Question

Background:

1. Developing a trading system which subscribe to many events which are sent by API of Interactive Brokers. One interesting event is about my trading account value which fluctuates during trading hour so I would prefer to see the information with accountvalueupdate event immediately. I develop this one based on ActiveX api and c# in Visual Studio 2010.

2. the presentation I wanna check this information is to use a gauge developed by(http://www.devexpress.com/Products/NET/Controls/WinForms/Gauges/). This gauge looks fancy but the principle should be similar to the normal gauge we use in Visual Studio. It seems like I could only update the value of the gauge by databinding since I tried to assign updated account value to this.myGauge.value and failed.

3. I build up MySql connection between MySql and VS2010. I create only one table in MySQL which is called account. For the sake of simplicity, i only have two column(accountID and accountValue) and one row|(which means when event comes with new accountValue, I just overwrite the value of accountValue last session then the number of row is always one. really simple idea…..).In that Gauge proporties I found databinng option and I setted up by using advanced option to navigate throw available table and bind it to the only useful column accountValue.

Issue:

1. I set up the default value of the accountValue as 500 as default for test. I build my software. The gauge shows 500 correctly.
2. Of course, my real account value is not 500, so Now I click one button to connect to API and start listening the event. After few seconds, event arrives since I opened on Console for managing the mysql table and use select * from account to continuously watch the update. I noticed the value of accountValue column(TABLE WORKS RIGHT AND WE ONLY HAVE ONE ROW, OEVERWRITTING MODE) becomes the right one, for example, 35000.

HOWEVER, THE GAUGE DOES NOT CHANGE AT ALL…!! Now If i closed my software and build again, the gauge shows the right value 35000. Now I shut down the api and no coming event and only use commandline of mysql to change the value of accountValue again to 500. NO UPDATING in gauge as well.

It looks like the gauge only read the value of table during the build session or when it starts and never listen to the update of binding databases.

By the way, I tried to set up the biding data mode to either “onValidation” or “onPropertieschanged” but it does not solve although the “onPropertieschanged” looks the right one….

Answer 1

I tried to assign updated account value to this.myGauge.value…

Unfortunately, the information you provided doesn’t allow to clearly diagnose this problem. There is no the Value property neither in WinForms GaugeControl nor in CircularGauge (as soon as in Linear/Digital/StateIndicator gauge), but only in ASPxGaugeControl (ASPxGaugeControl.Value). So, please provide a full sample code that doesnot work on your side.

All these properties can be changed manually in code or data-bound to data sources using the standard .NET data-binding mechanism:

• The ArcScaleComponent.DataBindings property allows you to data-bind
  to the current value of a circular gauge’s scale (ArcScale.Value).
• The LinearScaleComponent.DataBindings property allows you to
  data-bind to the current value of a linear gauge’s scale
  (LinearScale.Value).
• The DigitalGauge.DataBindings property allows you to data-bind to the
  text displayed by a digital gauge.
• The StateIndicatorComponent.DataBindings property allows you to
  data-bind to a state of a state indicator gauge.

Please, review the following articles for more details: Data Binding.
The databinding feature is demonstrated in the Gauge’s Main Demo project (the DataBinding module):

this.arcScaleComponent2.DataBindings.Add(
    new System.Windows.Forms.Binding("Value", this.productsBindingSource,
    "UnitsOnOrder", true, System.Windows.Forms.DataSourceUpdateMode.Never));

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