JMeter setting user defined variable in beanshell not working

Question

I want to overwrite user defined variable in Jmeter in a beanshell. I triead beanshell preprocessor, postprecessor or sample, but nothing worked.

My code:

vars.put("box_user", "mybox");
log.info(vars.get("box_user"));

The output is correct, mybox. But when I use the variable in a sampler later with ${box_user}, the username is not correct. It has the value of the beginning initalization.

What is wrong?

Here is the xml of my jmeter project, tried another variable name, but it is not working:

<?xml version="1.0" encoding="UTF-8"?>
    <jmeterTestPlan version="1.2" properties="2.8" jmeter="2.13 r1665067">
     <hashTree>
    <TestPlan guiclass="TestPlanGui" testclass="TestPlan" testname="Test Plan" enabled="true">
      <stringProp name="TestPlan.comments"></stringProp>
      <boolProp name="TestPlan.functional_mode">false</boolProp>
      <boolProp name="TestPlan.serialize_threadgroups">false</boolProp>
      <elementProp name="TestPlan.user_defined_variables" elementType="Arguments" guiclass="ArgumentsPanel" testclass="Arguments" testname="User Defined Variables" enabled="true">
        <collectionProp name="Arguments.arguments"/>
      </elementProp>
      <stringProp name="TestPlan.user_define_classpath"></stringProp>
    </TestPlan>
    <hashTree>
      <ThreadGroup guiclass="ThreadGroupGui" testclass="ThreadGroup" testname="Thread Group" enabled="true">
        <stringProp name="ThreadGroup.on_sample_error">continue</stringProp>
        <elementProp name="ThreadGroup.main_controller" elementType="LoopController" guiclass="LoopControlPanel" testclass="LoopController" testname="Loop Controller" enabled="true">
          <boolProp name="LoopController.continue_forever">false</boolProp>
          <stringProp name="LoopController.loops">1</stringProp>
        </elementProp>
        <stringProp name="ThreadGroup.num_threads">1</stringProp>
        <stringProp name="ThreadGroup.ramp_time">1</stringProp>
        <longProp name="ThreadGroup.start_time">1441359197000</longProp>
        <longProp name="ThreadGroup.end_time">1441359197000</longProp>
        <boolProp name="ThreadGroup.scheduler">false</boolProp>
        <stringProp name="ThreadGroup.duration"></stringProp>
        <stringProp name="ThreadGroup.delay"></stringProp>
      </ThreadGroup>
      <hashTree>
        <BeanShellSampler guiclass="BeanShellSamplerGui" testclass="BeanShellSampler" testname="BeanShell Sampler" enabled="true">
          <stringProp name="BeanShellSampler.query">vars.put(&quot;user&quot;, &quot;one&quot;);
vars.put(&quot;host&quot;, &quot;localhost&quot;);</stringProp>
          <stringProp name="BeanShellSampler.filename"></stringProp>
          <stringProp name="BeanShellSampler.parameters"></stringProp>
          <boolProp name="BeanShellSampler.resetInterpreter">false</boolProp>
        </BeanShellSampler>
        <hashTree/>
        <JDBCDataSource guiclass="TestBeanGUI" testclass="JDBCDataSource" testname="JDBC Connection Configuration" enabled="true">
          <stringProp name="dataSource">dbcon</stringProp>
          <stringProp name="poolMax">10</stringProp>
          <stringProp name="timeout">10000</stringProp>
          <stringProp name="trimInterval">60000</stringProp>
          <boolProp name="autocommit">true</boolProp>
          <stringProp name="transactionIsolation">DEFAULT</stringProp>
          <boolProp name="keepAlive">true</boolProp>
          <stringProp name="connectionAge">5000</stringProp>
          <stringProp name="checkQuery">Select 1</stringProp>
          <stringProp name="dbUrl">jdbc:postgresql://localhost:5432/box</stringProp>
          <stringProp name="driver">org.postgresql.Driver</stringProp>
          <stringProp name="username">${user}</stringProp>
          <stringProp name="password">pwd</stringProp>
        </JDBCDataSource>
        <hashTree/>
        <JDBCSampler guiclass="TestBeanGUI" testclass="JDBCSampler" testname="JDBC Request" enabled="true">
          <stringProp name="dataSource">dbcon</stringProp>
          <stringProp name="queryType">Select Statement</stringProp>
          <stringProp name="query">SELECT 1</stringProp>
          <stringProp name="queryArguments"></stringProp>
          <stringProp name="queryArgumentsTypes"></stringProp>
          <stringProp name="variableNames"></stringProp>
          <stringProp name="resultVariable"></stringProp>
          <stringProp name="queryTimeout"></stringProp>
          <stringProp name="resultSetHandler">Store as String</stringProp>
        </JDBCSampler>
        <hashTree/>
        <ResultCollector guiclass="ViewResultsFullVisualizer" testclass="ResultCollector" testname="View Results Tree" enabled="true">
          <boolProp name="ResultCollector.error_logging">false</boolProp>
          <objProp>
            <name>saveConfig</name>
            <value class="SampleSaveConfiguration">
              <time>true</time>
              <latency>true</latency>
              <timestamp>true</timestamp>
              <success>true</success>
              <label>true</label>
              <code>true</code>
              <message>true</message>
              <threadName>true</threadName>
              <dataType>true</dataType>
              <encoding>false</encoding>
              <assertions>true</assertions>
              <subresults>true</subresults>
              <responseData>false</responseData>
              <samplerData>false</samplerData>
              <xml>false</xml>
              <fieldNames>false</fieldNames>
              <responseHeaders>false</responseHeaders>
              <requestHeaders>false</requestHeaders>
              <responseDataOnError>false</responseDataOnError>
              <saveAssertionResultsFailureMessage>false</saveAssertionResultsFailureMessage>
              <assertionsResultsToSave>0</assertionsResultsToSave>
              <bytes>true</bytes>
              <threadCounts>true</threadCounts>
            </value>
          </objProp>
          <stringProp name="filename"></stringProp>
        </ResultCollector>
        <hashTree/>
      </hashTree>
    </hashTree>
  </hashTree>
</jmeterTestPlan>

Error is: FATAL: role "${user}" does not exist -> so my variable ist not replace, I dont know why

Answer 1

Any chance that you referring variable in the different Thread Group? If yes, you need to use JMeter Properties instead like:

props.put("box_user", "mybox");

and later use ${__P(box_user,)} to access the value.

It is due to JMeter Variables visibility scope limited to the current Thread Group, as per Functions and Variables chapter:

Properties are not the same as variables. Variables are local to a thread; properties are common to all threads, and need to be referenced using the __P or __property function.

See How to Use Variables in Different Thread Groups. guide for more details.