title: How to pass JSON into an Azure Function with embedded dynamic content in Azure Data Factory V2
body: <p>In ADFv2 I'm looking up a date and passing it to an Azure Function.  I can pass just the data like so:</p>
  
  <pre><code>@activity('GetLastDateProcessed').output.firstRow.LastDateProcessed
  </code></pre>
  
  <p>However if I embed this into a JSON string like this:</p>
  
  <pre><code>{"lastProcessDate":"@activity('GetLastDateProcessed').output.firstRow.LastDateProcessed"}
  </code></pre>
  
  <p>I get this {"lastProcessDate":"@activity('GetLastDateProcessed').output.firstRow.LastDateProcessed"} instead of {"lastProcessDate":"2019-11-13"} as input into function.</p>
  
  <p>Last I've tried to use a parameter with no success also.</p>
  
  <pre><code>@concat('{"lastProcessDate":"', string(pipeline().parameters.lastProcessDate), '"}')
  </code></pre>
  
  <p>The problem here is the parameter was not set.  I set the parameter like this: </p>
  
  <pre><code>@activity('GetLastDateProcessed').output.firstRow.LastDateProcessed
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/QgDvy.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QgDvy.png" alt="enter image description here"></a>
  However this is a default value and is never dynamically updated.  If I can update this string then the @concat method will work, but haven't been able to figure out how to dynamically update a parameter for the pipeline.  </p>
  
  <p>Another option could be a pipeline variable, but I don't know how to reference the variable.</p>
  
  <p>How do I concat strings together with dynamic content?</p>