dynamodDB putItem: "UnexpectedParameter: Unexpected key 'L' found in params.Item"
<p>I am attempting to "putItem" a new record into a dynamoDB database but failing on attempts to include an Array in the data.  My params.Item looks like the following:</p>

<pre><code>msg.params.Item = {
    fileName: {S: "filename"}, // database is keyed on filename
    userEmail: {S: "emailaddress"},
    transcription: {S: "text here"},
    features: {L: [ { "relevance": {S: "0.900906"}, "text": {S: "keyword"}} ]}
};
</code></pre>

<p>I repeatedly get the error "UnexpectedParameter: Unexpected key 'L' found in params.Item['features']".  I assume I have somehow formatted the "features" array incorrectly, but I can't figure out where my error is.  I have tried many different incantations of the array.  Any help appreciated as there are shockingly few online examples of working dynamoDB putItem javascript using arrays.</p>

<p>FYI: I am using node.js inside of Node-RED, which may explain the odd code, but I had this working just fine with a Cloudant database before.  Only dynamoDB is choking on this array.</p>