问题
Quick question, I have tried figuring this out myself, but the use of Session Variables can be confusing when trying to figure out why or how a page is reloading and doing/not doing what it is supposed to do.
Does a page reload (with JavaScript, f5, ctrl+f5, browser reload button, etc) ever, under any (non-scripted) circumstance cause a form repost?
(This pertains to using IfPost branches within C# code like the example code below):
if(IsPost)
{
//stuff that only executes if the previous request was a post.
}
I just kind of need to know what to expect here so I can properly diagnose my session state problems.
Thanks for any help!
(Also, sorry if I am oversimplifying this question. I realize that it \'may\' be more complicated than a simple answer can provide).
******UPDATE********** Also, I looked for copies of this question here, on StackOverflow, but I didn\'t see anything, so if this is a duplicate question, I apologize.
Both of the answers here are good answers. I accepted the answer that also offered a solution to my question, and while PRG is not the \'only\' way to do it, it seems like it may be the best. It also seems a growing way to handle client-side user-friendliness, and imho, seems like it would be a great habit to get into.
Thanks for showing me that!
回答1:
Yes. If the page was loaded using POST data this will occur. To prevent this you need to implement the POST/REDIRECT/GET pattern.
Post/Redirect/Get (PRG) is a web development design pattern that prevents some duplicate form submissions, creating a more intuitive interface for user agents (users). PRG supports bookmarks and the refresh button in a predictable way that does not create duplicate form submissions.
回答2:
Yes. If someone refreshes the browser manually, it will ask them if they want to send the form data again. This will cause that code to get executed.
回答3:
A way to handle this is using tokens.
- Send a random string along with the post data
- Store this random string somewhere
- When you check the post data make sure that the stored string is the same as the string in the post request.
- If true, handle the request.
- Generate a new token
If someone were to refresh and resend the post data, your token in the post request will be different from the one you stored separately since you generated a new token at step 5
来源：https://stackoverflow.com/questions/13883917/does-page-reload-ever-cause-post