entity-framework

问题 I am trying to implement a simple self referencing relationship with EF 6.1.2 Code First. public class Branch { [Key] public int Id { get; set; } [Required] public string Name { get; set; } public int? ParentId { get; set; } [ForeignKey("ParentId")] public virtual Branch Parent { get; set; } public ICollection<Branch> Children { get; set; } // direct successors } In my application I have exactly one root branch. And except for this single root branch, every branch has exactly one parent (the

问题 How do I register a Firebird data provider to use it with Entity Framework? What should I do to make it appear in the Entity Data Model Wizard/Choose Data Source window? I expect it to appear in the Data sources: or Data provider: lists. Is it possible? Or I need to configure this connection another way? PS: The provider I'm trying to use is the FirebirdClient 2.5 回答1: You have to install DDEX Provider for Visual Studio http://www.firebirdsql.org/index.php?op=files&id=netprovider http://web

问题 How do I register a Firebird data provider to use it with Entity Framework? What should I do to make it appear in the Entity Data Model Wizard/Choose Data Source window? I expect it to appear in the Data sources: or Data provider: lists. Is it possible? Or I need to configure this connection another way? PS: The provider I'm trying to use is the FirebirdClient 2.5 回答1: You have to install DDEX Provider for Visual Studio http://www.firebirdsql.org/index.php?op=files&id=netprovider http://web

问题 I'm trying to use EF6 code first + MySql with migrations, but I'm stuck with this error during add-migration : The underlying provider does not support the type 'nvarchar(max)' It thus seems EF is trying to use SQLServer types for MySql, even if I have changed the default connection factory in my config. I can find a lot of issues with the same error message but none of them seems up to date or to suggest something I did not already try. Here are my steps for enabling migrations in a DAL dll

问题 I'm trying to use EF6 code first + MySql with migrations, but I'm stuck with this error during add-migration : The underlying provider does not support the type 'nvarchar(max)' It thus seems EF is trying to use SQLServer types for MySql, even if I have changed the default connection factory in my config. I can find a lot of issues with the same error message but none of them seems up to date or to suggest something I did not already try. Here are my steps for enabling migrations in a DAL dll

问题 I have a simple Oracle stored procedure that gets three parameters passed in, and has one output parameter: CREATE OR REPLACE PROCEDURE RA.RA_REGISTERASSET ( INPROJECTNAME IN VARCHAR2 ,INCOUNTRYCODE IN VARCHAR2 ,INLOCATION IN VARCHAR2 ,OUTASSETREGISTERED OUT VARCHAR2 ) AS BEGIN SELECT INPROJECTNAME || ', ' || INLOCATION || ', ' || INCOUNTRYCODE INTO OUTASSETREGISTERED FROM DUAL; END RA_REGISTERASSET; I am trying to use Entity Framework 6.1 to get back the OutAssetRegistered value, however, I

问题 In the LINQ statement below, I want to select people with an exam date in 2010. The exam date is stored as a datetime as the actual date and time is used in other applications. What is the most elegant, easiest, best way to compare the exzam date to only '2010'. Or, should I just compare, using >=, the exam date to 1/1/2010? var active = dc.People.Where(x => x.exam >= 2010) .Select(x => new {x.ContactID, x.FirstName, x.LastName}) ); x.MostRecent == DateTime.Parse("1/1/2010").Year EDIT #1 I

问题 In the LINQ statement below, I want to select people with an exam date in 2010. The exam date is stored as a datetime as the actual date and time is used in other applications. What is the most elegant, easiest, best way to compare the exzam date to only '2010'. Or, should I just compare, using >=, the exam date to 1/1/2010? var active = dc.People.Where(x => x.exam >= 2010) .Select(x => new {x.ContactID, x.FirstName, x.LastName}) ); x.MostRecent == DateTime.Parse("1/1/2010").Year EDIT #1 I

问题 What might be the error? I looked at similar problems, downgrading the version to 2.0 is workaround but this is not true DAL.dll <ItemGroup> <PackageReference Include="Microsoft.EntityFrameworkCore" Version="3.1.4" /> <PackageReference Include="Microsoft.EntityFrameworkCore.Proxies" Version="3.1.4" /> <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="3.1.4" /> </ItemGroup> UIWEBAPP.dll <ItemGroup> <PackageReference Include="CKEditor" Version="3.6.4" />

问题 I have a table to save phone numbers for a contact. Within the table I have phone restrictions to tie to each phone number. The phone restrictions are stored as enums, but they can have multiple phone restrictions. When I try and create a migration I get the error The property 'PhoneNumber.Restrictions' could not be mapped, because it is of type 'ICollection' which is not a supported primitive type or a valid entity type. Either explicitly map this property, or ignore it using the '[NotMapped