How to compare properties between two objects

Question

I have two similar classes : Person , PersonDto

public class Person 
{
    public string Name { get; set; }
    public long Serial { get; set; }
    public DateTime Date1 { get; set; }
    public DateTime? Date2 { get; set; }
}

&

public class PersonDto
{
    public string Name { get; set; }
    public long Serial { get; set; }
    public DateTime Date1 { get; set; }
    public DateTime? Date2 { get; set; }
}

I have two objects of both by equal values.

    var person = new Person { Name = null , Serial = 123, Date1 = DateTime.Now.Date, Date2 = DateTime.Now.Date };
    var dto = new PersonDto { Name = "AAA", Serial = 123, Date1 = DateTime.Now.Date, Date2 = DateTime.Now.Date };

I need to check value of all properties in two classes by reflection. My final goal is defined difference value of this properties.

    IList diffProperties = new ArrayList();
    foreach (var item in person.GetType().GetProperties())
    {
        if (item.GetValue(person, null) != dto.GetType().GetProperty(item.Name).GetValue(dto, null))
            diffProperties.Add(item);
    }

I did this, but result is not satisfactory. Count of diffProperties for result was 4but count of my expect was 1.

Of course all properties can have null values.

I need to a solution generic. What must do I?

Hi dear Ehsan, I believe you are on a wrong track, having two classes with exactly same implementation is totally wrong idea, you need just one class and several (2 here) objects of it. You are checking let's say a serial with another serial which check their storage place in RAM not their real VALUE, consider that checking values is a different content in OOP. — Mahdi Tahsildari
– Mahdi Tahsildari, Commented Aug 22, 2012 at 6:30

Alexei Levenkov · Accepted Answer · 2012-08-22 06:47:01Z

12

If you want to stick with comparison via reflection you should not use != (reference equality which will fail most of comparisons for boxed results of GetProperty calls) but instead use static Object.Equals method.

Sample how to use Equals method to compare two object in your reflection code.

 if (!Object.Equals(
     item.GetValue(person, null),
     dto.GetType().GetProperty(item.Name).GetValue(dto, null)))
 { 
   diffProperties.Add(item);
 }

edited Aug 22, 2012 at 6:47

Alexei Levenkov

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answered Aug 22, 2012 at 6:14

M.Azad

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1 Comment

Alexei Levenkov Over a year ago

+1: actually changed my mind (and edited the answer) - this is exactly why OPs code was not working - != does reference comparison which pretty much always failes for boxed results of reflectin "get property", correct call to Equals does comparisions in expected way.

CarenRose · Accepted Answer · 2019-12-12 00:14:32Z

1

You may consider making the Person class implement the IComparable interface and implementing the CompareTo(Object obj) method.

edited Dec 12, 2019 at 0:14

CarenRose

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answered Aug 22, 2012 at 6:25

Kishore Borra

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Comments

Saint · Accepted Answer · 2012-08-22 06:25:59Z

0

Implement IEquatable interface

answered Aug 22, 2012 at 6:25

Saint

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Comments

Jordy van Eijk · Accepted Answer · 2012-08-22 06:26:16Z

-1

Looking at you classes not all values can be null you have a nullable long. But that said.

I also made something like this and used this website for it. Just make it so that it can accept 2 different objects. I can't share my code because of licensing sorry.

answered Aug 22, 2012 at 6:26

Jordy van Eijk

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1 Comment

Alexei Levenkov Over a year ago

-1. Please provide some information - if you want to share link - post as comment, otherwise please make sure at least summary of link's content is in the answer.

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