Not able to parse value using Regular Expression Extractor in JMETER

Question

I have a HTTP Response from JMETER as :

[{"Id":null,"Message":"2578W,","IsError":false}]

I need to pass the message "2578W" into the next HTTP request. I am using the Regular Expression Extractor in JMETER. and passing the values as: Apply to Main Sample and sub-sample

Field to Check : Body
Reference Name: ${Message}
Regular Expression: [{"Id":null,"Message":"(.*?),","IsError":false}]
Match No. 1
Default Value: Not found

Answer 1

You need to escape these symbols [] with backslashes as they are Regular Expressions Meta Characters representing character classes

So I would recommend amending your Regular Expression to look like:

\[{"Id":null,"Message":"(.+?),","IsError":false}\]

Don't forget to set "Template" to $1$

See Using RegEx (Regular Expression Extractor) With JMeter article for more details on performing correlation in JMeter tests using regular expressions.

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Given you getting response in JSON format you may find JSON Extractor easier to use, the relevant JSON Path query will be as simple as

$..Message  

Answer 2

Try the folllowing regex:

,"Message":"(.*)",".* 

You can experiment easily on this link. Your original regex matches much much more.