How to ignore object properties?

Aug 30, 2013 at 6:14 PM
Edited Aug 30, 2013 at 6:24 PM
I'm trying to figure out how to ignore properties for my objects to compare.

I tried the following with no luck:
                    Configuration config = Configuration.Default;
                    config.CheckIgnoreMember(typeof (Insured).GetProperty("InsertDate"));
                    Snapshot s1 = new ObjectSnapshot(clonedObject);
                    Snapshot s2 = new ObjectSnapshot(originalPolicyTranObject);

                    CompareItem ci = new ObjectCompareItem();
                    ci.Create(s1, s2);
                    ChangeSet cs = new ChangeSet();
                    var flat = cs.Flatten();
Seems like the configuration changes are not passed to the comparer. Also I tried excluding my properties at the Snapshot level but didn't find a way to manually set the context or change it for that SnapShot object... By looking at the code it is only using defaults.

Any help appreciated.
Sep 6, 2013 at 4:44 PM
Currently returned from vacation :)

Hi adolfo - I'll have look at that in the next hours and give you a solution.
Sep 6, 2013 at 7:26 PM
Edited Sep 6, 2013 at 7:50 PM
Modifying the CheckIgnoreMember property wasn't intended, till now.
My intense was, that you can
  • compare objects respecting all properties
  • compare objects respecting selected properties (by tagging them with CompareAttribute)
  • compare objects respecting selected properties (by setting them via an external configuration file) <<< this is currently progress
But yours is an interesting approach for steering the snap shot creation and I agree, it is useful. :) Thanks adolfo1981!

I've created and solved issues 1498 ( and 1499 ( Also I've created a unit test (Project:ObjectComparer.Tests > Class:ConfigurationTest > Method:DefaultCheckIgnorePropertyTest).

Now it is possible to create a context object, set it up and pass it for snap shot creation.
The subjected unit test shows how you can modify the context and also the CheckIgnoreMember delegate.

Let's take a look at that example:

First, you've to instantiate a context object:
var myContext = Context.GetDefaultContext();
Second, you've to replace the default delegate for CheckIgnoreMember
myContext.Configuration.CheckIgnoreMember = new CheckIgnoreMemberDelegate(delegate(object o) {
var retval = true;
// ... your decisions go here ...
return retval;
myContext.Configuration.CheckIgnoreMember = new CheckIgnoreMemberDelegate(delegate(object o) {
                var ignore = false;
                // Check to ignore by name of member (field or property)
                var memberNameToCheck = string.Empty;
                if (o is PropertyInfo) {
                    memberNameToCheck = (o as PropertyInfo).Name;

                } else if (o is FieldInfo) {
                    memberNameToCheck = (o as FieldInfo).Name;

                } else if (o is string)
                    memberNameToCheck = o as string;
                ignore |= string.Equals(memberNameToCheck, "Number");

                // Check to ignore by PropertyInfo
                if (o is PropertyInfo) {
                    var pi = o as PropertyInfo;
                    ignore |= pi == typeof(Order).GetProperty("Customer");
                // Return value
                return ignore;

Third, you've to pass the context to the neccessary methods
            ss1 = new ObjectSnapshot(yourObject, myContext);
            // modify "yourObject"
            ss2 = new ObjectSnapshot(yourObject, myContext);

            ci = new ObjectCompareItem();
            ci.Create(ss1, ss2);
            cs = new ChangeSet();
Marked as answer by testy on 4/8/2014 at 4:37 PM
Sep 6, 2013 at 7:54 PM
Thanks for the quick response and fix!! I'll try it out as soon as possible. I really like your project by the way.
Sep 10, 2013 at 8:27 AM
:) cool, thanks!
Please give me your Feedback, if it fits for you.
Sep 10, 2013 at 11:34 AM
Just tried it and it works fine. Thanks again!
Sep 17, 2013 at 10:24 PM
I've tested using the configuration/context more than once (like the solution I told you) and found out, that when not creating new instances between snapshot creations all subsequent snapshots contain incomplete data. I'll fix this soon (linked issue:
May 21, 2014 at 2:36 PM

Is it possible to make Context.GetDefaultContext method public?
       internal static Context GetDefaultContext() {
When I call Context.Default it is always returning me the same Context once it creates it:
public static Context Default {
            get {
                if( _default==null )
                    _default = GetDefaultContext();

                return _default;

And I need a new context every time I call the compare.

May 22, 2014 at 9:31 PM

I think the easiest way is to create a new context-object:
May 27, 2014 at 11:45 AM
I just saw the new thread. That solution worked, thanks again for your help and quick response.