Dynamic linq:Creating an extension method that produces JSON result

Question

I'm stuck trying to create a dynamic linq extension method that returns a string in JSON format - I'm using System.Linq.Dynamic and Newtonsoft.Json and I can't get the Linq.Dynamic to parse the "cell=new object[]" part. Perhaps too complex? Any ideas? :

    static void Main(string[] args)
    {
        NorthwindDataContext db = new NorthwindDataContext();
        var query = db.Customers;
        string json = JSonify<Customer>
                        .GetJsonTable(
                            query, 
                            2, 
                            10, 
                            "CustomerID"
                            , 
                            new string[] 
                                { 
                                    "CustomerID", 
                                    "CompanyName", 
                                    "City", 
                                    "Country", 
                                    "Orders.Count"
                                });
        Console.WriteLine(json);
    }

}
public static class JSonify<T>
{
    public static string GetJsonTable(
        this IQueryable<T> query, 
        int pageNumber, 
        int pageSize, 
        string IDColumnName, 
        string[] columnNames)
    {
        string selectItems =
            String.Format(@"
                        new
                        {
                            {{0}} as ID,
                            cell = new object[]{{{1}}}
                        }", 
                          IDColumnName, 
                          String.Join(",", columnNames));

        var items = new
        {
            page = pageNumber,
            total = query.Count(),
            rows =
                query
                    .Select(selectItems)
                    .Skip(pageNumber * pageSize)
                    .Take(pageSize)
        };

        return JavaScriptConvert.SerializeObject(items);
        // Should produce this result:
        // {
        //    "page":2,
        //    "total":91,
        //    "rows":
        //        [
        //        {"ID":"FAMIA","cell":["FAMIA","Familia Arquibaldo","Sao Paulo","Brazil",7]},
        //        {"ID":"FISSA","cell":["FISSA","FISSA Fabrica Inter. Salchichas S.A.","Madrid","Spain",0]},
        //        {"ID":"FOLIG","cell":["FOLIG","Folies gourmandes","Lille","France",5]},
        //        {"ID":"FOLKO","cell":["FOLKO","Folk och fä HB","Bräcke","Sweden",19]},
        //        {"ID":"FRANK","cell":["FRANK","Frankenversand","München","Germany",15]},
        //        {"ID":"FRANR","cell":["FRANR","France restauration","Nantes","France",3]},
        //        {"ID":"FRANS","cell":["FRANS","Franchi S.p.A.","Torino","Italy",6]},
        //        {"ID":"FURIB","cell":["FURIB","Furia Bacalhau e Frutos do Mar","Lisboa","Portugal",8]},
        //        {"ID":"GALED","cell":["GALED","Galería del gastrónomo","Barcelona","Spain",5]},
        //        {"ID":"GODOS","cell":["GODOS","Godos Cocina Típica","Sevilla","Spain",10]}
        //        ]
        // }

    }

}

Answer 1

static void Main(string[] args)
{
    NorthwindDataContext db = new NorthwindDataContext();
    var query = db.Customers;
    string json = query.GetJsonTable<Customer>(2, 10, "CustomerID", new string[] {"CustomerID", "CompanyName", "City", "Country", "Orders.Count" });
 }  

public static class JSonify
{
    public static string GetJsonTable<T>(
     this IQueryable<T> query, int pageNumber, int pageSize, string IDColumnName, string[] columnNames)
    {
     string select = string.Format("new ({0} as ID, new ({1}) as cell)", IDColumnName, string.Join(",",     columnNames));
     var items = new
     {
      page = pageNumber,
      total = query.Count(),
      rows = query.Select(select).Skip((pageNumber - 1) * pageSize).Take(pageSize)
     };
     return JavaScriptConvert.SerializeObject(items);
    }
}

Answer 2

Thanks for the quick response. However, note the required output does not have property names in the "cell" array ( that's why I was using object[]):

"cell":["FAMIA","Familia Arquibaldo",... vs. "cell":{"CustomerID":"FAMIA","CompanyName","Familia Arquibaldo",...

The result is meant to be used with a JQuery grid called "flexify" which requires the output in this format.

Answer 3

This is really ugly and there may be some issues with the string replacement, but it produces the expected results:

public static class JSonify
{
    public static string GetJsonTable<T>(
     this IQueryable<T> query, int pageNumber, int pageSize, string IDColumnName, string[] columnNames)
    {
     string select = string.Format("new ({0} as ID, \"CELLSTART\" as CELLSTART, {1}, \"CELLEND\" as CELLEND)", IDColumnName, string.Join(",", columnNames));
     var items = new
     {
      page = pageNumber,
      total = query.Count(),
      rows = query.Select(select).Skip((pageNumber - 1) * pageSize).Take(pageSize)
     };
     string json = JavaScriptConvert.SerializeObject(items);
     json = json.Replace("\"CELLSTART\":\"CELLSTART\",", "\"cell\":[");
     json = json.Replace(",\"CELLEND\":\"CELLEND\"", "]");
     foreach (string column in columnNames)
     {
      json = json.Replace("\"" + column + "\":", "");
     }
     return json;
    }
}