违反多重性约束。 角色 &#39; <T> 关系的&#39;具有多重性1或0..1

Question

I have 1 to many relationship with in my database I am trying to update all of th objects in the collection using a generic method.

    public static void DuplicateItem<T>(T dataBaseItem, T origionalItem)
    {
        var type = origionalItem.GetType();
        var properties = type.GetProperties();
        var databasePropertyInfo = dataBaseItem.GetType();
        foreach (var origionalProperty in properties)
        {
            var n = origionalProperty.Name;
            var databaseProperty = databasePropertyInfo.GetProperty(origionalProperty.Name);
            if(IsComplex(origionalProperty.GetValue(origionalItem,null)))
                continue;

            var origionalValue = origionalProperty.GetValue(origionalItem, null);
            var t = Nullable.GetUnderlyingType(origionalProperty.PropertyType) 
                ?? origionalProperty.PropertyType;
            var saveValue = (origionalValue == null) ? null : Convert.ChangeType(origionalValue, t);
            databaseProperty.SetValue(dataBaseItem, saveValue);
        }
    }

this method works great except on collections. it will just simply add the items from originalItem.Collection to databaseItem.Colletion which is causing me to have double the amount of items that i should which is making me through this excption. What i want is to just update all of the children from databaseItem.Collection to origanalItem.Collection .

So I tried to make a change:

    public static void DuplicateItem<T>(T dataBaseItem, T origionalItem)
    {
        var type = origionalItem.GetType();
        var properties = type.GetProperties();
        var databasePropertyInfo = dataBaseItem.GetType();
        foreach (var origionalProperty in properties)
        {
            var n = origionalProperty.Name;
            var databaseProperty = databasePropertyInfo.GetProperty(origionalProperty.Name);
            if(IsComplex(origionalProperty.GetValue(origionalItem,null)))
                continue;
            if (IsCollection(origionalProperty.GetValue(origionalItem, null)))
            {
                ClearItems(databaseProperty.GetValue(dataBaseItem,null), 
                    origionalProperty.GetValue(origionalItem, null));
            }
            var origionalValue = origionalProperty.GetValue(origionalItem, null);
            var t = Nullable.GetUnderlyingType(origionalProperty.PropertyType) 
                ?? origionalProperty.PropertyType;
            var saveValue = (origionalValue == null) ? null : Convert.ChangeType(origionalValue, t);
            databaseProperty.SetValue(dataBaseItem, saveValue);
        }
    }

and ClearItems:

    private static void ClearItems(object databaseValue, object newvalue)
    {
        var l = databaseValue as IEnumerable<object>;
        var n = newvalue as IEnumerable<object>;
        if (l != null)
        {
            for (int i = 0; i < l.Count(); i++)
            {
                var dItem = l.ToList()[i];
                var nItem = n.ToList()[i];
                DuplicateItem(dItem,nItem);
            }

        }
    }

This now gives me only 3 items but i am still throwing the exception. So now my question: How can i use ClearItems<TDatabase,TOriganial> to update all items in collection and all properties in collection?

Thank you.

Answer 1

I found the solution after a day of playing with it i didn't add a continue so it was still adding the items.

public static void DuplicateItem<T>(T dataBaseItem, T origionalItem)
    {
        var type = origionalItem.GetType();
        var properties = type.GetProperties();
        var databasePropertyInfo = dataBaseItem.GetType();
        foreach (var origionalProperty in properties)
        {
            var n = origionalProperty.Name;
            var databaseProperty = databasePropertyInfo.GetProperty(origionalProperty.Name);
            if(IsComplex(origionalProperty.GetValue(origionalItem,null)))
                continue;
            if (IsCollection(origionalProperty.GetValue(origionalItem, null)))
            {
                ClearItems(databaseProperty.GetValue(dataBaseItem,null), 
                    origionalProperty.GetValue(origionalItem, null));
                continue;
            }
            var origionalValue = origionalProperty.GetValue(origionalItem, null);
            var t = Nullable.GetUnderlyingType(origionalProperty.PropertyType) 
                ?? origionalProperty.PropertyType;
            var saveValue = (origionalValue == null) ? null : Convert.ChangeType(origionalValue, t);
            databaseProperty.SetValue(dataBaseItem, saveValue);
        }
    }