parse a string with name-value pairs

Question

How can I parse the following string of name-value pair in C#:

string studentDetail = "StudentId=J1123,FirstName=Jack,LastName=Welch,StudentId=k3342,FirstName=Steve,LastName=Smith"

The purpose of parsing this array is to insert values in DB using Linq to SQL:

[HttpPost]
public ActionResult SaveStudent(string studentDetail)
{
    DataContext db = new DataContext();         

    Student student = new Student();
    {
        student.StudentID = //StudentID
        student.FirstName = //FirstName
        student.LastName = //LastName
    };

    db.Student.InsertOnSubmit(student);
    db.SubmitChanges();

    return View();
}

What is the best way of approaching this?

Answer 1

You can split on the comma, then on the equals sign. I put the data into a dictionary for easy access.

string input = "StudentId=J1123,FirstName=Jack,LastName=Welch";

Dictionary<string,string> keyValuePairs = input.Split(',')
  .Select(value => value.Split('='))
  .ToDictionary(pair => pair[0], pair => pair[1]);

string studentId = keyValuePairs["StudentId"];

Note that this isn't validating the input at all to ensure that there are no commas in values, no keys without values, missing keys, etc.

Answer 2

Because the individual student records are not delimited in the input, I would do something like the following:

public class Student
{
    public string Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
} 

and then:

private List<Student> DoSplit(string input)
{
    var theReturn = new List<Student>();
    input = input.Replace(",StudentId=", "|,StudentId=");

    var students = input.Split('|');

    foreach (var student in students)
    {
        var attribs = student.Split(',');
        if (attribs.Count() == 3)
        {
            var s = new Student();
            s.Id = attribs[0].Substring(attribs[0].LastIndexOf('='));
            s.FirstName = attribs[1].Substring(attribs[1].LastIndexOf('='));
            s.LastName = attribs[2].Substring(attribs[2].LastIndexOf('='));

            theReturn.Add(s);
        }
    }

    return theReturn;
}

Again, it's a bit naive because if content contains "=", ",", or "|", there will be failures. You should add some checking in there as well.

Answer 3

Eric Petroelje had a very nice answer at https://stackoverflow.com/a/2049079/59996

Try System.Web.HttpUtility.ParseQueryString, passing in everything after the question mark. You would need to use the System.Web assembly, but it shouldn't require a web context.

(I'm not sure why these two questions aren't linked)

I was able to parse a string of the form a=1&b=2&c=3 using the following code

NameValueCollection nameValueCollection = HttpUtility.ParseQueryString(submission);