entity-framework

问题 I'm using Entity Framework Core with Code First approach but recieve following error when updating the database: Introducing FOREIGN KEY constraint 'FK_AnEventUsers_Users_UserId' on table 'AnEventUsers' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints. Could not create constraint or index. See previous errors. My entities are these: public class AnEvent { public int AnEventId { get; set; } public DateTime

问题 I am trying to get data from 3 entities. Exam, Objective and Objective detail. I want to be able to select this by exam name. Here is the code I am using: var result = await db.Exams .Include(e => e.Objectives) .Include(e => e.Objectives.SelectMany(o => o.ObjectiveDetails)) .Where(e => e.Name == name) .FirstOrDefaultAsync(); This is giving me an error message when I run it saying: exceptionMessage=The Include path expression must refer to a navigation property defined on the type. Use dotted

问题 I am trying to get data from 3 entities. Exam, Objective and Objective detail. I want to be able to select this by exam name. Here is the code I am using: var result = await db.Exams .Include(e => e.Objectives) .Include(e => e.Objectives.SelectMany(o => o.ObjectiveDetails)) .Where(e => e.Name == name) .FirstOrDefaultAsync(); This is giving me an error message when I run it saying: exceptionMessage=The Include path expression must refer to a navigation property defined on the type. Use dotted

问题 Unfortunately my EF application has to call stored procedures I am unable to change. While this is not ideal I can normally get around it. However, I have a stored proc that does return anything. How does EF core deal with this? I know in previous versions you could run ExecuteNonQuery but I haven't been able to find anything similar in EF Core. I normally run my queries through a helper as such, where T is a class that maps to a return type EF can serialize to: context.Set<T>() .AsNoTracking

问题 Unfortunately my EF application has to call stored procedures I am unable to change. While this is not ideal I can normally get around it. However, I have a stored proc that does return anything. How does EF core deal with this? I know in previous versions you could run ExecuteNonQuery but I haven't been able to find anything similar in EF Core. I normally run my queries through a helper as such, where T is a class that maps to a return type EF can serialize to: context.Set<T>() .AsNoTracking

问题 I've got an object that has a key stored as a GUID as well as a friendlyID, like this: public class Job { [Key] public Guid Id { get; set; } [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int FriendlyId { get; set; } public string Description { get; set; } } However when I try to update description using my update method: public void Update(Job job, Job jobParam) { if (job == null) { throw new AppException("Job does not exist"); } //Update job properties job.Description =

问题 I've got an object that has a key stored as a GUID as well as a friendlyID, like this: public class Job { [Key] public Guid Id { get; set; } [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int FriendlyId { get; set; } public string Description { get; set; } } However when I try to update description using my update method: public void Update(Job job, Job jobParam) { if (job == null) { throw new AppException("Job does not exist"); } //Update job properties job.Description =

问题 Let's say I have a Todo model with a corresponding Todo table ( DbSet<Todo> ) in an EF-generated database. The table will store a todo item per row. Each user (in an ASP.NET Core Identity + IdentityServer app) will be associated with multiple todo items (one-to-many, a user can have multiple todo items). The way I'd do it is to add a UserId foreign key to the Todo model that represents the user that owns the todo item . How would I do that with EF Core while utilizing the classes proved by

问题 I am receiving ~300+ exceptions that are spammed in my server output labeled: Exception thrown: 'System.ArgumentException' in System.Linq.Expressions.dll The query I am using is as follows: Account account = _accountContext.Account. Include(i => i.Currency). Include(i => i.Unlocks). Include(i => i.Settings). Include(i => i.Friends). FirstOrDefault(a => a.FacebookUserID == facebookUserID); Eventually the exceptions stop generating, it shows a large query in the output window, and everything

问题 I am receiving ~300+ exceptions that are spammed in my server output labeled: Exception thrown: 'System.ArgumentException' in System.Linq.Expressions.dll The query I am using is as follows: Account account = _accountContext.Account. Include(i => i.Currency). Include(i => i.Unlocks). Include(i => i.Settings). Include(i => i.Friends). FirstOrDefault(a => a.FacebookUserID == facebookUserID); Eventually the exceptions stop generating, it shows a large query in the output window, and everything