Category "entity-framework"

'Nullable object must have a value.' for List in LINQ c#

In database I have next model tblWorkItem with next field: public List<xWorkItemItemFailReason> WorkItemItemFailReasons { get; set; } When I am trying

Adding a New Column to an Existing Table in Entity Framework

I have added a new column to a table in my database. The table is already defined in the existing Entity Framework model. I've been through most of the items he

Cast IQueryable<DomainModel> to IQueryable<EntityModel> for EntityFramework

I'm trying to convert an IQueryable to IQueryable to allow me to take advantage of the dynamic filtering offered by Linq in the EntityFramework context. I'm try

Why doesn't scaffolding work as expected?

I am trying to scaffold and I get the following error: There was an error running the selected code generator: 'No parameterless constructor defined for typ

How to get all DbSet from DbContext

I need to get all tables in the database using EF. I need them to go table by table and extract certain information from each. Any idea how?

Entity Migration. Could not drop constraint. See previous errors

Here is the code that produce this error. I've tried solution for renaming the AddForeignKey but the error is same. 'PK_dbo.Item' is not a constraint. Co

How to Bulk Update records in Entity Framework?

I am trying to bulk update records using Entity Framework. I have tried Entity Framework.Extensions Update method. The Update method is able to bulk update for

scaffold-DbContext , command results in exception: System.Reflection.TargetInvocationException

When attempted to run a scaffold command I am now receieving the exception noted below. It may be important to note that this stopped working all of a sudden. C

Entity type ‘Business_attrib2object’ has composite primary key defined with data annotations. To set composite primary key, use fluent API

I set composite primary key using fluent API, it is still an error, when I'm trying to create ClassesController (MVC Controller with Views Using Entity Framewor

.Error CS1061 'Task<IEnumerable>' does not contain a definition for 'Where' and no accessible extension method 'Where'

My generic repository is as follows ( I have similar in synchronious and it works) public virtual async Task<IEnumerable<TEntity>> GetAsyn( Expr

Entity Framework Core multiple connection strings on same DBContext?

I have an Asp.Net Core app with Entity Framework Core that I initialize as follows: services.AddDbContext<ApplicationDbContext>(options => o

Table 'tblCustomer' does not have the identity property. Cannot perform SET operation

Occurs when I try to set the identity_insert to ON in the SQL DATAMANAGEMENT STUDIO. The worst is I do not know why should I deal with this value, and I am not

Entity Framework : Value cannot be null. Parameter name: type

When I execute update-database command, it shows this error message System.ArgumentNullException: Value cannot be null. Parameter name: type at Sy

Oracle V$SESSION Machine is <ComputerName>\<ComputerName> instead of <Domain>/<ComputerName>

I've a strange behavior with oracle and it's seems it causes problem with Security Policies. When I look the V$Session table, some connection "MACHINE" are only

Get ID of item selected in ComboBox

I have a ComboBox that gets filled with items from my database. I'm trying to get the ID of the item that is selected in the ComboBox, but nothing I've tried se

Getting the result of a computed column from database into an entity

In a project using Entity Framework, say I have an entity such as [Table("MyTable")] public partial class MyTable { public string FirstName { get; set; }

Entity Framework rollback and remove bad migration

I'm using EF 6.0 for my project in C# with manual migrations and updates. I have about 5 migrations on the database, but I realised that the last migration was

Unable to update database to match the current model because there are pending changes

I have a project built in visual studio 2013 environment with the Db built using EF 5 code first. I have had my APIs working fine for a long time but all of a

Code first migration error "Implicit conversion from data type nvarchar(max) to varbinary(max) is not allowed"

I changed the data type of a field in my model from string to byte array and I got this error when I run Update-Database code first migration method. Implic

Entity Framework Core error "Column names in each table must be unique"

I have manually added the column IdCategory to my table Books, and now each time I try to run Update-Database, I get this error: fail: Microsoft.EntityFramewor

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