C# - How To Handle Foreign Keys With Entity Framework
Jan 3, 2011
how to handle foreign keys with Entity Framework, when editing or adding a new record. For example, I have a person table, which has a timezone_id linking to my timezone table.
But the model seems to not include timezone_id. I see it's a new way of doing things, but ... how do I store my record?
My method:
[code]...
I can't do u.timezone_id = timezoneid;
I only have u.timezone (which seems to be the actual entity), and u.timezoneReference, which I am not sure what to do with.
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Similar Messages:
Apr 6, 2010
Adding data into kartlar table (RehberID,KampanyaID,BrimID) is ok. But which Kart'ID created? I need to learn which Id created after adding data (RehberID,KampanyaID,BrimID) into Kartlar?
[code]...
How can I do that? I want to get data from Kartlar which data I added?
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Sep 13, 2010
1 - Is it necessary to have foreign key to obtain a Relation in Entity Framework between each entity.?
2 - I have a Language Table and many many table with a foreign key related to the language table. Is it right to add this foreign key or I should do something else ?
Ex:
Language
LangID
LangName
TableTextA
TblAID
TextInfo
LangID
TableTextB
TblBID
TextInfo
LangID
TableTextC
TblCID
TextInfo
LangID
etc ...
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Oct 18, 2010
I m try to insert record to table, its working well without foreignkey using Entity model. But i need to insert foreign key. I used the following query, its not working well via Entity model.
objFacility.FacilityCategoryReference.EntityKey =
new System.Data.EntityKey("testEntities.test",
"id", 10);
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Jul 9, 2010
Am trying to get a working enity model with foreign keys working but have run into a problem. I have imported 3 tables with content and some data.Lets call these tables geo_countries, geo_counties, geo_municipalities and the FK are:1. geo_county have a column country_id wich corresponds to country_id in geo_country 2. geo_municipality have a column county_id wich correspond to the county_id in geo_county.The problem i have is when i try to get correspondig child items with the following code i run into trouble:
[Code]....
The problem above is that 'test' generates results but not 'test2', wich never return anything. Am i not supposed to be able to do it like i do in 'test2'? I earlier tried to add a child object by replacing ToList() with Add() and that worked. But i cant seem to get anything out of it.
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Apr 5, 2010
How can I give set foreign key value field in Entity Framework. I have Kartlar entity (related from kartlar table). I need simple save method this field but, RehberID, KAmpanyaId,BirimID is foregin Key....
public static class SatisServicesUpdateTables
{
public static void SaveKartlar(int RehberID, int KampanyaID, int BrimID)
{
using (GenSatisModuleEntities genSatisKampanyaCtx = new GenSatisModuleEntities())
{
Kartlar kartlar = new Kartlar();
kartlar.RehberReference.EntityKey = new System.Data.EntityKey("genSatisKampanyaCtx.Rehber", "ID", RehberID);
kartlar.KampanyaReference.EntityKey = new System.Data.EntityKey("genSatisKampanyaCtx.Kampanya", "ID", KampanyaID);
kartlar.BirimReference.EntityKey = new System.Data.EntityKey("genSatisKampanyaCtx.Birim", "ID", BrimID);
kartlar.Notlar = "hfhfhfhfhfhfghfghfgfghk";
genSatisKampanyaCtx.AddToKartlar(kartlar);
genSatisKampanyaCtx.SaveChanges();
}
}
}
But it throws to me : ArgumentException was unhandled by user code link text
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Mar 2, 2010
I have 2 tables Departments {ID, DeptCode (PK), SubDeptCode (PK)} and Employee {ID, Name (PK), DeptID (PK & FK to ID in Deparments)}.
Both ID fields are declare as UNIQUE and incremental identity. It works fine in sql server 2000 but EF won't map the relation in my app.
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Feb 4, 2010
Using a very run-of-the-mill database, with identity int for primary keys, a Dynamic Data Entities Project (EntityFramework) displays the primary key for view and edit. When using Linq to Sql, the primary key fields are not displayed.
I would like to hide the primary keys and use Entity Framework (VS 2008, .Net 3.5 sp1).
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May 3, 2010
I developed and entity framework (.edmx) application in 4.0 in that i got all the data of my querying table and its foreign key referenced tables data also. but when i change my project to 3.5 i am unable to get the data of foreign key referenced tables data.
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Oct 12, 2010
I have a gridview displaying "registrationtype id" (FK) from the registration table. I want it to display the related name instead of the id from the registartiontype table.
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Apr 8, 2010
I'm trying to insert a new EF object containing a reference to a related table via foreign key, and cannot get the reference stored in the new object. I have two tables in a SQL Server 2008 Database:
Component Templates
PartGroups
with a Foreign Key linking them thus: ComponentTemplates:ID [0..1<->*] PartGroups:ComponentTemplateID
I have imported these tables into a .NET web application project .edmx file (using a new ADO.NET Entity Data Model), and then created a Data Service which I then reference in a Silverlight 3.0 project. The objects are available as expected in the data context called by my Silverlight app and load correctly. Now, when I try to save a reference of ComponentTemplate into a newly created PartGroup, the PartGroup object is created in the database, but the value of ComponentTemplateID in the newly created table record is NULL.
[Code]....
(Note that _ctCtrl.ComponentTemplate is a confirmed non-NULL object reference to the parent object on which PartGroup is a child)
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Jan 13, 2011
I have the following problem:- I have a Settings table which has a value column, that is incremented everytime a Job is created (I use Entity framework to add the job and to update the value increment). So, I have something like this:
[Code]....
The problem is: I have a asp.net with concurrent calls to SaveJob Method. In this code, the value is shared, and if I call SaveJob 5 times for instance, the value column is 3, because the scope is not "locking" the other transactions until It's done, and the value is shared. I want to have the following scenario: Call SaveJob 5 times;Value column in Settings table is 5;Call SaveJob 3 more times;Value Column in Settings table is 8. I tried to implement something like pessimistic concurrency in EF, but I had no success. Whats the best way to handle that without using SQL Server queries directly? (like 'lock' and 'unlock' etc)
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Dec 9, 2010
if Entity Framework 4.0 handles simple transactions automatically?
If I am only making changes to the ObjectContext, and use ObjectContext.SaveChanges(), does EF 4.0 take care of the transaction behind the scenes?
In other words, if I perform a few inserts, updates, and deletes on several different Entities and one of the fails, is everything rolled back?
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Mar 3, 2010
I am trying to get some guidance with this issue:
I have a Customer object that has two address ID fields (one for HomeAddress and one for WorkAddress)
I am loading the Address Objects by using Include="HomeAddress, WorkAddress" and then binding to the properties using the Navigation Property on the Customer Entity
Can I use just one FormView for doing the Insert/Updates and binding it to an EntityDataSource or would I have to do all the Inserting/Updating manually?
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Jun 30, 2010
I've created a new ASP.NET website. I've generated an Entity Data Model from my database and have dropped a entitydatasource and gridview onto my page and wired up the gridview to pull from the entitydatasource. Now I get columns like this: id extension prefix did_flag len ten_id restriction_class_id sfc_id name_display building_id floor room phone_id department_id
In each case where the item is named something_id this reflects a foreign key relationship in the database - and I did choose to have the EDM expose foreign key relationships. I'd like to make it so the gridview pulls in the values for these foreign keys rather than just showing the ID numbers - so, for example, department_id might have a value of "101" right now but it should pull from the department table "Marketing".
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Dec 14, 2010
Does ADO.Net Entity Framework 3.5 support Composite Foreign key/Composite primary key?
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Feb 22, 2011
I have an MVC3 with EF4 project. I have a screen for order .Order has 2 id's inside it for Billilng and Shipping AddressID .When I go and create a new order these fields render as single textboxes as Ids'Question is how can I render full address textboxes (addressline1,city,state,zip etc) do I have drop in the html markup for them? In that case while capturing the data back I willl have to go with classic way of retrieving name/value pair and then do insert into address bring back that identity and update the order record...?
Create(int customerID,FormCollection fc){}
So the main question is how can I do ModelBinding with foreign keys?
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Feb 28, 2011
I am using Access 2003 Database and I need to retrieve list of a table's foreign keys and tables they are related to in C#. I used GetSchema() function of OleDbConnection as well as OdbcConnection classes. But It just returns the name of key among few other details.
OdbcConnection con = new OdbcConnection(conStr);
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Mar 22, 2011
I am developing asp.net MVC3 application and I have following entity
This entity has composite key (CreditRegistryId and Accoubnt No are primary keys). CreditRegistryId is a foreign key as well. How can I make composite key and foreign key. I am using DbContext API from EF 4.1. I am not using edmx ( ORM designer)
[code]...
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Nov 10, 2010
I have an EF model with a table with several foreign keys. These foreign keys are managed by associations. In code, I can get a strongly typed list of objects when I access that property on the object.
When I generate a strongly typed view, all I see are the int fields. Is there a way to get ASP.NET MVC to bind to the objects that are related as well as the main object?
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Nov 7, 2010
I just came across some code that seems to encrypt database keys prior to sending them to the client (WebBrowser, Silverlight, etc).
To illustrate, suppose you have a list of students to extra-curricular activities, and a relationship defined between them. Every time the data is written out to the ASPX page, the studentID and activityID is encrypted. Every time a write, or modify is made, this value is sent back to the server, decrypted, and saved to the database.
What could be the reasons to expose data this way? Is this a normal practice?
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Mar 21, 2011
I am having trouble with foreign keys Dynamic Data and entity framework 4.0. It feels like there is a problem with the entity association but I am not sure. I have multiple fields representing the foreign key on the insert page.
When I try and insert data I get an error A dependent property in a ReferentialConstraint is mapped to a store-generated column.
Column: 'CommentId'
My data is a very basic one to many relationship, the foreign key in question is BookId in the Comment Table.
[code]...
When I let the scaffolding do its thing, I get multiple fields representing the foreign key.
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Nov 4, 2010
I have the following tables in my database which are as given under:
[code]...
My requirement is instead of getting the PromotionID values displayed for columns CustomerPromotionDiscountID & EmployeePromotionDiscountID, it should display the respective DiscountAmount. Which is not happenning for some reason.
I somehow found a workaround where if i define the datatype for columns CustomerPromotionDiscountID and EmployeePromotionDiscountID as nchar or nvarchar, it displays the DiscountAmount.
Wanted to know if there is any better way of doing this without changing the datatype for my columns?
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Dec 15, 2010
i'll make a simple website. in my website i have two kind of products to sell
1. Projects
2. Documents
These Tables are available in my database :
[code]...
now i will make an order table. should i make differentt order table?
or i could save order information of both tables in one table?
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Apr 20, 2010
If i create all of the foreign keys in my sql database and I create a linq to sql item in my project the linqs show on the diagram.
Does this mean that i dont need to create joins in my linq query in my c# code? so i mean my quesry would look something like this
[Code]....
instead of
[Code]....
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