C＃如何将字符串添加到列表，以便可以从DataSource访问它们

Question

i am doing this:

    List<string> list = new List<string>();
    while (myReader.Read())
    {
        reporttime = (string)myReader["reporttime"];
        datapath = (string)myReader["datapath"];

        list.Add(reporttime,datapath);
    }


    chart1.DataSource = list;

i am not exactly sure how i should be donig the list.Add in order to be able to do the following:

chart1.Series["Series1"].XValueMember = "reporttime";
  chart1.Series["Series1"].YValueMembers = "datapath";

question: how should i be adding the items to the list?

Answer 1

It might work simply by doing

chart1.DataSource = myReader;
chart1.Series["Series1"].XValueMember = "reporttime";
chart1.Series["Series1"].YValueMembers = "datapath";
chart1.DataBind();

, as the documentation says the chart can bind from a data reader:

http://msdn.microsoft.com/en-us/library/system.web.ui.datavisualization.charting.chart.datasource.aspx

The following is a list of objects that you can use as the data source:

DataView

Data readers (SQL, OleDB)

DataSet

DataTable

[...]

Answer 2

There are other good answers, but since your comment asked how to use a DataTable instead I'll post this anyway. Besides, I don't see how those answers will let you specify the value members, because the code examples I've seen require a named item, and a list of strongs isn't going to do it. (See @Dan's post).

Instead of using a DataReader and using while(reader.Read())

use a DataAdapter to fill the datatable. (Assuming the DB is SQL Server, you'd use a SQLDataAdapter , but there are different DataAdapters.

string connectionstring = "Some connection sting";
string sql = "Select reporttime, datapath from sometable";
System.Data.DataTable t = new System.Data.DataTable();
System.Data.SqlClient.SqlDataAdapter ad = new System.Data.SqlClient.SqlDataAdapter(sql, connectionstring);
ad.Fill(t);

chart1.DataSource = t;

chart1.Series["Series1"].XValueMember = "reporttime";  
chart1.Series["Series1"].YValueMembers = "datapath"; 

Answer 3

List.Add is for one item only. To add multiple items, you would want AddRange:

list.AddRange(new[] { reporttime,datapath,finalconc,DBinstrument } );

However, if you're binding to this, it sounds like you want a list of objects, not strings...so something more like

List<object> list = new List<object>();
while (myReader.Read())
{
    reporttime = (string)myReader["reporttime"];
    datapath = (string)myReader["datapath"];

    list.Add(new {
       reporttime = (string)myReader["reporttime"],
       datapath = (string)myReader["datapath"]
       finalconc = "something",
       DBinstrument = "somethingelse?"
    });
}


chart1.DataSource = list;

Note, I would suggest in practice creating a business object for this instead of using an anonymous one.