EF外键设置

Question

I have a question regarding the setup of foreign keys in entity framework 6. Our project stores data from a few other services (to have faster access to the data) and provides the users with charts and statistics depending on the stored data. For the storage of the data we´ve setup a cronjob which runs daily at about 3 AM.

Here are 2 example database models:

public class Project {
    public string Id { get; set; }
    public string Title { get; set; }
}

public class Issue {
    public string Id { get; set; }
    public string Title { get; set; }
    [ForeignKey("Project")]
    public string ProjectId { get; set; }
    [ForeignKey("ProjectId")]
    public Project Project { get; set; }
}

The problem now is for some issues we don´t save the project it depends on but we have to save the ProjectId (because at a later point it might be possible that the project exists in our database). So when I try to save this issues it tells me that I can´t save them because the project does not exist.

Is there any way I can tell entity framework that it doesn´t matter if the project exists or not? Currently I´ve just removed the ForeignKeys but this makes it very slow when I try to get the full list of issues with their projects.

Or is there any other way to read out all issues with their projects if there are no foreign keys? Currently I´m using a foreach loop to go threw each issue and then I search for the project but with more than 10.000 issues this get´s very slow.

Answer 1

The navigation property you've defined is requiring the data in the Project table in order to save an Issue . This isn't Entity Framework, this is a SQL Server foreign key constraint issue. Entity Framework is doing preliminary validation to not waste a connection that will ultimately fail. While you can turn off enforcing the foreign key constraint, there is not a good way to turn this validation off in Entity Framework

Keep in mind, having a foreign key does not mean it will help with your query's performance. It's simply a way to enforce referential integrity. I suspect that your real problem is the way you've written your query. Without seeing your query and metrics around "slow", it be hard to point you in the right direction.