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
Entity framwork made a entity for each of my tables except for one, and I'm not sure why. I select it when i generate it from the database.
Here is my entity framework diagram, and the diagram in SQL:
http://imgur.com/a/zY17T
Notice how RecipeMeal is missing from entity framework. Does anyone have an idea why this might be happening?
RecipeMeal is supposed to store if a recipe is breakfast, lunch etc. It's not a column of Recipes because a recipe could be a lunch OR dinner recipe, as an example.
I am using EF 5.0
Thanks.
Entity Framework has built-in support for many-to-many relationships.
The table is exposed through the two ICollection<T> properties in Meal and Recipe.
I also found that if your table doesn't have a primary key it will also get skipped. One of my tables was just a summary table and didn't really need a primary key and it wouldn't be included in the reverse engineer. As soon as I added a primary key it was picked up.
I'm giving EF Model first a go. I'm using EF 4.1
Pretty much followed this article
I've set PluraliseNewObjects to False on the Model and also in Options->Database Tools ->O/R Designer set Pluralization of names to false.
Neither have any effect - when I generate a new schema from the model the table names are always pluralised - is it possible to disable this?
OK - I've found one way to achieve what I want - but it's a pretty daft route.
Generated db with the plural names (interesting that it only pluralised the tables mapping to types - not the auto-generated linking tables for many to many joins).
Manually renamed the tables in the database
Deleted Model from the project and recreated based on existing database schema (the one I've just renamed).
Model is now correctly mapped to singularly names tables.
I'll wait and see if anyone comes up with a more sensible way of achieving this....
The names of the tables in the generated DDL seem to match the "Entity Set Name" values (different than the "Entity Name"). If you singularize the Entity Set Names, the table names in the DDL are singularized as well.
This will have the possibly undesired effect of singularizing the EntitySet property names in your code, though. Instead of:
myDatabase
.Products
.Where...
.Select...
your code will look like:
myDatabase
.Product
.Where...
.Select...
may or may not be an issue
I'm encountering some problems importing my DB on Entity Framework. Some relationship between tables returns me some other entities without any primary key.. For my application I need to have a PK for every table.
Is there any way to say something like:
MyEntityCollection.SetKey("ColumnName")
Or something like that?
Thank you very much!
Take a look here, i discuss this in this answer,
EF4 Unknown Column In Field List
http://xhalent.wordpress.com/2011/01/21/configuring-entity-framework-4-codefirst/ has some detail around the two ways in EF4 of specifying a FK
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