Strange behavior of my simple API

[rex]

I'm trying a simple API, and I have a strange behavior with the result.
The result is JSON formatted, the data come from a DB query.
The result has unwanted escape characters:

"{"type":[ {"sensor":"temperature", "unit":"celsius"}, {"sensor":"humidity", "unt":"relative"} ]}"

To be sure that this isn't due to the DB response, I've modified the payload. Now it's static.
So, i'm sure, the msg.payload, passed to http request, is without escape characters:
{"type":[ {"sensor":"temperature", "unit":"celsius"}, {"sensor":"humidity", "unt":"relative"} ]}
checked with debug node, but te response from http request is still with escape characters.
How to remove them?

Thanks, Fabrizio

[Colin]

Do you mean the double quotes round the outside? Can you feed the response into a debug node and screenshot what you see and paste it here so we can fully understand what you mean please.

[rex]

This is te payload of http request:

and this is the result:

The result adds \ as escape character.

And also the headres of the http response:

[knolleary]

This happens because your property msg.payload.d_type is a JSON encoded string. That means it stays as a String when msg.payload is itself JSON encoded and returned.

Add a JSON node and configure it to parse msg.payload.d_type to an object before the HTTP Response node.

[rex]

Thanks knolleary for your suggestion.

I had already done it, but without results.

Here the modified flow with the added JSON node.

Even changing the action, I have the same result.

[knolleary]

In your original screenshot, msg.payload was an object with a property called d_type that needed parsing.

In this most recent screenshot, msg.payload is an array of objects. That means the path to the element you need to convert is msg.payload[0].d_type.

[rex]

Ok, sorry, my mistake. I've forgotten the array index. payload[0].d_type
Now a new question: how to apply to all elements of the array?
Thanks.

[knolleary]

One option would be to add a Split node before the JSON node and a Join node afterwards. Use their default configuration and change the JSON node back to msg.payload.d_type.

Another option would be to replace the JSON node with a Function node:

msg.payload = msg.payload.map(function(v) {
   v.d_type = JSON.parse(v.d_type);
   return v;
});
return msg;

[rex]

@knolleary

node afterwards. Use their

I've adopted the second solution. I'm a bungler, so it has taken me more time than really need, but it works.
Thanks,
Fabrizio