/// <summary>
/// Returns the entries using the predicate.
/// The total count of records matching the predicate is returned in
/// Http header "EntryCount".
/// </summary>
/// <param name="predicate"></param>
/// <param name="skip"></param>
/// <param name="take"></param>
/// <returns></returns>
[WebGet]
public IEnumerable<Entries> GetEntries(string predicate, string orderKeys, int skip, int take)
{
    // TODO: Security check.
    if (orderKeys == null || orderKeys.Length == 0)
        throw new DataServiceException("orderKeys required.");
    // Get the records using skip and take.
    IEnumerable<Entries> q = null;
    int count = 0;
    if (predicate == null || predicate.Length == 0)
    {
        q = this.CurrentDataSource.Entries.OrderBy(orderKeys).Skip(skip).Take(take);
        count = this.CurrentDataSource.Entries.Count();
    }
    else
    {
        q = this.CurrentDataSource.Entries.Where(predicate).OrderBy(orderKeys).Skip(skip).Take(take);
        count = this.CurrentDataSource.Entries.Where(predicate).Count();
    }

    // Get the count all records matching predicate and add to HTTP header.
    HttpContext.Current.Response.AppendHeader("EntryCount", count.ToString());
    return q;
}

/// <summary>
/// Get entries using a string predicate and read the total count in the reply header.
/// </summary>
/// <param name="predicate"></param>
/// <param name="skip"></param>
/// <param name="take"></param>
/// <returns></returns>
public IEnumerable<Entries> GetEntries(string predicate, string orderBy, int skip, int take, out int count)
{ 
    // Why this work around? We have to pass an eSql string for the predicate instead of composing over IQueryable,
    // because at the server side we need to "know" the full predicate in order to get the count.
    // This also allows us to use the same query for the count and the select.
    if (predicate == null) predicate = "";      // Empty predicate on server side equals all rows.
    if (orderBy == null) throw new ArgumentNullException("orderKeys"); // order clause required.

    predicate = predicate.Replace("'", "''");   // Must add another single quote as these will be inside a single quote pair.
    string request = string.Format("GetEntries?predicate='{0}'&orderKeys='{1}'&skip={2}&take={3}", predicate, orderBy, skip, take);
    request = Uri.EscapeUriString(request);     // Escape spaces and other.
    var q = this.Execute<Entries>(request.ToRelativeUri()); // Have to Execute (not CreateQuery) so we can inspect the header here.

    // Get full record count in header.
    var qReply = (QueryOperationResponse)q;     // Downcast to get the Headers in the reply.
    Debug.WriteLine("Request URI: " + qReply.Query.RequestUri);
    string cs = qReply.Headers["EntryCount"];
    count = int.Parse(cs);
    return q;
}

public void ConvertCsvToObjects()
{
    string csv = File.ReadAllText(@"c:\temp\mycsv.txt");
    /* mycsv.txt - Note the doube quotes around strings are required by json.
    ID, Name, Price
    1, "ABC", 1200.00
    2, "Zip Co.", 1400
    3, "Contoso", 5000
     */

    // Step 1: Reshape csv to a json array format.
    string json = csv.CsvToJson();
    Console.WriteLine(json);
    /* JSON text
    [ 
    {ID: 1, Name: "ABC", Price: 1200.00},
    {ID: 2, Name: "Zip Co.", Price: 1400},
    {ID: 3, Name: "Contoso", Price: 5000}
    ]
    */

    // Step 2: Convert json to objects.
    List<Customer> customers = json.FromJson<List<Customer>>();
    foreach(var cust in customers)
        Console.WriteLine("{0}\t{1}\t{2:c}", cust.ID, cust.Name, cust.Price);
    /* Output.
    1    ABC    $1,200.00
    2    Zip Co.    $1,400.00
    3    Contoso    $5,000.00
     */
}

public class Customer
{
    public int ID {get;set;}
    public string Name { get; set; }
    public decimal Price { get; set; }
}

/// <summary>
/// Converts a CSV string to a Json array format.
/// </summary>
/// <remarks>First line in CSV must be a header with field name columns.</remarks>
/// <param name="value"></param>
/// <returns></returns>
public static string CsvToJson(this string value)
{
    // Get lines.
    if (value == null) return null;
    string[] lines = value.Split(new string[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
    if (lines.Length < 2) throw new InvalidDataException("Must have header line.");

    // Get headers.
    string[] headers = lines.First().SplitQuotedLine(new char[] { ',' }, false);

    // Build JSON array.
    StringBuilder sb = new StringBuilder();
    sb.AppendLine("[");
    for (int i = 1; i < lines.Length; i++)
    {
        string[] fields = lines[i].SplitQuotedLine(new char[] { ',', ' ' }, true, '"', false);
        if (fields.Length != headers.Length) throw new InvalidDataException("Field count must match header count.");
        var jsonElements = headers.Zip(fields, (header, field) => string.Format("{0}: {1}", header, field)).ToArray();
        string jsonObject = "{" + string.Format("{0}", string.Join(",", jsonElements)) + "}";
        if (i < lines.Length - 1)
            jsonObject += ",";
        sb.AppendLine(jsonObject);
    }
    sb.AppendLine("]");
    return sb.ToString();
}

public static T FromJson<T>(this string json)
{
    JavaScriptSerializer ser = new JavaScriptSerializer();
    return ser.Deserialize<T>(json);
}