Question

I have the following code.
All 20 objects seem to get created ok.
The first foreach then works fine and iterates through all 20.
The second example using linq works well aswell.

Is it then possible to target just one of the objects, using a property such as ReportKey, and run the method RunThisReport just for that object? Or, because I’ve used the type IEnumerable<> have I gone down a dead-end?

static void Main(string[] args) {

    var models = SelectReports("SELECT * FROM 20RecordTable");

     //1.running the method for each
    foreach(myReport x in models) {
        Console.WriteLine("Doubled key:{0}",  x.myReportKeyDoubled().ToString());
    }

    //2.linq sample
    var result = from sample in models
                    select sample.ReportName;
    foreach(string x in result) {
        Console.WriteLine(Convert.ToString(x));
    }

    //3. target a single report say reportKey 512 and run the method RunThisReport?

    Console.WriteLine("Press [enter] to exit");
    Console.Read();
}

static IEnumerable<myReport> SelectReports(string myCommandText) {

    var connectionString = ConfigurationManager.ConnectionStrings["xxx"].ConnectionString;
    using(var conn = new SqlConnection(connectionString))
    using(var cmd = conn.CreateCommand()) {
        conn.Open();
        cmd.CommandText = myCommandText;
        using(var reader = cmd.ExecuteReader()) {

            while(reader.Read()) {
                yield return new myReport {

                    ReportKey = reader.GetInt32(reader.GetOrdinal("ReportKey")),
                    ReportName  = reader.GetString(reader.GetOrdinal("ReportName")),
                    ReportDescription  = reader.GetString(reader.GetOrdinal("ReportDescription")),
                    ReportTechDescription = reader.GetString(reader.GetOrdinal("ReportTechDescription "))

                };
            }
        }
    }
}

public class myReport {

    public int ReportKey { get; set; }
    public string ReportName { get; set; }
    public string ReportDescription { get; set; }
    public string ReportTechDescription { get; set; }

    public int myReportKeyDoubled() {
        return ReportKey*2;
    }
    public string RunThisReport(){
        return this.ReportName + " needs to be run via" + this.ReportTechDescription;
    }         
}

Answer 1

 var report = models.SingleOrDefault(m => m.ReportKey == 512);

 if (report != null)
     report.RunThisReport();

Or with comprehension syntax (ugly, yes?):

var report = (from m in models
              where m.ReportKey == 512
              select m).SingleOrDefault();

BTW with Dapper your code will look like:

static IEnumerable<myReport> SelectReports(string myCommandText) 
{    
    var connectionString = ConfigurationManager.ConnectionStrings["xxx"].ConnectionString;
    using(var conn = new SqlConnection(connectionString))
    {
        conn.Open();
        return conn.Query<myReport>(myCommandText);    
    }
}

Dapper is available via NuGet. And it’s my choice when working with ADO.NET