Get the differences between 2 lists

Question

I have two lists ( ListA and ListB ), the type of these lists is the same PersonInfo , the Login field is a unique key.

public class PersonInfo
{
    public string Login { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public int Age { get; set; }
    public bool Active { get; set; }
}

I'd like compare these two lists :

1. I'd like get a list of items in ListA not available in ListB

2. For the items available in both lists, I'd like get a list from ListA ( Login field is a unique key) for the item where there is a difference between the two lists.

Example : if for the Login "MyLogin" in ListA , the value of FirstName does not match with the value in ListB . The item with "MyLogin" as Login must be part of the result list.

Example : if the Age between ListA and ListB for a specific login is different, the item must be part of the result

Thanks.

Answer 1

EDIT

Try this soltuion for detail difference : Compare two objects and find the differences

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How to: Find the Set Difference Between Two Lists (LINQ)

Enumerable.Except Method (IEnumerable, IEnumerable) -Produces the set difference of two sequences by using the default equality comparer to compare values.

       double[] numbers1 = { 2.0, 2.1, 2.2, 2.3, 2.4, 2.5 };
        double[] numbers2 = { 2.2 };

        IEnumerable<double> onlyInFirstSet = numbers1.Except(numbers2);

or

//newList will include all the common data between the 2 lists
List<T> newList = list1.Intersect(list2).ToList<T>();


//differences will be the data not found 
List<T> differences = list1.RemoveAll(a => newList.Contains(a));

or

outer join to get difference

var compare1to2 = from a in 
           from b in driveList2.Where(b => b.property == a.property).DefaultIfEmpty()
                              select a;

Answer 2

To compare objects of custom data type lists, you will need to implement IEquatable in your class and override GetHashCode()

Check this MSDN Link

Your class

    public class PersonInfo : IEquatable<PersonInfo>
    {
        public string Login { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public int Age { get; set; }
        public bool Active { get; set; }

        public bool Equals(PersonInfo other)
        {
            //Check whether the compared object is null.
            if (Object.ReferenceEquals(other, null)) return false;

            //Check whether the compared object references the same data.
            if (Object.ReferenceEquals(this, other)) return true;

            //Check whether the properties are equal.
            return Login.Equals(other.Login) && FirstName.Equals(other.FirstName) && LastName.Equals(other.LastName) && Age.Equals(other.Age) && Active.Equals(other.Active);
        }

        public override int GetHashCode()
        {

            int hashLogin = Login == null ? 0 : Login.GetHashCode();

            int hashFirstName = FirstName == null ? 0 : FirstName.GetHashCode();

            int hashLastName = LastName == null ? 0 : LastName.GetHashCode();

            int hashAge = Age.GetHashCode();

            int hashActive = Active.GetHashCode();

            //Calculate the hash code.
            return (hashLogin + hashFirstName + hashLastName) ^ (hashAge + hashActive);
        }
    }

Then here is how you use it (as listed in Pranay's response)

            List<PersonInfo> ListA = new List<PersonInfo>() { new PersonInfo { Login = "1", FirstName = "James", LastName = "Watson", Active = true, Age = 21 }, new PersonInfo { Login = "2", FirstName = "Jane", LastName = "Morrison", Active = true, Age = 25 }, new PersonInfo { Login = "3", FirstName = "Kim", LastName = "John", Active = false, Age = 33 } };
            List<PersonInfo> ListB = new List<PersonInfo>() { new PersonInfo { Login = "1", FirstName = "James2222", LastName = "Watson", Active = true, Age = 21 }, new PersonInfo { Login = "3", FirstName = "Kim", LastName = "John", Active = false, Age = 33 } };

            //Get Items in ListA that are not in ListB
            List<PersonInfo> FilteredListA = ListA.Except(ListB).ToList();

            //To get the difference between ListA and FilteredListA (items from FilteredListA will be removed from ListA)
            ListA.RemoveAll(a => FilteredListA.Contains(a));

Answer 3

var list3 = list1.Except(list2).ToList(); //List3 contains what in list1 but not _list2.

Answer 4

Try this for objects comparison and loop around it for List<T>

public static void GetPropertyChanges<T>(this T oldObj, T newObj)
{
    Type type = typeof(T);
    foreach (System.Reflection.PropertyInfo pi in type.GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance))
    {
        object selfValue = type.GetProperty(pi.Name).GetValue(oldObj, null);
        object toValue = type.GetProperty(pi.Name).GetValue(newObj, null);
        if (selfValue != null && toValue != null)
        {
            if (selfValue.ToString() != toValue.ToString())
            {
                //do your code
            }
        }
    }
}

Answer 5

您可以使用LINQ中的Zip（）和Intersect（）