当我尝试更新实体时，EF6引发EntityValidationErrors异常

Question

I have a problem when I update entity in EF6. The code looks like this:

public PICCOSSourceCost GetCOSSourceCost(int sourceCostID)
{
    return ERPContext.PICCOSSourceCost.Where(sc => sc.ID == sourceCostID && !sc.Deleted).FirstOrDefault();
}
public PICCOSSourceCost UpdateCOSSourceCost(PICCOSSourceCost sourceCost, bool saveChanges = true)
{
    var sc = GetCOSSourceCost(sourceCost.ID);
    if (sc == null)
    {
        throw new PICObjectNotFoundException<PICCOSSourceCost>(sourceCost, new List<string>()
        {
            nameof(PICCOSSourceCost.PICCOSSourceID),
            nameof(PICCOSSourceCost.PICCOSPriceTypeID),
            nameof(PICCOSSourceCost.Price),
            nameof(PICCOSSourceCost.EffectiveDate)
        });
    }

    sc.PICCOSSourceID = sourceCost.PICCOSSourceID;
    sc.PICCOSPriceTypeID = sourceCost.PICCOSPriceTypeID;
    sc.Price = sourceCost.Price;
    sc.EffectiveDate = sourceCost.EffectiveDate;
    sc.Deleted = sourceCost.Deleted;
    sc.CreatedBy = sourceCost.CreatedBy;
    sc.CreatedDate = sourceCost.CreatedDate;
    sc.LastModifiedBy = sourceCost.LastModifiedBy;
    sc.LastModifiedDate = sourceCost.LastModifiedDate;

    if (saveChanges) ERPContext.SaveChanges();

    return sc;
}

As you can see that the "GetCOSSourceCost" method get entity from EF. And the first parameter "sourceCost" in the "UpdateCOSSourceCost" method is passed in from FrontEnd, which is also got from EF6 . When I debug the code, there is an "System.Data.Entity.Validation.DbEntityValidationException" occurred. I don't know why. I think that it should be okay because I just get an entity object and just change its properties and save changes. Is it because there are two references to the same object? If I remove the property assignment code, the error will disappear.

Validation failed for one or more entities. See 'EntityValidationErrors' property for more details.

Do you know why it throws this exception? Please help me. Thank you so much!

Answer 1

Based on this

http://mattrandle.me/viewing-entityvalidationerrors-in-visual-studio/

You can use is a special debugger variable- $exception

To view the EntityValidationErrors collection you can use below to show watch windows

((System.Data.Entity.Validation.DbEntityValidationException)$exception).EntityValidationErrors

Answer 2

Thank you for your help so much. I have solved my issue by the following link: Validation failed for one or more entities. See 'EntityValidationErrors' property for more details For the sake of this link, I debugged and find the root cause of the entity validation error. Some required fields are set to NULL value. The code from the answer is very useful:

try
{
    // Your code...
    // Could also be before try if you know the exception occurs in SaveChanges
    context.SaveChanges();
}
catch (DbEntityValidationException e)
{
    foreach (var eve in e.EntityValidationErrors)
    {
        Console.WriteLine("Entity of type \"{0}\" in state \"{1}\" has the following validation errors:", eve.Entry.Entity.GetType().Name, eve.Entry.State);
        foreach (var ve in eve.ValidationErrors)
        {
            Console.WriteLine("- Property: \"{0}\", Error: \"{1}\"", ve.PropertyName, ve.ErrorMessage);
        }
    }
    throw;
}