Delimiter to use within a query string value

string query-string delimiter
Matthew Cole picture Matthew Cole · Mar 13, 2009 · Viewed 37.9k times · Source

I need to accept a list of file names in a query string. ie: 

http://someSite/someApp/myUtil.ashx?files=file1.txt|file2.bmp|file3.doc

Do you have any recommendations on what delimiter to use?

Answer

Cory Kendall picture Cory Kendall · Jan 9, 2013

Having query parameters multiple times is legal, and the only way to guarantee no parsing problems in all cases:

http://someSite/someApp/myUtil.ashx?file=file1.txt&file=file2.bmp&file=file3.doc

The semicolon ; must be URI encoded if part of a filename (turned to %3B), yet not if it is separating query parameters which is its reserved use.

See section 2.2 of this rfc:

2.2. Reserved Characters

URIs include components and subcomponents that are delimited by characters in the "reserved" set. These characters are called "reserved" because they may (or may not) be defined as delimiters by the generic syntax, by each scheme-specific syntax, or by the implementation-specific syntax of a URI's dereferencing algorithm. If data for a URI component would conflict with a reserved character's purpose as a delimiter, then the conflicting data must be percent-encoded before the URI is formed.

 reserved    = gen-delims / sub-delims

 gen-delims  = ":" / "/" / "?" / "#" / "[" / "]" / "@"

 sub-delims  = "!" / "$" / "&" / "'" / "(" / ")"
             / "*" / "+" / "," / ";" / "="

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