I have an SQL database with 200 tables.
I changed the primary key on one "basic" table.
I changed ALL foreign keys referring to that table, in more than 20 tables.
I Updated the LinQ model (right-click, update model from DB) to reflect the changes in the model itself.
As a result, 3 tables disappeared from the model (they are not visible in the graphical view of the model), and I get errors: Error 3013: mapping problem from line xxxx: no mapping fot table "tablename"
Trying to update again, if I look on the details of the tables to add, I can't see the 3 tables "lost": they are in the DB, I'm sure, and SEEM to be in the model, because they aren't in the list of tables that I can add, but they aren't in the model.
What could I do in this situation?
It seems solved ... one friend suggested to open manually the edmx file with an editor (I used Notepad++), and remove any reference at the 3 tables (they were there), save, and try the update again, and the tables appeared again.
Related
I have an ASP.NET Core application that uses EF6 for dealing with a third-party application's database.
Everything is working as expected, but I'm unable to insert rows into a joining table.
I have two tables, Users and Groups, and a joining table GroupUser that identifies which users are members of which groups. Users has a PK of UserId, and Groups has a PK of GroupId.
GroupUser has only 3 columns: GroupId, UserId and another column (which is irrelevant for this post). The two foreign keys in this table identify a unique record.
Every time I try to insert into GroupUser, I get the inner exception
The table/view does not have a primary key defined. The entity is read-only
The error is correct. There is no PK, but both of the FKs are marked as keys in the model. Shouldn't VS be able to use those as a PK somehow?
The inserts used to work as some point, but required some manual modification of the .edmx file as XML in order to work. Unfortunately, our version control records containing this modification have been lost (and I wasn't the one originally working on this).
I've looked at and tried about a dozen articles around this, but they generally have to do with views instead of tables, so don't seem applicable to my case. The ones that did seem applicable didn't solve the issue.
The only other clue I have for a solution is this comment I found in the code:
// Important note: If you have updated the edmx file in the [redacted]
// project and suddenly start having problems, the edmx file may need to be
// edited as an xml file so that you can make changes necessary to make
// VS believe that the GroupUser table has a primary key. See revision #[redacted]
I'm able to insert into User and Group tables just fine, and as I've said, I don't have access to the revision log mentioned.
Edit: The database is for a third-party application, and unfortunately, it's not as simple as just modifying the table to add a PK. I wish it was. Problem would be solved. But I've been advised by the vendor not to make this change, as it may have unexpected consequences, and would void our support.
How can I 'trick' EF into thinking the table has a key? I'm also open to other workarounds. Modifying the DB structure is currently out of the question.
I am very new to EF programming.
My application gets the data from existing database. (DB first)
Now I have come to situation where I want to update my model to newer DB. basically the core schema is same as previous but has some modification in the table.
When I change the DB name for app.config and update the model it gives list of error
have I missed something?
When you do an update it merges the model you have with the DB that you update from. Additional columns are added to your existing entities but columns that you have removed from the DB are not removed from your entities and you need to remove these mappings yourself.
If you know which tables have columns removed it sometimes easier to delete the entity from your model and then do an update to reload it from the DB.
If you've don't know what tables or there have been many then it may be easier to delete all entities from your model and just do a full Update to reload the the new DB structure.
Ok, so I have 2 entities: Course and Industry
The industry entity is just a reference table which lists all available Industries that can be tagged to a course, to categorizing them. I put in a many to zero or one relationship (a course can choose to have an industry or not, while an industry can be tagged with many courses).
I know I've played around with the diagrams a bit, adding and removing associations in the past.
Now here is the odd part: The column mappings for Course has 2 similar columns, IndustryId and Industry_Id
I suspect it's from a past association, but thought EF would have taken care of that.
Here is the problem:
In my view that creates the course, the IndustryId is the property which needs to be populated. When I create new courses, I see the IndustryId in the database populated.
However, when I access Industry's properties through Course (Course.Industry.Description) nothing is populated. It can't seem to get the Industry entity.
I see the IndustryId populated in the db, so I tried to populate the Industry_Id column. That fixed it.
Weird enough, the property declared in the model is IndustryId, so that column is populated in the db. But when I try to get Industry entities through Course, it needs the Industry_Id, which I don't quite know where it is from.
Anyone have any ideas?
It sounds like in your updating from the database, you changed the column name on your tables from Industry_Id to IndustryId. The next time you updated from the database, EF5 (which can't determine that this is the same column, as it matches on names) dropped the mapping for Industry_Id, and added a new column called IndustryId.
However, you had already created the foreign-key mapping in your EDMX file based on the Industry_Id column - which is why you get the issue around needing it when loading related records.
In general, when using Database-First, whenever you rename a column in the database, you need to update your EF5 model and update / correct any such discrepancies.
I am using Database First EF to generate model from the existing database. When I first generated the models, it ignores only one of the table, the entity was not added to EDMX, no model file is created for the table and no context is created for the entity.
When I tried to explicitly add the table to EDMX (when generating the model, selected the specific table first and then updated the model with all the other tables from the database), it complained with the following error.
Two entities with possibly different keys are mapped to the same row. Ensure these two mapping fragments map both ends of the AssociationSet to the corresponding columns.
This specific table has two columns which are primary keys of some other tables and both the columns are specified as Primary keys for the table.
Am I doing something wrong or should I handle this table differently since it has two columns defined as Primary Keys? Any suggestions greatly appreciated!
You are not doing anything wrong. Your table is junction table for many-to-many relation. You don't need that table in the model because EF (in contrast to database) can handle many-to-many relation directly without any intermediate. The table is actually mapped on behind of the many-to-many relation - you will see that in mapping details window.
Btw. you are not using code first. Code first = no EDMX.
When I delete a column from an already existing db from an already existing database model, right clicking on the .edmx "Update model from Database" does not remove deleted columns from the model (column existed in the model and db before but was removed from db) .
One thing that I have noticed is that my mapping detals are not matching up with my .edmx. Mapping detals are up to date with database but they dont' match that of the .edmx.
Is this expected behavior? Thanks!
[Using asp.net 4.0/EF4.1]
I have found that, when I update the underlying database table, the best approach is to delete the mapped table from the edmx designer, and then do Update Model from Database.