title: How to access EventGrid trigger Event properties in Azure functions input bindings
body: <p>I want to pull in cosmos documents into my azure function based on contents of eventgrid events that it triggers on (python worker runtime). Is it possible to do this?</p>
  
  <p>I have below function.json:</p>
  
  <pre><code>{
    "scriptFile": "__init__.py",
    "bindings": [
      {
        "type": "eventGridTrigger",
        "name": "event",
        "direction": "in"
      },
      {
        "name": "documents",
        "type": "cosmosDB",
        "databaseName": "Metadata",
        "collectionName": "DataElementMappings",
        "sqlQuery" : "SELECT * from c where c.id = {subject}",
        "connectionStringSetting": "MyCosmosDBConnectionString",
        "direction": "in"
    }
    ]
  }
  </code></pre>
  
  <p>I want to use properties of the event in the query for the cosmos input binding. I tried it with subject here. It fails with:</p>
  
  <p>[6/4/2020 5:34:45 PM] System.Private.CoreLib: Exception while executing function: Functions.orch_taskchecker. System.Private.CoreLib: The given key 'subject' was not present in the dictionary.</p>
  
  <p>So I am not using the right key name. The only key I got to work is {data} but unfortunately I was not able to access any properties inside the event data using the syntax {data.property} as it says in the docs. I would expect all of the event grid schema keys to be available to use in other bindings since an event is a JSON payload. I got none of them to work, e.g. eventTime, event_type, topic, etc. </p>
  
  <p>Since I saw an example of the same idea for storage queues and they used for example {Queue.id} I tried things like {Event.subject}, {EventGridEvent.subject} all to no avail.</p>
  
  <p>Nowhere in the docs can I find samples of event grid trigger data being used in other bindings. Can this be achieved?</p>