Regex to match mostly alphanumeric paths

Question

I tried creating a regular expression to verify path names for a filesystem API I write using GridFS.

My current RegEx ^[A-Za-z0-9\\-\\[\\]()$#_./]*$ can fulfill this criteria:

• Allow az , AZ , 0-9 , -[]()$#_./

However it doesn't meet these additional criteria:

• First Character has to be /
• There mustn't be any occurrence of multiple / in a row.

Questions:

• Can anybody help me fix my RegEx?
• Are there any possible issues for using my criteria for path names? (Did I miss anything important?)

Answer 1

Not sure about the path criteria, but regarding the RegExp, pretty simple:

^\/(?!\/)([A-Za-z0-9\-\[\]()$#_.]|(\/(?!\/)))*$

\\/(?!\\/) means a slash / not followed by a slash (?!\\/) . I used it twice, once as the first character, and again as one of the possible matches after the first character.

Answer 2

Here's how you could address your requirements. To enforce the first character is / , simply add that after the ^ .

^\\/[A-Za-z0-9\\-\\[\\]()$#_./]*$

To not allow consecutive slashes, you should remove it from your character set, and think of the set as a portion of the path. Portions would be separated by a slash. So the final regex would be:

^\\/([A-Za-z0-9\\-\\[\\]()$#_.]\\/?)*$