I have two lists and I want to compare these and update below fields using 2nd list value StudentAddressLine1,StudentAddressLine2,StudentAddressPincode,StudentAddressCity,StudentAddressState

Student Class

public class Student
    {
       
        public string StudentNumber { get; set; }
        public string StudentName { get; set; }
        public string StudentClass { get; set; }
        public string StudentPhoneNumber { get; set; }
        public string StudentEmail { get; set; }
        public string StudentFatherPhoneNumber { get; set; }
        public string StudentFatherEmail { get; set; }
        public string StudentMotherPhoneNumber { get; set; }
        public string StudentMotherEmail { get; set; }
        public string StudentAddressLine1 { get; set; }
        public string StudentAddressLine2 { get; set; }
        public string StudentAddressPincode { get; set; }
        public string StudentAddressCity { get; set; }
        public string StudentAddressState { get; set; }
        public Student SetIndex(int index)
        {
            RowNo = index;
            return this;
        }
    }

AddressFromExternalAPI Class

public class AddressFromExternalAPI
    {
        public string SNumber { get; set; }
        public string SName { get; set; }
        public string SClass { get; set; }
        public int ID { get; set; }
        public string AddressLine1 { get; set; }
        public string AddressLine1 { get; set; }
        public string Pincode { get; set; }
        public string City { get; set; }
        public string State  { get; set; }
    }

Below is my code where I use a loop and compare two lists and update the fields

public virtual IEnumerable<Student> getStudentDetails(IEnumerable<Student> students)
        {
            var studentList = new List<Student>();
            var addresslist = getStudentAddress(students)
            studens.ForEach((y, index ) =>
            {
                var rowIndex = index   1;
                foreach (var address in addresslist)
                {
                    if (rowIndex == address.ID&& y.StudentNumber == address.SNumber &&y.StudentName == address.SName &&y.StudentClass == address.SClass)
                    {
                        studentHelper.addAddress(y, ds);
                    }
                    studentList.Add(y);
                }
            });
            return studentList;
        }
            
public static void addAddress(Student student, AddressFromExternalAPI address)
        {
            student.StudentAddressLine1 = address.AddressLine1;
            student.StudentAddressLine2 = description.AddressLine2;
            student.StudentAddressPincode = description.Pincode;
            student.StudentAddressCity = description.City;
            student.StudentAddressState = description.State;
           
        }

could you please advise some other way to implement this logic instead of foreach?

Is there any other way instead of doing multiple loops?looking for a more compact solution?

CodePudding user response：

Ignoring ID, and assuming matching based on Number, Name and Class is sufficient, you can store the addresses in a Dictionary and lookup the matches:

public virtual IEnumerable<Student> getStudentDetails(IEnumerable<Student> students) {
    var addressDict = getStudentAddress(students).ToDictionary(a => (a.SNumber, a.SName, a.SClass));
    var studentList = students.ToList();

    foreach (var student in studentList) {
        if (addressDict.TryGetValue((student.StudentNumber, student.StudentName, student.StudentClass), out var address)) {
            student.StudentAddressLine1 = address.AddressLine1;
            student.StudentAddressLine2 = address.AddressLine2;
            student.StudentAddressPincode = address.Pincode;
            student.StudentAddressCity = address.City;
            student.StudentAddressState = address.State;
        }
    }

    return studentList;
}

CodePudding user response：

I tried to make it as much as possible with the information given. List<T>.ForEach(Action<T>) cannot get index.

public static IEnumerable<Student> getStudentDetails(IEnumerable<Student> students)
{
    var addressList = getStudentAddress(students);
    var result = students
        .Select((student, index) => (student, index))
        .SelectMany(pair => addressList,
            (pair, address) => (pair, address))
        .Where(p =>
            p.pair.index   1 == p.address.ID &&
            p.pair.student.StudentNumber == p.address.SNumber &&
            p.pair.student.StudentName == p.address.SName &&
            p.pair.student.StudentClass == p.address.SClass)
        .Select(p => (p.pair.student, p.address));

    var studentList = new List<Student>();
        
    foreach (var (student, address) in result)
    {
        addAddress(student, address);
        studentList.Add(student);
    }

    return studentList;
}