Bound datagridview not updating
Microsoft provide data binding and go to the extreme lengths to provide masses of support for this rapid application development feature, but then screw us all with the error handling and event order. The answer is to retrieve the record in a Row and then test it for null as you can see below: : : Item Table = Item Adapter. Reply Hi there Smalltime, It sounds like you’re using data binding.In actual fact the only real solution is to trap this error and clear it. You might want to try checking the data on the textbox by interrogating the bindingsource object instead of the actual form field.However, the null thing is making this a little more difficult then I expected.Also F1 help is so cryptic that I end up swallowing MAX painkillers and the left side of my chair is now showing distinct scratch marks inflicted out of F1 frustration.So what do we do with folders that don’t have parents? Only because of this bug in the Dataset Designer, we are forced to throw an exception each time a null is encountered. One very frustrated developer and countless confusing error messages. I ended up (and it remains to be seen if it was a horrible mistake) deciding to avoid all of it, and I store data as objects, so they are nullable, and can be… So far so good, although I must admit making sure that null and type is handled gracefully all the time does take work.The Dataset Designer Null values were incorporated using the System. NET 2.0 framework for all datatypes, but someone appeared to have forgotten to tell the Dataset designer team, because when you try to change the Null Value property to anything other than (Throw Exception) you get a Properties Window warning and the property returns to (Throw Exception): Property value is not valid The value entered isnot valid for the current data type Null Value (Throw exception) If your Data Type is a System. 🙂 Reply My suggestion is do NOT use datasets, they appear really cool, neat and easy to use at first but then become horribly cumbersome as your application matures.Although the underlying database allows nulls in this column, Visual Studio’s much promoted dataset designer (still in 2008) doesn’t allow the developer to allow null values in any other data type than a System. For example on a product I am currently working on which uses Visual Studio 2008, .
This only works you open the Dataset Designer again. Example Comments Please If you’re a software developer you have probably found this page by ferociously Googling for the answer to your problem. I’d be interested to find out if you’ve got a better solution for handling nulls or if you can improve on my workaround above. DBNull value rather than a hacked “-1”, so if you know how this is done please drop me a comment. I did put the msprop:null Value=“-1” in my XSD file but later regenerated the method and the change was gone.
But then it makes the project a pain to debug properly because these dataset errors keep being thrown when you don’t want to know about them. Although I thought that even if invisible you should still be able to check the value of an .visible=false textbox.
Once you’re over the learning curve it is worth it but in the meantime I can share in your frustration.
Reply Hi, I went for your workaround mike, but then I realized that there was a way to not have a workaround but a more reliable solution maybe as we won’t fear to loose our changes: Instead of changing the code in the xsd and adding msprop:null Value=“-1” nillable=“true” , we can just set the value -1 to the Null Value parameter via the designer. Regards, Julien Reply Hi, i did not have that problem although i’m using data binding on winforms including binding sources and dgvs.
The difference is that we don’t have this part added in the xsd: nillable=“true” . I ‘ve set the Allow DBNull = true in the XSD Designer and set the Null Value to -1.