实体框架和局部方法

Question

in my Entity Framework model, I have that column

    [EdmScalarPropertyAttribute(EntityKeyProperty=false, IsNullable=true)]
    [DataMemberAttribute()]
    public Nullable<global::System.Boolean> CanShow
    {
        get
        {
            return _CanShow;
        }
        set
        {
            OnCanShowChanging(value);
            ReportPropertyChanging("CanShow");
            _CanShow = StructuralObject.SetValidValue(value);
            ReportPropertyChanged("CanShow");
            OnCanShowChanged();
        }
    }
    private Nullable<global::System.Boolean> _CanShow;
    partial void OnCanShowChanging(Nullable<global::System.Boolean> value);
    partial void OnCanShowChanged();

by using the partial class, I want to add some business logic in OnCanShowChanging method

to do so, I try the code:

public partial class MyTable
{
    partial void OnCanShowChanging(bool? value)
    {
        if (some_condition)
        {
            this.CanShow = value;
        }
        //else -> avoid column data change
    }
}

But I get the StackOverflowException

I'm new in that scenario (partial method with Entity Framework), how to fix it ?

Answer 1

You can't set CanShow from inside OnCanShowChanging .

The setter for CanShow calls OnCanShowChanging , which calls the setter again, which calls OnCanShowChanging again... And so on. Infinite loop until you overflow the stack.

Answer 2

Your code have a ciclic call. Whenever you assign a value to CanShow it fires the OnCanShowChanging again and again. Modify your logic and fix that recurrent call.

Answer 3

OnCanShowChanging is being called recursively when CanShow is set. a better way to deal with this might be to do something like:

    public partial class MyTable
    {
        private bool blockOnCanShowChanging = false;

        partial void OnCanShowChanging(bool? value)
        {
            if (blockOnCanShowChanging)
            {
                return; //Recursive call...just return
            }

            if (some_condition)
            {
                //Turn on bool to avoid recusive call
                blockOnCanShowChanging = true;

                this.CanShow = value;

                //reset bool to allow subsequent calls to OnCanShowChanging
                blockOnCanShowChanging = false;
            }

            //else -> avoid column data change
        }
    }