Converting Data in a C# List from one type to another.

Question

I am trying to learn Linq a little better so I apologies in advance if this is a silly question.

Given the following classes:

class FormData 
{
   public string CustomerId {get; set;}
   public string FieldId {get; set;} 
   public string FieldValue {get; set;}
}

class CustomerDetails 
{
   public string CustomerId {get; set;}
   public FormField[] Fields {get; set;} 
}

class FormField
{
   public string FieldId {get; set;}
   public string FieldValue {get; set;} 
}

I'm trying to convert this data

// example incoming data set 
List<FormData> formData = new List<FormData> {
   new FormData { CustomerId = 1, FieldId = "FirstName", FieldValue = "Peter" },   
   new FormData { CustomerId = 1, FieldId = "LastName", FieldValue = "Smith" },   
   new FormData { CustomerId = 1, FieldId = "PetsName", FieldValue = "Spot" },  
   new FormData { CustomerId = 2, FieldId = "FirstName", FieldValue = "Dougie" },   
   new FormData { CustomerId = 2, FieldId = "LastName", FieldValue = "Fresh" },   
   new FormData { CustomerId = 2, FieldId = "PetsName", FieldValue = "Skittles" }, 
   new FormData { CustomerId = 3, FieldId = "FirstName", FieldValue = "Sam" },   
   new FormData { CustomerId = 3, FieldId = "LastName", FieldValue = "Reynolds" },   
   new FormData { CustomerId = 3, FieldId = "PetsName", FieldValue = "Taco" }              
};

to this

// desired out going data set 
List<CustomerDetails> customerDetails = new List<CustomerDetails> {
   new CustomerDetails {
    CustomerId : 1, 
    Fields : [
           new FormField {FieldId = "FirstName", FieldValue = "Peter"}, 
           new FormField {FieldId = "LastName", FieldValue = "Smith"},
           new FormField {FieldId = "PetsName", FieldValue = "Spot"}
        ]
    },
   new CustomerDetails {
    CustomerId : 2, 
    Fields : [
           new FormField {FieldId = "FirstName", FieldValue = "Dougie"}, 
           new FormField {FieldId = "LastName", FieldValue = "Fresh"},
           new FormField {FieldId = "PetsName", FieldValue = "Skittles"}
        ]
    },
   new CustomerDetails {
    CustomerId : 3, 
    Fields : [
           new FormField {FieldId = "FirstName", FieldValue = "Sam"}, 
           new FormField {FieldId = "LastName", FieldValue = "Reynolds"},
           new FormField {FieldId = "PetsName", FieldValue = "Taco"}
        ]
    }
};

Here's how I'm currently doing it... there's gotta be a better way right?

var customerIds = formData.Distinct().Select(x => x.CustomerId).ToList();

var results = new List<CustomerDetails>(); 

foreach (var id in customerIds)
{
    var customerDetails = new CustomerDetails();
    customerDetails.CustomerId = id;

    var fields = new List<GuestItemDataFieldResult>(); 

    foreach (var f in formData.Where(x => x.CustomerId == id))
    {
    var field = new FormField();
        field.FirstName = f.FirstName; 
        field.LastName = f.LastName; 
        field.PetsName = f.PetsName;

        fields.Add(field); 
    }

    customerDetails.Fields = fields.ToArray(); 

    results.Add(customerDetails); 
}

What would you consider to be better? Less code? Faster processing? — LVBen
– LVBen, Commented Jul 9, 2014 at 2:00
@mclaassen I believe GroupBy is what I'm looking for but I can't wrap my head around the syntax (pretty new to LINQ still). — McCheeseIt
– McCheeseIt, Commented Jul 9, 2014 at 2:04
@paqogomez can't install any third party libraries per client specs... weak! — McCheeseIt
– McCheeseIt, Commented Jul 9, 2014 at 2:12
Talk to someone, modify the specs. JSON.Net is the way to handle json objects, which is what you're creating. — crthompson
– crthompson, Commented Jul 9, 2014 at 2:14
Not being able to use 3rd party libs is a silly requirement. — mclaassen
– mclaassen, Commented Jul 9, 2014 at 2:16

Darek · Accepted Answer · 2014-07-09 01:59:51Z

6

Here you go:

var newData =
    formData.GroupBy(g1 => g1.CustomerId)
        .Select(
            s1 =>
                new CustomerDetails
                {
                    CustomerId = s1.Key.ToString(),
                    Fields =
                        s1.Select(s2 => new FormField {
                                FieldId = s2.FieldId, 
                                FieldValue = s2.FieldValue})
                            .ToArray()
                });

answered Jul 9, 2014 at 1:59

Darek

4,80534 silver badges48 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Kyle Gobel Over a year ago

that s1 => on it's own line is killing me

Collectives™ on Stack Overflow

Converting Data in a C# List from one type to another.

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related