Scala/Gatling中Regex、/与"的使用及bid_kid令牌提取

Hey there! Let's break down how to extract that bid_kid token from the HTML <head> using Scala/Gatling, plus clear up how regex, /, and " work in this context.

First, let's cover common scenarios for where bid_kid might live in your <head> section, and how to capture it with Gatling.

Case 1: bid_kid in a Meta Tag #

If your HTML includes a meta tag like this:

You can use Gatling's regex extractor in your HTTP request to capture the token and save it to a session variable:

.exec(http("Fetch Login Page")
  .get("/your-login-url")
  .check(regex("""<meta name="bid_kid" content="([^"]+)"""").saveAs("bidKid")))

If the HTML uses HTML entities (") instead of literal quotes (like <meta name=&quot;bid_kid&quot; content=&quot;your-token-here&quot; />), adjust the regex to match the entity string:

.exec(http("Fetch Login Page")
  .get("/your-login-url")
  .check(regex("""<meta name=&quot;bid_kid&quot; content=&quot;([^&]+)&quot;""").saveAs("bidKid")))

Case 2: bid_kid in a Script Variable #

If the token is defined inside a <script> tag (e.g., <script>var bid_kid = "your-token-here";</script>), tweak the regex to target the variable assignment:

.exec(http("Fetch Login Page")
  .get("/your-login-url")
  .check(regex("""var bid_kid = "([^"]+)";""").saveAs("bidKid")))

1. Regex Basics in Gatling #

Gatling leverages Java's regex engine. In Scala, we use triple quotes (""") for regex patterns to avoid having to escape backslashes (which would be required in standard double-quoted strings). For example:

• """(\d+)""" (triple quotes) = "\\d+" (standard string)

The regex parts we used:

• ([^"]+): Captures one or more characters that are not a double quote—perfect for grabbing the token without including the closing quote.
• ([^&]+): Used when dealing with " to capture until the next & (since the entity ends with ;, this ensures we don't include the closing ").

2. The / Character in Regex #

In regex, / is just a literal character—no special meaning here. You don't need to escape it unless you're using it as a delimiter (which isn't the case in Scala/Gatling). If your bid_kid includes slashes (e.g., abc/123/xyz), the regex ([^"]+) will capture it correctly without any extra work.

3. " in HTML #

" is the HTML entity for a double quote ("). Servers use this to escape quotes in HTML content to avoid breaking the structure of tags. When writing regex to match this, you need to use the literal string " instead of " in your pattern. For example, if the meta tag uses " for attribute quotes, your regex should look for name="bid_kid" instead of name="bid_kid".

• Always test your regex against the actual HTML response you receive—this helps catch edge cases like escaped characters or unexpected formatting.
• If bid_kid is part of a JSON object inside a script, consider using Gatling's jsonPath extractor instead of regex for more reliability.
• Use find or findAll with your regex if you expect multiple matches, but by default, regex grabs the first match (which is usually what you want for a single token).

内容的提问来源于stack exchange，提问作者Magnus Jensen