I am using Entity Framework database-first model. I have 2 tables that are referenced by a link table.
For example:
When I update my edmx file from my database this creates the expected model:
Now what I want to do is delete an entry from the Product_User table without deleting the referenced entry in either of the related tables (Product or User).
I've tried both of these statements (together and separately) but neither seems to have any effect:
user.Products.Clear();
foreach (var product in products)
{
product.User = null;
}
Is what I'm trying to do possible with the model the way I have it now? And if so what am I doing wrong?
I noticed I can do what I'm trying to do if I add the link table explicitly to the model but I'm trying to avoid that.
Any help would be much appreciated. Thanks.
Your seconde way to go (with a loop) seems more like the correct way.
Instead of = null try to use the .Remove() function. I guess the remove function only remove the link between the two entity, not the entities related.
See this answer : Removing many to many entity Framework
I have a SQL server db ( with tables etc) and ive installed ef6 in order to use async stuff ( p.s. im new to ef).
So I added this :
played with the wizard and created a valid edmx files.
My db name is DUMP so it added Dumpentities suffix :'
so now i can do :
de = new DumpEntities1();
var data=de.AgeGroups.ToList()
But why don't I Have DbContext ? like I see in many places ?
Is xxxEntityes is a replacement for DbContext ?
cause it seems i can do all actions with xxEntites ...
edit
Ive searched "dbcontext" in my solution and apprently i do have it :
So what is going on here?
does using xxxEntiyies is the new way ?( and not doing xxxContext = new xxxContext()...even if I wanted - I dont have it...)
You should not use DbContext directly (that will not make sense) in Entity Framework. Instead you use your own custom context - class inherited from DbContext which holds sets specific to your application. When you use database first approach this custom entity class will be generated based on edmx file data, which in his turn will be generated based on database schema.
Regarding to naming... its not obvious but custom context which will be generated, will have same name as connection string name when you are creating edmx file:
Actually this will be default name for Entity Container of your conceptual entity model. If you will open edmx file in designer and take a look on its properties, you will see:
If you will change this name, context will be re-generated with name you have provided.
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 getting a weird EF4 "Entity Framework v4" error when I do a select on the context:
Schema specified is not valid. Errors:
The relationship 'AnalyzerConfigurationModel.FK_AnalyzerMetadataParameters_AnalyzerMetadata' was not loaded because the type 'AnalyzerConfigurationModel.AnalyzerMetadataParameter' is not available.
The query to generate the error is:
Using context As New AnalyzerConfigurationEntities
Dim EFAnalyzerConfiguration = (From P In context.AnalyzerConfigurations
Where P.Name = analyzerConfigurationName).FirstOrDefault
End Using
The schema is show below.
I've checked the connection strings, multiple times, its not that. Everything looks fine. I'm not sure if the XML that gets generated from this schema is off or not. But looked there too and don't see anything off or different from other properties. Has anyone run into this one before?
I found that if I expanded the EDMX file in solution explorer (VS 2012) and right clicked on each .tt file and selected Run Custom Tool also fixed the issue. This might be easier than de
Also make sure you're referencing project has the EntityFramework installed otherwise the dependent code will get this error.
https://www.nuget.org/packages/EntityFramework
Let me explain this:
The problem is because the system did not find consistency of the columns in database, the entities in the .edmx file and the model class and also the use of the same in the controller class.
So follow the following steps to fix this up:
Go to the database, check all the column names and properties.
Confirm them with the class diagram in the.edmx file. Right-click on the class in which you are getting the error, and select update option for the class. Select the Refresh tab in dialogue (if there is no new column added. if new column is added, you can select the add tab.) and select the relevant objects. Generally they are tables. So select them and finish.
Next check the names in the model class and the controller class.
This should be the solution. If not, let me know.
Are you using the SelfTracking Entity T4 template? I had this issue and found out the T4 template was not re-generating my entities after I had changed the Entity model in the Entity Designer. Try to right click the T4 Template and click "Run custom tool", and see if that helps.
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