X axis as a date

[Erik]

I'm staring with data from SQL server and displaying a chart that has SQL DateTime as the x axis. 

 

string dataQueryString = "Select * from dbo.Data;";

dataCommand = new SqlCommand(dataQueryString, connection);

dataAdapter = new SqlDataAdapter(dataCommand); 

System.Data.DataSet dataDS = new System.Data.DataSet();

dataAdapter.Fill(dataDS, "Data");

 

Chart1.DataSourceSettings.Fields.Add(new FieldMap("date", FieldUsage.XValue));

Chart1.DataSourceSettings.Fields.Add(new FieldMap("rValue", FieldUsage.Value));

 

Chart1.DataSource = dataDS.Tables[0];

 

This works fine and the x axis has the correct date values (e.g. 1/1/2000, 1/2/2000, etc).

 

I then do some processing based on user input, create a DataTable with the new values and then re-display the chart with the new DataTable.

 

At this point I can no longer get the x axis to understand it is a date. If I just copy the date values from the old table to the new I get the following error.

 

Input string was not in a correct format.   at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info,

 Boolean parseDecimal)

at System.Number.ParseDouble(String value, NumberStyles options, NumberFormatInfo numfmt)

at System.Double.Parse(String s, NumberStyles style, NumberFormatInfo info)

at ChartFX.WinForms.DataSourceSettings.a(TypeCode A_0, Object A_1)

at ChartFX.WinForms.DataSourceSettings.a(IDataEx A_0, FieldMapCollection A_1, PropertyDescriptorCollection A_2, b A_3, Boolean A_4)

at ChartFX.WinForms.DataSourceSettings.a()

at ChartFX.WinForms.DataSourceSettings.e()

at ChartFX.WinForms.DataSourceSettings.set_DataSource(Object value)

at ChartFX.WinForms.Chart.set_DataSource(Object value)

 

I can fix this by converting the date into a double value serial date like excel uses (e.g. 12/15/2005 = 38701.00) but that is of course just a numeric value and the x axis no longer displays as a date.

 

Any ideas?

 

[JuanC]

When you say "and then re-display the chart with the new DataTable" are you doing this in a new chart? Are you creating a date-time column in your new DataTable? If the new table's column is not named "date" you may have to clear the fields collection and setup new FieldMaps.

Also I would recommend you try setting the X axis format as follows

chart1.AxisX.LabelsFormat.Format = AxisFormat.DateTime

This might help if you try using double numbers (note that we currently use .ToOADate and but this might change in future versions).

Regards,

 JuanC

[Erik]

I was using the same chart. It works both ways you suggested

Changing either

benchmarkTable.Columns[0].DataType = typeof(DateTime); and use at DateTime object in the row

or

Chart1.AxisX.LabelsFormat.Format = AxisFormat.DateTime; and use the the .ToOADate on the DateTime object.

Thanks for your help!

Erik 

[Frank]

The key here is " create a DataTable ".

You must be creating this DataTable incorrectly. Make sure you give a type to each column, otherwise the default type is string.

[perry3819]

Since ToOADate is used, am I out of luck if my DateTime precision is at the millisecond level?

Thanks,

Perry 

[JuanC]

Internally we use ToOADate and FromOADate when handling dates so if you need to create a chart with precision at the millisecond level, you will have to

1) use doubles in the X axis, using a different conversion method, e.g. you could use .ToFileTimeUTC

2) turn on the Notify property in the X axis and process the chart's GetAxisLabel event, in this event you will return a string e.g. using .FromFileTimeUTC

3) By doing this you will have to manually set your steps, I am guessing that in a chart where milliseconds are important you will typically display less than a date worth of data so losing our "auto steps" calculation will not be a substantial loss in this scenario.

Regards,

JuanC