Get differences between 2 linq entities and associated children entities

Question

I would like to compare two LINQ entities of the same type and return a list differences between the two. I have code that compares properties and returns the differences.

(from: https://stackoverflow.com/a/5812100/2343826)

    public static void WriteChanges<T>(T obj1, T obj2, string objName, int objId, int userId)
    {
        PropertyInfo[] properties = typeof(T).GetProperties();
        StringBuilder sb = new StringBuilder();

        foreach (PropertyInfo pi in properties)
        {
            object value1 = typeof(T).GetProperty(pi.Name).GetValue(obj1, null);
            object value2 = typeof(T).GetProperty(pi.Name).GetValue(obj2, null);

            if (value1 != value2 && (value1 == null || !value1.Equals(value2)))
            {
                sb.Append(string.Format("Property {0} changed from {1} to {2}" + Environment.NewLine, pi.Name, value1, value2));
            }
        }
        Write(objName, objId, sb.ToString(), userId);
    }

Results IN:

Property oItem changed from NS.oItem to NS.oItem
Property dvPC changed from pcName1 to pcName2

Can this code be modified to determine if the property is also a LINQ entity and if so recursively check the child entity for differences?

For instance, in the example results above, NS.oItem is a child entity associated to obj1. I would like the method to iterate through the child object to compare the differences in it between obj1 and obj2

Thanks for your help

You can use that method in your Linq Expression. I couldn't figure out your problem properly. Would you provide some code please ? — lucky, Nov 15 '17 at 19:30
hi @Rainman - thanks for your willingness... I've altered my question above to be more concise. Let me know.. Thanks again! — Fraze, Nov 15 '17 at 19:55

score 0 · Answer 1 · answered Nov 15 '17 at 20:11

You can do that, but mixing templates and reflection makes it unnecessarily complex - I'd re-write this as a non-template function, it can just take two variables of type object and fail up-front if they're not of the same type. I'm not sure why you need to check whether a property "is" a LINQ entity (which doesn't really make sense - do you mean, is mapped to an Entity Framework entity? But do you need to prevent infinite recursion where an object of type A has a property of type B, which also has a property of type A. (this is not uncommon with EF entities in order to capture foreign-key relationships - and not recursing for any property with a ForeignKey annotation is probably what you want).

Get differences between 2 linq entities and associated children entities

Results IN:

1 Answers1