when you get this error

User · Answer

I think I got this from not explicitly deleting some tables from the edmx before renaming and re-adding them   Instead  I just renamed the tables and then did an Update Model from Database  thinking it would see them gone  and delete them from model   I then did another Update Model from Database and added the renamed tables   The site was working with the new tables  but I had the error   Eventually  I noticed the original tables were still in the model   I deleted them from the model  click them in edmx screen  delete key   and then the error went away

User · Answer

If you are not using model-first  Double click  edmx  file - gt select all and delete all entity models - gt  save - gt  right click  update model from database - gt select required tables - gt finish and save

User · Answer

This is because of the way EF4 works with model-first   When you first create a model-first model  it s in a state that the SSDL does not exist  You can drag entities  associate them and so forth and yet  if you take a look at the SSDL on the EDMX file  you will see that none of the entities have an associated storage table in the SSDL   That changes when you click the Generate Database From Model context menu item  The confusing part is that this action does more than simply generating a DDL script  In fact  it changes the EDMX file to include SSDL information  From this point on  the EDMX file will enter a state in which every entity in the designer CSDL must map to an entity in the SSDL  If one does not map  it will trigger a compile time error       No mapping specified for the following EntitySet AssociationSet -  EntityName    Another interesting fact is that it s not the kind of error that will prevent compilation  It will  indeed  generate the output class library  Shouldn t it be a warning or something   To prevent this error  All you have to do after inserting a new entity is to Generate Database From Model again  That will update the SSDL and fix the mappings   EDIT  If you are not using model-first and you  update from database   you will also have this error in the case you deleted a table in DB Server  This is because Entity Framework will not automatically delete the entity for you  Delete the entity manually and the error will go away

[.net] Why am I getting this error: No mapping specified for the following EntitySet/AssociationSet - Entity1?

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