How to escape JMeter variables within test components?

Question

I've a variable foobar defined with the value my_value. When the sequence ${foobar} appears within a test component, it is converted into my_value. How can we stop this conversion?

Some examples that do not work:

• ${foobar} (output is my_value)

• \${foobar} (output is input)

• \\${foobar} (output is \my_value)

• \\\${foobar} (output is input)

• $\{foobar} (output is input)

• \$\{foobar} (output is input)

• \\$\{foobar} (output is input)

• \\\$\{foobar} (output is input)

• $\\{foobar} (output is input)

• \$\\{foobar} (output is input)

• \\$\\{foobar} (output is input)

• \\\$\\{foobar} (output is input)

• $\\\{foobar} (output is input)

• \$\\\{foobar} (output is input)

• \\$\\\{foobar} (output is input)

• \\\$\\\{foobar} (output is input)

• \$\{foobar\} (output is input)

None of the inputs above produces the output ${foobar}. How can we escape the sequence ${foobar} to avoid it being converted into my_value?

(Note: I know that using BSF string works, e.g. ${__javaScript("\$foobar")} but that's an extremely hacky (and messy) fix.)

Answer 1

Actually there is no way to do it differently. Another non-scripting option is replacing 1st character (which is $) with equivalent provided via __char() function like:

    ${__char(36)}{foobar}=${foobar}

Also it is not very recommended to use JavaScript (or any other languages except groovy) for scripting as it may become the bottleneck in case of severe loads and ruin your test. So consider using JSR223 Test Elements and make sure that you select "groovy" language in the dropdown.

See Beanshell vs JSR223 vs Java JMeter Scripting: The Performance-Off You've Been Waiting For! article for more details, different scripting engines performance benchmarks, groovy engine installation instructions and scripting best practices.

Answer 2

This is the functionality of JMeter (like any other tool) to pass value of parameter when it's related variable is encountered with correct syntax. Even if I use some other tool and syntax of tool says when you encounter '${Firstname}' variable then replace it with its value as bound by the user, it will replace the same no matter whether I want to replace it at that time or not.

But for your issue, you can implement this with the help of 2 variables (if there is a possibility in your script) e.g. use variable ${foobar1} and ${foobar2} and bind only variable ${foobar1} with a CSV file of other parameter but don't bind ${foobar2} with any parameter. Now, use ${foobar1} only at those places in your script where you want to replace it with its value and at other places use ${foobar2}, in this way when your script is executed ${foobar1} will be replaced with the value and ${foobar2} will be used as it is (i.e. your input will be output). When variable is not bound to any value then it will passed as it is to the script during execution in JMeter.

Another way is to use two variables as mentioned above and then bind ${foobar2} with the value ${foobar} i.e. the value of second variable should be ${foobar} in your CSV, so when script is executed ${foobar1} is replaced with actual value and ${foobar2} will be replaced with value ${foobar}.

One more work around for this is possible if you have to achieve this configuration for different HTTP Requests as shown below.

For example: This is what you want to achieve

Then, you need to use the CSV file (variables) only within the HTTP Request scope as shown below.

Note: This will increase your effort, but as said these are the work-arounds which will provide you what you want to achieve without using BSF.