Questions tagged [entity-framework-4]
A tag for ADO.NET Entity Framework 4.x, itself an object-relational mapping for the .NET framework.
entity-framework-4
7,369
questions
880
votes
29
answers
945k
views
Validation failed for one or more entities. See 'EntityValidationErrors' property for more details [duplicate]
I am having this error when seeding my database with code first approach.
Validation failed for one or more entities. See 'EntityValidationErrors' property for more details.
To be honest I don't ...
- 33.6k
802
votes
21
answers
689k
views
There is already an open DataReader associated with this Command which must be closed first
I have this query and I get the error in this function:
var accounts = from account in context.Accounts
from guranteer in account.Gurantors
select new AccountsReport
...
- 27.8k
574
votes
18
answers
555k
views
EF Migrations: Rollback last applied migration?
This looks like a really common task, but I can't find an easy way to do it.
I want to undo the last applied migration. I would have expected a simple command, like
PM> Update-Database -...
- 35.3k
427
votes
20
answers
395k
views
Introducing FOREIGN KEY constraint may cause cycles or multiple cascade paths - why?
I've been wrestling with this for a while and can't quite figure out what's happening. I have a Card entity which contains Sides (usually 2) - and both Cards and Sides have a Stage. I'm using EF ...
- 12.6k
395
votes
10
answers
423k
views
Entity Framework Timeouts
I am getting timeouts using the Entity Framework (EF) when using a function import that takes over 30 seconds to complete. I tried the following and have not been able to resolve this issue:
I added ...
- 14.9k
266
votes
27
answers
269k
views
The model backing the <Database> context has changed since the database was created
The error message :
"The model backing the 'AddressBook' context has changed since the database was created. Either manually delete/update the database, or call Database.SetInitializer with an ...
- 15.1k
252
votes
2
answers
106k
views
What effect(s) can the virtual keyword have in Entity Framework 4.1 POCO Code First?
Does the virtual keyword has an effect when used on the properties in EF Code First?. Can someone describe all of its ramifications in different situations?
For instance, I know it can control lazy ...
- 44.5k
244
votes
17
answers
334k
views
How to update only one field using Entity Framework?
Here's the table
Users
UserId
UserName
Password
EmailAddress
and the code..
public void ChangePassword(int userId, string password){
//code to update the password..
}
- 5,228
231
votes
8
answers
255k
views
The object 'DF__*' is dependent on column '*' - Changing int to double
Basically I got a table in my EF database with the following properties:
public int Id { get; set; }
public string Title { get; set; }
public string Description { get; set; }
public string Image { ...
- 3,903
220
votes
5
answers
108k
views
What's the difference(s) between .ToList(), .AsEnumerable(), AsQueryable()?
I know some differences of LINQ to Entities and LINQ to Objects which the first implements IQueryable and the second implements IEnumerable and my question scope is within EF 5.
My question is what'...
- 18.8k
190
votes
20
answers
261k
views
Entity Framework: table without primary key
I have an existing DB with which I would like to build a new app using EF4.0
Some tables do not have primary keys defined so that when I create a new Entity Data Model, I get the following message:
...
- 12.2k
183
votes
2
answers
493k
views
Entity Framework Join 3 Tables
I'm trying to join three tables but I can't understand the method...
I completed join 2 tables
var entryPoint = dbContext.tbl_EntryPoint
.Join(dbContext.tbl_Entry,
...
- 5,308
183
votes
12
answers
48k
views
Entity Framework 4 / POCO - Where to start? [closed]
I've been programming for a while and have used LINQ-To-SQL and LINQ-To-Entities before (although when using entities it has been on a Entity/Table 1-1 relationship - ie not much different than L2SQL)
...
- 26.6k
178
votes
4
answers
165k
views
How to include a child object's child object in Entity Framework 5
I am using Entity Framework 5 code first and ASP.NET MVC 3.
I am struggling to get a child object's child object to populate. Below are my classes..
Application class;
public class Application
{
...
- 25.9k
171
votes
12
answers
96k
views
The specified named connection is either not found in the configuration, not intended to be used with the EntityClient provider, or not valid
I have a one entity framework object and when I add it to my project, the connectionstring
is added to app.config in the connectionstring section, but when I want to create new entitycontext and use ...
- 1,731
145
votes
8
answers
81k
views
How to make Entity Framework Data Context Readonly
I need to expose an Entity Framework Data Context to 3rd party plugins. The purpose is to allow these plugins to fetch data only and not to let them issue inserts, updates or deletes or any other ...
- 4,828
141
votes
18
answers
150k
views
Entity Framework - Invalid Column Name '*_ID"
I've narrowed this down to some issue between Code First and Database first EF, but I'm not sure how to fix it. I'll try to be as clear as I can, but I honestly am missing some of the understanding ...
- 4,812
135
votes
6
answers
93k
views
Entity Framework 4 Single() vs First() vs FirstOrDefault()
I'm having a devil of a time finding a comparison of the different ways to query for a single item, and when to use each.
Does anyone have a link that compares all these, or a quick explanation as to ...
- 3,842
135
votes
5
answers
97k
views
Entity Framework 4 - AddObject vs Attach
I have been working with Entity Framework 4 recently, and am slightly confused as to when to use ObjectSet.Attach, and ObjectSet.AddObject.
From my understanding:
Use "Attach" when an Entity already ...
- 72.8k
132
votes
9
answers
93k
views
LINQ to Entities case sensitive comparison
This isn't a case-sensitive comparison in LINQ to Entities:
Thingies.First(t => t.Name == "ThingamaBob");
How can I achieve case sensitive comparison with LINQ to Entities?
- 46.2k
130
votes
5
answers
130k
views
How should I edit an Entity Framework connection string?
I recently had to edit my app.config file to change the connection string for an Entity Framework data model (.edmx file). But I'd like to know: Is there a way to edit the EF connection string using ...
- 4,674
128
votes
6
answers
72k
views
EF Code First: How do I see 'EntityValidationErrors' property from the nuget package console?
I'm at a loss for this:
I've defined my classes for a entity framework (4.1.3) code first approach. Everything was fine (I was creating the tables etc.) until I started to Seed.
Now when I do the
...
- 1,605
121
votes
2
answers
72k
views
Entity Framework - Add Navigation Property Manually
I generated an Entity Framework Model (4.0) from my database. I did not design the database and do not have any control over the schema, but there are a few tables that do not have foreign key ...
- 32.9k
118
votes
13
answers
140k
views
Entity framework self referencing loop detected [duplicate]
I have a strange error. I'm experimenting with a .NET 4.5 Web API, Entity Framework and MS SQL Server. I've already created the database and set up the correct primary and foreign keys and ...
- 2,975
118
votes
10
answers
101k
views
The object cannot be deleted because it was not found in the ObjectStateManager
I am getting this error "The object cannot be deleted because it was not found in the ObjectStateManager."
My code is:
protected MyEntities sqlEntities;
public virtual void Delete(TEntity ...
- 3,976
113
votes
5
answers
28k
views
How do I find a specific table in my EDMX model quickly?
I was wondering if anyone knows a quicker way to find a table in the EDMX model than just scrolling through the diagram and looking for the thing. Our database has around 50 tables in it and when I'm ...
- 1,451
113
votes
17
answers
155k
views
Why am I getting this error: No mapping specified for the following EntitySet/AssociationSet - Entity1?
I'm using Entity Framework 4 with the Model First approach.
I started the project, designed the entities and generated the database. Everything worked fine.
Then I needed to go back and add another ...
- 58.5k
111
votes
5
answers
39k
views
Update relationships when saving changes of EF4 POCO objects
Entity Framework 4, POCO objects and ASP.Net MVC2. I have a many to many relationship, lets say between BlogPost and Tag entities. This means that in my T4 generated POCO BlogPost class I have:
...
- 7,471
110
votes
15
answers
90k
views
A dependent property in a ReferentialConstraint is mapped to a store-generated column
I get this error when writing to the database:
A dependent property in a ReferentialConstraint is mapped to a
store-generated column. Column: 'PaymentId'.
public bool PayForItem(int terminalId, ...
- 3,198
99
votes
7
answers
90k
views
How should I remove all elements in a DbSet?
What's the best way to remove all elements in a System.Data.Entity.DbSet, with Entity Framework 4.3?
- 67.4k
93
votes
3
answers
89k
views
Using Include in Entity Framework 4 with lambda expressions
I've seen many articles about how to overcome this matter, all related to CTP4, Or adding my own extension methods.
Is there an "official" EF4 included way to use lambda expressions inside include (...
- 14.9k
88
votes
4
answers
79k
views
EF Including Other Entities (Generic Repository pattern)
I am using the Generic Repository pattern on top of Entity Framework Code First. Everything was working fine until I needed to include more entities in a query. I got to include one entity ...
- 8,206
87
votes
16
answers
98k
views
The mapping of CLR type to EDM type is ambiguous with EF 6 & 5?
Please any one can help me to fix this error?
Schema specified is not valid. Errors:
The mapping of CLR type to EDM type is ambiguous because multiple CLR types match the EDM type 'City_DAL'. ...
- 1,038
87
votes
5
answers
11k
views
Reducing Repositories to Aggregate Roots
I currently have a repository for just about every table in the database and would like to further align myself with DDD by reducing them to aggregate roots only.
Let’s assume that I have the ...
- 6,002
85
votes
7
answers
142k
views
The specified type member is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported
var result =
(from bd in context.tblBasicDetails
from pd in context.tblPersonalDetails.Where(x => x.UserId == bd.UserId).DefaultIfEmpty()
from opd in context.tblOtherPersonalDetails....
- 883
82
votes
3
answers
33k
views
Check if there are any pending changes to be saved
Is there a way to find out whether there are unsaved changes in my entity context, in the Entity Framework?
- 24k
81
votes
8
answers
51k
views
Why does the Contains() operator degrade Entity Framework's performance so dramatically?
UPDATE 3: According to this announcement, this has been addressed by the EF team in EF6 alpha 2.
UPDATE 2: I've created a suggestion to fix this problem. To vote for it, go here.
Consider a SQL ...
- 7,643
80
votes
4
answers
57k
views
Better way to query a page of data and get total count in entity framework 4.1?
Currently when I need to run a query that will be used w/ paging I do it something like this:
//Setup query (Typically much more complex)
var q = ctx.People.Where(p=>p.Name.StartsWith("A"));
//...
- 6,849
79
votes
10
answers
119k
views
How to set CommandTimeout for DbContext?
I am looking a way to set CommandTimeout for DbContext. After searching I found the way by casting DbContext into ObjectContext and setting value for CommandTimeout property of objectContext.
var ...
- 4,505
75
votes
4
answers
120k
views
The result of a query cannot be enumerated more than once
I am using the entity framework (ef) and am getting the following error:
"The result of a query cannot be enumerated more than once.".
I have a repository class which contains the ef data context....
- 14.9k
74
votes
7
answers
240k
views
LEFT JOIN in LINQ to entities?
I'm trying out LINQ to entities.
I have a problem with the following:
I want it to do this:
SELECT
T_Benutzer.BE_User
,T_Benutzer_Benutzergruppen.BEBG_BE
FROM T_Benutzer
LEFT JOIN ...
- 80.9k
73
votes
6
answers
41k
views
what is the most reasonable way to find out if entity is attached to dbContext or not?
when i try to attach entity to context i get an exception
An object with the same key already
exists in the ObjectStateManager. The
ObjectStateManager cannot track
multiple objects with the ...
- 4,894
72
votes
16
answers
54k
views
EF4 - The selected stored procedure returns no columns
I have query in a stored procedure that calls some linked servers with some dynamic SQL. I understand that EF doesn't like that, so I specifically listed all the columns that would be returned. Yet, ...
- 4,391
72
votes
8
answers
64k
views
Entity Framework 4 mapping fragment error when adding new entity scalar
I have an Entity Framework 4 model-first design. I create a first draft of my model in the designer and all was well. I compiled, generated database, etc.
Later on I tried to add a string scalar (...
- 6,284
70
votes
1
answer
53k
views
How to include ampersand in connection string?
I'm using Entity Framework 4 for a simple app and would like to bake my connection credentials into the following connection string:
<connectionStrings>
<add name="MyEntities"
...
- 927
67
votes
1
answer
25k
views
Entity Framework mergeoption notracking bad performance
I have a strange behavior trying to execute a query declaring ObjectQuery MergeOption to "NoTracking", in this case entity framework should not attach any entity and not create the relative ...
- 1,864
66
votes
15
answers
59k
views
Entity Framework Code First Fluent Api: Adding Indexes to columns
I'm running EF 4.2 CF and want to create indexes on certain columns in my POCO objects.
As an example lets say we have this employee class:
public class Employee
{
public int EmployeeID { get; set;...
- 5,160
62
votes
5
answers
82k
views
Disable lazy loading by default in Entity Framework 4
It seems that lazy loading is enabled by default in EF4. At least, in my project, I can see that the value of
dataContext.ContextOptions.LazyLoadingEnabled
is true by default. I don't want lazy ...
- 41.5k
61
votes
8
answers
56k
views
How to specify database name in Code First?
How do I tell EF what to name the database and where to put it?
If there is no connection string in the Web.Config, it tries to put it in the local SQLEXPRESS Server, but I want to put it out on a ...
- 15.7k
61
votes
13
answers
106k
views
Entity Framework Code First AddOrUpdate method insert Duplicate values
I have simple entity:
public class Hall
{
[Key]
public int Id {get; set;}
public string Name [get; set;}
}
Then in the Seed method I use AddOrUpdate to populate table:
var hall1 = new ...
- 2,417