title: Application Insights Extract Nested CustomDimensions
body: <p>I have some data in Application Insights Analytics that has a dynamic object as a property of custom dimensions. For example:</p>
  
  <pre><code>|        timestamp        |  name   | customDimensions                 | etc |
  |-------------------------|---------|----------------------------------|-----|
  | 2017-09-11T19:56:20.000 | Spinner | {                                | ... |
                                           MyCustomDimension: "hi"
                                           Properties:
                                               context: "ABC"
                                               userMessage: "Some other"
                                        }
  </code></pre>
  
  <p>Does that make sense? So a key/value pair inside of customDimensions.</p>
  
  <p>I'm trying to bring up the <code>context</code> property to be a proper column in the results. So expected would be :</p>
  
  <pre><code>|        timestamp        |  name   | customDimensions                 | context| etc |
  |-------------------------|---------|----------------------------------|--------|-----|
  | 2017-09-11T19:56:20.000 | Spinner | {                                | ABC    | ...
                                           MyCustomDimension: "hi"
                                           Properties:
                                               context: "ABC"
                                               userMessage: "Some other"
                                        }
  </code></pre>
  
  <p>I've tried this:</p>
  
  <pre><code>customEvents | where name == "Spinner" | extend Context = customDimensions.Properties["context"]
  </code></pre>
  
  <p>and this:</p>
  
  <pre><code>customEvents | where name == "Spinner"  | extend Context = customDimensions.Properties.context
  </code></pre>
  
  <p>but neither seem to work. They give me a column at the end named "Context" but the column is empty - no values.</p>
  
  <p>Any ideas?</p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>Added a picture for clarifying the format of the data:</p>
  
  <p><a href="https://i.stack.imgur.com/k1Ec9.png" rel="noreferrer"><img src="https://i.stack.imgur.com/k1Ec9.png" alt="Application Insights Data"></a></p>