A Function That Compares the Properties of Two Objects

**Ashura** · Nov 17 '05, 12:19 PM

RE: A Function That Compares the Properties of Two Objects

Thats not so hard to do:

//...

PropertyInfo[] fields = thisType.GetPro perties();
foreach (PropertyInfo propInfo in fields) {

if (propInfo.Prope rtyType.IsArray ) {
object val = propInfo.GetVal ue(angel, null);

IEnumerator ie = ((System.Array) val).GetEnumera tor();
while(ie.MoveNe xt()) {
//Now we have the individual object in the array
Console.WriteLi ne(ie.Current.G etType().ToStri ng());
}
}

//...
}

**Ignacio Machin \( .NET/ C# MVP \)** · Nov 17 '05, 12:19 PM

Re: A Function That Compares the Properties of Two Objects

Hi,

Ashura's post should solve your problem, I just want to remember you that if
a property has a reference type you are comparing references ( if both
instances refers to the very same instance, not two instances with same
values).

cheers,

--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation

<orekinbck@yaho o.com.au> wrote in message
news:1131094226 .727025.317640@ g49g2000cwa.goo glegroups.com.. .[color=blue]
> Hi There
>
> I am learning about reflection so apologies if this post is vague ...
>
> I am doing some unit testing and have written a function that accepts
> two objects and tests to see if their properties are equal. It seems
> to work OK except when a object has a property that is an array.
>
> The GetValue method of the PropertyInfo class returns an object, and I
> want to convert it to an array of objects. For some reason, this
> fails:
>
> object[] objectArray = (object[])myObject;
>
> However if I know the type, then it works. For example:
>
> SecurityRoles[] rolesArray = (SecurityRoles[])object;
>
> The problem is that I don't know the type at design time ! I tried to
> do this:
>
> propInfo.Proper tyType[] objectArray =
> (propInfo.Prope rtyType[])myObject;
>
> But it did not compile (ps ... propInfo is an instance of the
> PropertyInfo class).
>
> The code listing for my function is below. I would really appreciate
> any guidance!
>
> Thanks
> Bill
>
> using System;
> using System.Reflecti on;
>
> namespace ServerTest
> {
> public static class ObjectComparer
> {
> /// <summary>
> /// This function compares any two objects properties. It will
> recursively search down through nested properties
> /// WARNING - It only compares properties that are one of the
> following string, char, short, int, long, bool, DateTime, Enum
> /// *** IT IGNORES ANY PROPERTIES THAT ARE ARRAYS ***
> /// </summary>
> /// <param name="thisType" >The type of the two objects</param>
> /// <param name="leftObjec t"></param>
> /// <param name="rightObje ct"></param>
> /// <returns>True to indicate that the objects are equal.
> False otherwise</returns>
> public static bool AreTheseObjectE qual(Type thisType, object
> leftObject, object rightObject)
> {
> if (leftObject == null && rightObject == null)
> return true;
>
> if (leftObject == null || rightObject == null)
> return false;
>
> PropertyInfo[] fields = thisType.GetPro perties();
>
> foreach (PropertyInfo propInfo in fields)
> {
> if (propInfo.Prope rtyType.IsArray )
> {
>
>
> //*************** *************** *************** *************** *************** ******
> //Property is an array, need to iterate through the
> elements and compare them
>
> //*************** *************** *************** *************** *************** ******
>
> //object lhs = propInfo.GetVal ue(leftObject, null);
> //object rhs = propInfo.GetVal ue(rightObject,
> null);
>
> ////This does not work
> //object[] lhsArray = (object[])lhs;
> //object[] rhsArray = (object[])rhs;
>
> ////If the above worked, I could then do this:
> //if (lhsArray.Lengt h != rhsArray.Length )
> // return false;
> //else
> //{
> // for (int i = 0; i < lhsArray.Length ; i++)
> // {
> // if (false ==
> AreTheseObjectE qual(propInfo.P ropertyType,
> (object)lhsArra y[i],(object)rhsArr ay[i]))
> // return false;
> // }
> //}
>
> //BUT .... If I knew the type then this would
> work:
> //STE.Model.Secur ityRoles[] secRolesLHS =
> (STE.Model.Secu rityRoles[])lhs;
> //STE.Model.Secur ityRoles[] secRolesRHS =
> (STE.Model.Secu rityRoles[])rhs;
> //But I don't know the type at run time
> }
> else
> {
> object lhs = propInfo.GetVal ue(leftObject, null);
> object rhs = propInfo.GetVal ue(rightObject, null);
>
> if (propInfo.Prope rtyType.IsEnum)
> {
> if (lhs.ToString() != rhs.ToString())
> return false;
> }
> else if (lhs is string)
> {
> if (false == rhs is string)
> return false;
> if ((string)lhs != (string)rhs)
> return false;
> }
> else if (lhs is char)
> {
> if (false == rhs is char)
> return false;
> if ((char)lhs != (char)rhs)
> return false;
> }
> else if (lhs is bool)
> {
> if (false == rhs is bool)
> return false;
> if ((bool)lhs != (bool)rhs)
> return false;
> }
> else if (lhs is short)
> {
> if (false == rhs is short)
> return false;
> if ((long)lhs != (long)rhs)
> return false;
> }
> else if (lhs is int)
> {
> if (false == rhs is int)
> return false;
> if ((int)lhs != (int)rhs)
> return false;
> }
> else if (lhs is long)
> {
> if (false == rhs is long)
> return false;
> if ((long)lhs != (long)rhs)
> return false;
> }
> else if (lhs is DateTime)
> {
> if (false == rhs is DateTime)
> return false;
> if ((DateTime)lhs != (DateTime)rhs)
> return false;
> }
> else
> {
> PropertyInfo[] nestedFields =
> propInfo.Proper tyType.GetPrope rties();
> if (nestedFields.L ength > 0)
> {
> if (false ==
> AreTheseObjectE qual(propInfo.P ropertyType,
> propInfo.GetVal ue(leftObject, null), propInfo.GetVal ue(rightObject,
> null)))
> return false;
> }
> }
> }
> }
> return true;
> }
> }
> }
>[/color]

**S. Senthil Kumar** · Nov 17 '05, 12:20 PM

Re: A Function That Compares the Properties of Two Objects

Unless of course, the reference type overloaded the equality operator.

**Ben** · Nov 17 '05, 12:21 PM

Re: A Function That Compares the Properties of Two Objects

Great !!! It appears to be working perfectly. Thanks everyone for your help.

If you are interested I have posted the complete code:

Microsoft Learn: Build with answers in reach

https://msdn.microsoft.com/newsgroups/managed/default.aspx?&lang=en&cr=US&guid=&sloc=en-us&dg=microsoft.public.dotnet.languages.csharp&p=1&tid=11ee5857-407b-4ec8-a005-583e484fb370&mid=11ee5857-407b-4ec8-a005-583e484fb370

Find official documentation, practical know-how, and expert guidance for builders working and troubleshooting in Microsoft products.

It is my first foray into reflection and recursion, so I would be interested
in any feedback

Cheers
Bill

A Function That Compares the Properties of Two Objects

A Function That Compares the Properties of Two Objects

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