C # get parameter GetParameter

Yesterday encountered a problem, getparameter, when the first time to enter the page to read the default value, should have read "all" this character.

Then in the actual read process is not so, the actual reading is the object value of the class

Ability to read "All" when re-running

So I asked the great God to help me solve the problem and ask why the problem occurred.

Details are as follows:

There are two drop-down boxes, drop-down boxes 1, and drop-down boxes 2

The data in the dropdown box 2 is changed according to the data of the dropdown box 1.

For the first time, the default value for drop-down box 1 is "All", and the drop-down box 2 should be "All" by default, but it is not.

After telling the details, I was told that this is the reason why the default value for drop-down box 2 does not have data

Start modifying, get data, drop-down box 1 and drop-down box 2 data at the same time get

When the data of the dropdown box 1 = "All", the drop-down box 1 of the Id= "", while the drop-down box 2 of the id= "";

The data in the dropdown box 1! = "All", drop-down box 1 of the id= "corresponding value", drop-down box 2 Id= "based on the 1 ID get"

So get the data, run, perfect!

How can a rookie like me get away with the help of a great God?

C # get parameter GetParameter