问题
I'm trying to create an extended gridview class that will enable me to always have a footerrow that can be used to add data. That's the end goal.
I've tried classes that were found elsewhere on stackoverflow, but the code I found is apparently buggy (it either works when the footerrow is the only row, or it works when the footerrow is not the only row, but never both. Possibly related to the fact that I have dropdownlists in my rows). This problem was explained here: Bizarre issue with customized gridview control
The class itself is also problematic, in that the formatting is kind of messed up when the footerrow is the only row. It just doesn't look right... the color formatting is gone.
So now I'm thinking what I really want to do, is rewrite the data sources so they're based on UNION queries, so that there's always one blank row with -1 in the key column (my tables always have single incremental primary keys, so no legit row will ever have -1 in the key column), and then have a class that automatically hides any row where the value in the "DataKeyNames" field is -1.
Problem: I have no idea how to do this. :) I know how to do it in the aspx.cs code (RowDataBound event -- if(condition) {e.Row.Visible = false;}), and I know how to do it via CSS, but I don't know how to do it automatically in an extended class. I'm afraid I'm a little lost when it comes to writing extended classes.
To sum up, what I'd like to do is put an extended gridview class in my aspx code, set the usual gridview things, and have the only additional thing in my code be an added "UNION SELECT" in my datasource, and have it just automatically hide the row that the UNION SELECT provided, so that there's always at least one row in the gridview (thereby taking care of the entire footerrow not showing up problem), without me having to code anything extra in a RowDataBound event every time, because I have these gridview controls EVERYWHERE in my code.
Many thanks for any help you can provide! :)
来源：https://stackoverflow.com/questions/49524212/c-sharp-gridview-want-to-create-an-extended-gridview-class-that-automatically-h