How do I display data on a chart control based on a selected item that I have selected from a dropdownlist

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I want to display data from an SQL database to a chart control on my view layer. I want to display data based on an item that I selected and get the corresponding data to display on a chart control. Below is the code that I used but nothing is being displayed and it does not give me any errors.

This is my method in the business logic layer that I use to return the data.

C#

public List<durbanvotes> Get_DBNVotes(string year,string region)
        {
            csDAL objdal = new csDAL();
            List<durbanvotes> objvotes = new List<durbanvotes>();
            List<csparameterlisttype> parlist = new List<csparameterlisttype>();
            IDataReader dr = null;
            parlist.Add(new csParameterListType("@standingyear", SqlDbType.VarChar, year));
            parlist.Add(new csParameterListType("@region", SqlDbType.VarChar, region));
            dr = objdal.executespreturndr("Get_region_latest_Votes", parlist);
            while (dr.Read())
            {
                DurbanVotes objp = new DurbanVotes();
                populate_reader(dr, objp);
                objvotes.Add(objp);
            }

            return objvotes;

        }


  private void populate_reader(System.Data.IDataReader dr, DurbanVotes objp)
        {
            objp.Candidate_Name = dr.GetString(0);
            objp.Total_Votes_perc =Convert .ToString ( dr.GetInt32(1)+" %");
        }       
    }</csparameterlisttype></csparameterlisttype></durbanvotes></durbanvotes></durbanvotes>

This is the code behind my form that I am using to return the data.

C#

protected void btnsearch_Click(object sender, EventArgs e)
      {
          string year = ddyear.SelectedItem.Text .ToString ();
          string region = ddregion.SelectedValue.ToString();
          {
          Business_Logic.DurbanVotes objc = new DurbanVotes();
          Chart1.Titles.Add("Latest Results");
          Chart1 .DataSource = objc.Get_DBNVotes(year, region);
          Chart1.Series[0].XValueMember = "Candidates";
          Chart1.Series[0].YValueMembers = "Votes";
          Chart1.DataBind();
          }
      }

Posted 30-Sep-11 7:44am

P.C Shabangu

Updated 30-Sep-11 7:54am

André Kraak

v2

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Tejas Vaishnav 1-Oct-11 2:22am

Can you show your sp or query through which you select data from database..

and also display sample data which you want to show...

3 solutions

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Ganesan Senthilvel · Answer 1 · 2011-10-02T23:13:00

I'm not sure about no error. Why don't you try with try..catch block.

C#

public List<durbanvotes> Get_DBNVotes(string year,string region)
        {
        try {
            csDAL objdal = new csDAL();
            List<durbanvotes> objvotes = new List<durbanvotes>();
            List<csparameterlisttype> parlist = new List<csparameterlisttype>();
            IDataReader dr = null;
            parlist.Add(new csParameterListType("@standingyear", SqlDbType.VarChar, year));
            parlist.Add(new csParameterListType("@region", SqlDbType.VarChar, region));
            dr = objdal.executespreturndr("Get_region_latest_Votes", parlist);
            while (dr.Read())
            {
                DurbanVotes objp = new DurbanVotes();
                populate_reader(dr, objp);
                objvotes.Add(objp);
            }

            return objvotes;
        }
        catch (Exception ex){
        }
        }

BobJanova · Answer 2 · 2011-10-03T05:49:00

Minor point: that method should be static, as it doesn't use any instance information. Then you could remove the creation of a pointless object in the binding process.

At first glance it looks ok. Make sure that there actually are no errors in Get_DBNVotes, and that it is returning a non-empty list (putting a stop on the 'return objvotes' line should be a good way to achieve that if your IDE supports debugging).

Make sure that the column names you're asking for in the chart are the same as the property names on the object. It looks like they're not: try

Chart1.Series[0].XValueMember = "Candidate_Name";
Chart1.Series[0].YValueMembers = "Total_Votes_perc";

I'd expect that to throw an exception if that were the case, though.

Ganesan Senthilvel · Answer 3 · 2011-10-02T23:13:00

I'm not sure about no error. Why don't you try with try..catch block.

C#

public List<durbanvotes> Get_DBNVotes(string year,string region)
        {
        try {
            csDAL objdal = new csDAL();
            List<durbanvotes> objvotes = new List<durbanvotes>();
            List<csparameterlisttype> parlist = new List<csparameterlisttype>();
            IDataReader dr = null;
            parlist.Add(new csParameterListType("@standingyear", SqlDbType.VarChar, year));
            parlist.Add(new csParameterListType("@region", SqlDbType.VarChar, region));
            dr = objdal.executespreturndr("Get_region_latest_Votes", parlist);
            while (dr.Read())
            {
                DurbanVotes objp = new DurbanVotes();
                populate_reader(dr, objp);
                objvotes.Add(objp);
            }

            return objvotes;
        }
        catch (Exception ex){
        }
        }

How do I display data on a chart control based on a selected item that I have selected from a dropdownlist

3 solutions

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