AWS IoT SQL: What happens if I SELECT a JSON payload key that doesn't exist?

Question

Hi,

Let's assume I have the following AWS IoT SQL statement:

`SELECT device, room, value FROM 'topic/subtopic'`

and this runs over the following incoming payload:

```
{
"device": "sensor1",
"value": 34
}
```

Will the resulting output from this SQL statement be:

```
{
"device": "sensor1",
"room": "",
"value": 34
}
```

or

```
{
"device": "sensor1",
"room": "null",
"value": 34
}
```

or:

```
{
"device": "sensor1",
"value": 34
}
```

or something else entirely? Or would the rule raise a parsing error or the like?

Accepted Answer

Hi. It will be:

```
{
  "device": "sensor1",
  "value": 34
}
```

BTW, it's is quite easy to test things like this by creating a rule with a republish action, and then trying it out with the test client in the console.

AWS IoT SQL: What happens if I SELECT a JSON payload key that doesn't exist?

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