How do I create a generic function that uses other functions in the call.

Question

2.00/5 (1 vote)

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I am trying to eliminate a bunch of duplicated code that follows this pattern:

C#

protected OdbcConnection Connection { get; set; }
protected  OdbcCommand Command { get; set;}
protected OdbcDataReader Reader { get; set; }

public string BuildQuery (string parm)
{
    string query = string.Empty;
    // build query
    return query;
}

public void ProcessDataFromReader()
{
    // do something with reader
}

public void GetData()
{
    Command.CommandText = BuildQuery("parms");

    using (Reader = Command.ExecuteReader())
    {
        while (Reader.Read())
        {
             ProcessDataFromReader();
        }
    }
}

I want to create a generic method that handles the methodology above but allow the two functions to be interchangable:
* ProcessDataFromReader()
* BuildQuery("parms")

Thanks

I am trying to build a generic method something like:

C#

public void GetData<T>(Func<object[], string> TQuery, Func<T> TRead)
{
    Command.CommandText = (string)TQuery();

    using (Reader = Command.ExecuteReader())
    {
	while (Reader.Read())
	{
	    TRead();
	}
    }
}

so I can have several queries to execute and be able to read the results of the queries without having to write the same pattern over and over.

Posted 11-May-15 9:33am

tharper1977

Updated 11-May-15 10:28am

v2

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Comments

virusstorm 11-May-15 15:48pm

Are you able to provide an example of how you want to use the generic method? I'm having a hard time following what you want to achieve.

Sascha Lefèvre 11-May-15 16:18pm

Same here. Not quite clear what you want.

Sergey Alexandrovich Kryukov 11-May-15 16:30pm

So, what's the problem with using those functions? Where are the functions you would like to use? Are they generic or not? And so on...
—SA

tharper1977 11-May-15 16:41pm

I would like to have multiple read queries (with parameter lists) and process results for the specific query. I am getting compile errors. I cannot seem to get the parameters to work.

1 solution

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tharper1977 · Accepted Answer · 2015-05-11T10:50:00

I think I have the solution:

C#

{
    public class Class1
    {

        protected OdbcConnection Connection { get; set; }
        protected OdbcCommand Command { get; set; }
        protected OdbcDataReader Reader { get; set; }

        public string BuildQuery1(string parm)
        {
            string query = string.Empty;
            // build query
            return query;
        }

        public string BuildQuery2(string parm1, double parm2)
        {
            string query = string.Empty;
            // build query
            return query;
        }

        public List<int> ProcessDataFromReader1()
        {
            // do something with reader
            return new List<int>();
        }

        public List<double> ProcessDataFromReader2()
        {
            // do something with reader
            return new List<double>();
        }

        public void GetGeneric()
        {
            Func<string> query = delegate { return this.BuildQuery1("parms"); };
            Func<List<int>> read = delegate { return this.ProcessDataFromReader1(); };
            GetData(query, read);
        }

        public void GetGeneric()
        {
            Func<string> query = delegate { return this.BuildQuery2("parms", 10d); };
            Func <List<double>> read = delegate { return this.ProcessDataFromReader2(); };
            GetData(query, read);
        }

        public void GetData<T>(Func<string> TQuery, Func<T> TRead)
        {
            Command.CommandText = TQuery();

            using (Reader = Command.ExecuteReader())
            {
                while (Reader.Read())
                {
                    TRead();
                }
            }
        }
    }
}