I'm using .Net 4.5, entity framework 5, database first. I have a junction (many-to-many) table in my database. For this example lets say the table is "StudentsCourses":
Students
-PkStudentId
-Name
Courses
-PkCourseId
-CourseNumber
StudentsCourses
-FkStudentId
-FkCourseId
This works just fine right now. The 'generate model from database' creates a Student entity with a navigation property to the Course entity. But here is where the trouble is:
I need to add another column to the StudentsCourses table. Lets just call this column "CourseYear". So our junction table would now look like this:
StudentsCourses
-FkStudentId
-FkCourseId
-CourseYear
So, I've added this column to the database and ran "Update Model from Database" on the edmx. I would expect to see an entity created for StudentCourses, with a navigation property to both Students and Courses. But no such entity is created. I still see the same two tables (Students & Courses) with the same navigation property as before.
I've done a lot of reading and researching, but haven't really come across a clear-cut answer. There is a wealth of information on code-first which I can't apply to my scenario. Is there a way to get what I'm after? Is it as simple as adding a PkId to the StudentCourses table? SQL Replication is preventing me from doing this. I would think the composite should suffice, but maybe EF needs a PK to do it's magic? I read a little bit about manually setting relationships, but could not find anything speaking to my particular situation. It could be that I am just missing a simple step in the process of updating the edmx from database. I've done this plenty of times when: adding new tables, adding columns, deleting columns, etc. I'm following the same steps as I always do, but maybe I need to do something different in this case?
Thanks ahead of time for any help. It is greatly appreciated. Please let me know if any more information would help.
From what I've gathered it appears as though EF will not generate a model for a table that doesn't have a Primary Key.
I'm a bit late for this, but you have the answer in this thread Updating Entity Framework Model after adding a field to a previous look up only table
As they say here, you have to delete the relationship between Students and Courses in the designer. Then update your model from the database, and make sure StudentsCourses table is checked in the Tables branch of the Add tab.
I'm really new to Entity Framework (currently using EF5) and vs2012 and am having difficulty trying to figure something out.
I have an .edmx that was generated from my database. It has two tables in it: Item and 3rdPartyItem. In short, the Item table is the main table for all the company items while the 3rdPartyItem table is a table that is used to hold additional attributes for items. This 3rdPartyItem table was created by an outside company and is used with their software for the company, so I can't mess with either table. What I'm trying to do is show a list of Items in a grid but I need to show a combination of all the fields for both tables. In vs2012, if I create a relationship and make it 'zero-to-one' (because for each record in the Item table, there doesn't necessarily have to be one in the 3rdPartyItem table), vs complains about not being mapped correctly. When I set the mapping, it then complains that there's multiple relationships. I did some research and found that you can't create a relationship with 2 primary keys, so I was thinking that was the problem. But how can I change the .edmx so that in code, I can access Items and 3rdPartyItem like so:
var items = dbContext.Items;
items.3rdPartyItem.SomeField <--field from 3rdPartyItem table.
not too sure if it's even possible, but it would be very, very helpful if so. Any ideas?
What you're looking for is table-per-type (TPT) mapping inheritance. You can view an MSDN walkthrough here (although you'd want your base type to be instantiable):
http://msdn.microsoft.com/en-us/data/jj618293.aspx
I've a problem mapping just one table from database, I add several tables using "Update model from Database" function through Visual Studio 2010 interface, and everyone works as expected except one table!
Looking at "Model Browser" I can see the table doesn't appear under "Entity Types" but it is present under section "ObjectEntity.Store", so my POCO Generator create an entity related and I can't try to add it again from database but I can't access it through context (like context.table_name).
Tha table doesn't have particular form, there are just two key fields
Could someone help me?
Thanks
I guess it is junction table for implementing many-to-many relation, isn't it? In such case it is correct behavior. EF will hide this table because it is not needed in object oriented approach where many-to-many association can be modeled directly without helper entity. You will see in your model that those two related entities are connected by line with * - * multiplicity and each entity will contain navigation property which is collection of related entities. By manipulation with entities in these collections you are creating or removing records in that hidden table. That is the way how you work with such relation in EF.
I'm brand new to ASP.NET MVC (Literally just two days of learning on the fly). I'm trying to create a website using MVC, however, I've screwed something up in my solution.
I created this table that had foreign key constraints but I initially forgot to set up a primary key on the id field and forgot to set it identity specification to yes. So when I updated my DataModel and brought this table in, it showed every field as being the primary key and it showed the relationship to the other tables. So I went back to the database and changed the id field for the table to be the primary key and identity specification to yes.
I went back to the DataModel, tried to Update Model From Database, went to the refresh tab, expanded the tables, and selected the table I wanted to refresh, then click on "Finish".
The data model appeared to make the changes but it showed the relationships to the other tables twice.
So I thought I'd delete the table (entity) from the DataModel diagrahm and bring the table back in through Update Model From Database. But when I went back to the Update Model From Database...
Under the Add tab, the table isn't under the Tables
Under the Refresh tab, the table is listed, but when I select it and click on "Finish" the table doesn't reaapear in the diagrahm.
In the model browser...
Under Models
Entity Types, The entity isn't listed
Under Associations, The relationships no longer appear (obviously because the entity is gone).
Under Models.Store
Tables/Views, The table is listed.
Constraints, the relationships are shown.
I've tried dragging the table over to the diagrahm from the Model Browser, but that doesn't appear to work.
I've tried to right click in the diagrahm, add Entity but my table doesn't appear as a Base Type.
I've tried to google but I'm coming up with nothing. With this entity missing, I cannot even build my solution. Please help.
Try to delete the entity file and add it again. But you have to name it as previous entity and don't forget to delete the connectionString in web.config before add it.
If you don't know what I am saying just let me know.
Error 3007: Problem in Mapping Fragments starting at lines 186, 205: Non-Primary-Key column(s) [WheelID] are being mapped in both fragments to different conceptual side properties - data inconsistency is possible because the corresponding conceptual side properties can be independently modified.
I found several places on the web describing this error, but I simply don't understand them. (confused smiley goes here)
One
Two
Three
Four
There is something pretty fundamental here, I must be missing. Can you explain it, so that I understand it? Maybe using my real life example below?
Foreign key 1:N Wheels.Id -> Slices.WheelId
I add them to entity framework, and WheelId is not visible in the Slices-entity.
Doing some workaround (deleting the relationship from the db before adding tables to EF - then re-creating it and updating EF) I managed to get the WheelId to stay in Slices, but then I get the error mentioned at the top.
Since Slices.WheelId is an FK, you cannot expose it in your client model, period. There are ways to get the value, though.
var wheelId = someSlice.Wheels.ID;
Update In EF 4 you can do this by using FK Associations instead of independent associations.
Try to remove foreign property column from Entity set using entity model design it will solve your problem
For example
We have two tables one is customer and other one is order, using entity model design we added association between customers and orders when we do this Ado.net entity framework i will add navigation properties to both below tables.
Like
Customer.Orders - Here order is list
Order.Customer
One - Many relation.
So we need to remove property from with name CustomerId[Foreign key column] from Order entity set.
For reference:
http://social.msdn.microsoft.com/forums/en-US/adodotnetentityframework/thread/2823634f-9dd1-4547-93b5-17bb8a882ac2/
I was able to overcome this problem by the following steps:
right click the designer window
Select 'update model from database'
Select Add AND make sure that the 'Include foreign key columns in the model' checkbox is selected.
click on Finish...
I had set foreign keys up in the database but framework still wasn't pulling them in correctly. So I tried to add the association myself.
However, when I did this I would get a mapping error. It took me A WHILE but I figured out. What I did was set up the association using the entity toolbox association tool and then you have to double click on the association (1 to many) line and set the primary and foreign key there. Hopefully, this to help others who might have the same problem. I couldn't find the answer anywhere.
I had this problem for quite a different reason, and the message was slightly different; it didn't say "data inconsistency is possible because the corresponding conceptual side properties can be independently modified."
I have a table involved in my model with a binary column where I store image data. I only want this data returned when I need it (performance is a feature), so I split the table using a method similar to this. Later on, I added a property to that table, then updated the model from the database. The wizard added the property to both entity types that refer to the table with the added property. I had to delete it from one of them to solve the error.
I've had this happen because Entity Framework Update wizard mismapped some keys (or did not update?). As a result, some columns were mistakenly labeled as keys, while actual key columns were treated as plain columns.
The solution was to manually open EDMX file, find the entities, and update the keys.
Couldn't get any of the answer to work with EF6. The problem seems to be the framework doesn't import the foreign keys correctly as Associations. My solution was removing foreign keys from the tables, and then manually adding the associations using Entity Framework model, using the following steps: Entity Framework - Add Navigation Property Manually
For LinQ to Entities queries in EF1, my workaround for not having access to the foreign key as a property is with the following code, which does not produce a join query to the associated table:
dbContext.Table1s.FirstOrDefault(c => (int?)c.Table2.Id == null)
i.e, the generated SQL is:
...WHERE ([Extent1].[Table2Id] IS NULL)...
Solution is to allow deleting Rule = Cascade on Sql association.
Same thing as to be done on .edmx model, adding element to
association:
<Association Name="FK_Wheels_Slices">
<End Role="Wheels" Type= "your tipe here" Multiplicity="1">
<OnDelete Action="Cascade" />
</End>
</Association>
I had a table already mapped in EF. I added two more tables which had foreign keys in the previously added table. I then got the 3007 error.
To fix the error I deleted all three tables from the EDMX file, and then re-added them all at once together (via "Update Model from Database..."), instead of in stages.
I checked my Error List window and noticed I had errors in the model. Fixed them and all is well
in my case I solved this error by tick (include foreign key columns in the model)
- update Model from database
- tick (include foreign key columns in the model)
- finish