C#uses Objects Comparator for object comparison

introduced

Objects Comparer是用于对象比较的工具，C#常见的数据结构都是可以用这个三方库进行对比，比较复杂的对象也是可以比较的。

简而言之，Objects Comparer 是一个对象到对象的比较器，它允许逐个成员递归得比较对象，并为某些属性、字段或类型定义自定义比较规则。

installation

nuget 搜索ObjectsComparer：

use

First we define a simple class:

public class UserInfomation
{
    public string Name { get; set; }
    public int Age { get; set; }
    public string Sex { get; set; }
}

实例化两个UserInfomation对象并赋不同的值，再实例化 ObjectsComparer.Comparer比较器：

var comparer1 = new ObjectsComparer.Comparer<UserInfomation>();

然后我们将实例化的两个对象传入到 ObjectsComparer.Comparer 方法中：

IEnumerable<Difference> differences1;
var isEqual1 = comparer1.Compare(userInfomationOld, userInfomationNew, out differences1);

Then we use the return values to determine whether the objects are consistent. If they are inconsistent, we can get inconsistent values through differences1.

Looking at the output, you can see that the values of the age attribute of the two instanced objects are different:

那我们再试试List<T>类型的:

List<UserInfomation> lstUserInfomationsOld=new List<UserInfomation>();
for (int i = 0; i < 3; i++)
{
    UserInfomation user=new UserInfomation();
    user.Name = "张三";
    user.Age = 30;
    user.Sex = "男";
    lstUserInfomationsOld.Add(user);
}
List<UserInfomation> lstUserInfomationsNew = new List<UserInfomation>();
for (int i = 0; i < 2; i++)
{
    UserInfomation user = new UserInfomation();
    user.Name = "李四";
    user.Age = 30;
    user.Sex = "男";
    lstUserInfomationsNew.Add(user);
}


var comparer = new ObjectsComparer.Comparer<List<UserInfomation>>();
IEnumerable<Difference> differences;
var isEqual = comparer.Compare(lstUserInfomationsNew, lstUserInfomationsOld, out differences);
string differencesMsg = string.Join(Environment.NewLine, differences);
Console.WriteLine(differencesMsg);

Looking at the output, you can see that it is a problem with inconsistent quantities:

application scenarios

Anyone who has done. NET client development knows that we can't avoid editing data when maintaining some basic data!

Sometimes we open the edit page and the data has not been actually modified. Then we click the Save button to compare whether the data has been modified one by one, or we can directly use brute force without verifying whether the data has been modified, and directly call the update interface.

Then our Objects Comparator comes in handy. We first encapsulate a BaseForm, and then encapsulate a comparison method in the base class control:

protected Result ComPare<T>(T t, T s)
{
    Result result =new Result();
    var comparer = new ObjectsComparer.Comparer<T>();
    IEnumerable<Difference> differences;
    bool isEqual = comparer.Compare(t, s, out differences);
    result.IsEqual = isEqual;
    if (!isEqual)
    {
        string differencesMsg = string.Join(Environment.NewLine, differences);
        result.Msg=differencesMsg;
    }
    return result;
}

public class Result
{
    public bool IsEqual { get; set; }
    public string Msg { get; set; }
}

When we open the edit page, we will load the data of the current page. At this time, we can get the data before editing and set it as a global variable. Then when saving, we can get the edited object. At this time, we can call the base class's comparison method.

Get whether the value between the two objects has changed. If there is no change, we will give hints such as "The data has not been modified. Do you want to close the form":

public partial class MainFrm : BaseForm
{
    Test _testOld;
    public MainFrm()
    {
        InitializeComponent();
        _testOld = LoadData();
        txtName.Text= _testOld.Name;
        txtAge.Text = _testOld.Age.ToString();
        txtSex.Text = _testOld.Sex;
    }
    private Test LoadData()
    {
        Test test = new Test();
        test.Name = "张三";
        test.Age = 30;
        test.Sex = "男";
        return test;


    }


    private void uiButton1_Click(object sender, EventArgs e)
    {
        Test test=new Test();
        test.Name =txtName.Text;
        test.Age =int.Parse( txtAge.Text);
        test.Sex=txtSex.Text;
            Result result=  ComPare(_testOld, test);
        if (result.IsEqual)
        {
            MessageBox.Show("数据未修改");
            return;
        }
        //然后再写保存逻辑
        MessageBox.Show("保存成功");
    }
}
public class Test
{
    public string Name { get; set; }
    public int Age { get; set; }
    public string Sex { get; set; }
}

Of course, there are many application scenarios, I just share the scenarios I often use.

Finally, I hope you will share more useful tools with neter to jointly improve the net environment!