实体框架v4 - 无法定义两个对象之间的关系，因为它们附加到不同的ObjectContext对象

Question

This my first question on SO, although I have been using it as a resource for a long time.

First things first, I know there are a lot of questions on this topic and I think I have tried all the various solutions to no avail but it maybe I am missing something fundamental.

I am using EF4 on an asp.net MVC web application, not sure there is anything else you need to know but shout if so.

So far as I can tell I am only using one context "db" and I am not using "using" statements so I can't see that the context is being disposed of, at least not on purpose but yet I keep hitting the same error above.

The situation is this I have an action result that creates a batch of entries "ReportSections" connected to the main model "Report" based on the "Claims" which are connected to the Report through a ClaimGroup (see below).

My (simplified) classes therefore look like this;

public partial class Claim
{
    public Claim()
    {
        this.ReportSections = new HashSet<ReportSection>();
        this.Reports = new HashSet<Reports>();
    }

    public int id {get; set;}
    //other stuff

    public virtual ICollection<Reports> Reports {get; set;}
    public virtual ICollection<ReportSections> ReportSections {get; set;}
}

public partial class ClaimGroup
{
    public ClaimGroup()
    {
        this.Claims = new HashSet<Claims>();
    }

    public int id {get; set;}
    //other stuff

    public virtual ICollection<Claims> Claims {get; set;}
    public virtual ICollection<ReportSections> ReportSections {get; set;}
}

public partial class Report
{
    public Report()
    {
        this.ReportSections = new HashSet<ReportSection>();
    }

    public int id {get; set;}
    public int ClaimGroupId {get; set;}
    //other stuff

    public virtual ICollection<ReportSections> ReportSections {get; set;}
    public virtual ClaimGroup ClaimGroup {get; set;}
}

public partial class ReportSection
{
    public int id {get; set;}
    public int ClaimId {get; set;}
    public int ReportId {get; set;}
    public int Position {get; set;}
    //other stuff

    public virtual Report Report {get; set;}
    public virtual Claim Claim {get; set;}
}

[For the avoidance of doubt I am happy that the many-to-many relationship between Claims and ClaimGroups is working ok as it functions in other areas of the site.]

My Controller then has the following;

public ActionResult BuildSections(int id)
{
    Report r = db.Reports.Find(id);
    int i = 0;
    foreach(Claim c in r.ClaimGroup.Claims)
    {
        r.ReportSections.Add(new ReportSection { Claim = c, Position = i});
        i++;
    }
    db.SaveChanges();
}

It is really irritating as it doesn't seem complex but I am clearly doing something wrong.

Thanks in advance.

Sy

EDIT

The error triggers on saving back to the database so in the example here it is on

db.SaveChanges();  

However, in my various attempts to find a solution I have also tried

db.ReportSections.Add(new ReportSection {...}); 

and there the error occurred on that line.

Answer 1

Thank you to those who took the time to give me some pointers. I found the issue and thought I would post it in case it helps anyone else who makes such a school boy error.

My Claim class was made up of two partial classes in one there were some calculated fields and one of these used another context. It was that which the error was referring to not anything in the ActionResult above but of course it couldn't resolve the two when it came to saving the changes.

Thanks again

Sy