Passing JSON as data, not as string ("Unmarshal type error: expected=models.JSON, got=string"))

[smake]

Hello Community,

I try to create my first App (for listmonk).
The module I am “fighting with” is the one to create a new user. User can have atributes which are stored as a JSON map in Listmonk:
https://listmonk.app/docs/concepts/#attributes

The API endpoint is:
https://listmonk.app/docs/swagger/#/Subscribers

The body should look like this:

{
  "email": "testuser4@xyz.com",
  "name": "Max Mustermann",
  "status": "enabled",
  "preconfirm_subscriptions": true,
  "attribs": 
        {
            "sdfsdfs": "qqqqqabcsfsdfs",
            "keddddy": "adddbc"
        }
}

I want the Create module to have a field where the user can insert the RAW JSON data string.
This is my attempt:

{
	"url": "/subscribers",
	"method": "POST",
	"body": {
		"email": "{{parameters.email}}",
		"name": "{{parameters.name}}",
		"status": "{{parameters.status}}",
		"lists": "{{parameters.lists}}",
		"preconfirm_subscriptions": true,
		"attribs": "{{parameters.attribs}}"
	},
	"response": {
		"output": "{{body}}"
	}
}

But the API always answers with an error:

"Unmarshal type error: expected=models.JSON, got=string, field=attribs, offset=157"

This is the request body:

{
    "name": "Friedrich März",
    "email": "ruh90@gmx.de",
    "lists": [
        2,
        1
    ],
    "status": "enabled",
    "attribs": "{\n\"sdfsdfs\": \"qqqqqabcsfsdfs\",\n\"keddddy\": \"adddbc\"\n}",
    "preconfirm_subscriptions": true
}

I know that I need to convert the JSON raw string in to a data structure - but how?

Thanks - Simon

PS: Hardcoding the data structure in the mappable parameters works:

{
	"url": "/subscribers",
	"method": "POST",
	"body": {
		"email": "{{parameters.email}}",
		"name": "{{parameters.name}}",
		"status": "{{parameters.status}}",
		"lists": "{{parameters.lists}}",
		"preconfirm_subscriptions": true,
		"attribs": 
			{
				"sdfsdfs": "qqqqqabcsfsdfs",
				"keddddy": "adddbc"
			}
	},
	"response": {
		"output": "{{body}}" // Return JSON response body as an output bundle
	}
}

[Henk-Operative]

Hi @smake,

You run into this issue because the input field, where the JSON is placed, is of type ‘text’. Two tips to find the solution:

1. What type of field does a ‘Make an API Call’ use?
2. If the JSON is stringified automatically, what is needed to parse it?

Cheers,
Henk

[smake]

Hi Henk,

thanks for the hint to the Make module. They are using type “any”, but this does not help either.

    {
        "name": "attribs",
        "type": "any",
        "label": "Attributes (JSON)"
    }

{
	"url": "/subscribers",
	"method": "POST",
	"body": {
		"email": "{{parameters.email}}",
		"name": "{{parameters.name}}",
		"status": "{{parameters.status}}",
		"lists": "{{parameters.lists}}",
		"preconfirm_subscriptions": true,
		"attribs": "{{parameters.attribs}}"
	},
	"response": {
		"output": "{{body}}"
	}
}

The request body still contains

    "attribs": "{\n\"sdfsdfs\": \"qqqqqabcsfsdfs\",\n\"keddddy\": \"adddbc\"\n}",

Regarding your second question:

If the JSON is stringified automatically, what is needed to parse it?

You mean the JSON which gets passed into the JSON raw field? Until now, the raw JSON is just created by hand. But… how could that help me? I am not sure if I got your question…

Thanks a lot!
Regards,
Simon

[Henk-Operative]

Hi @smake,

Using ‘any’ as type is just for being correct in syntax, as the field is not strictly used for text. The raw JSON that is added in the field, is automatically escaped and stringified.

Because Make is automatically escaping the raw JSON, you need to parse the JSON before you send the value to the external service. Here is another hint: Make.com - Custom App Documentation

Cheers,
Henk

[smake]

Hi,

thanks again! With that…

{
	"url": "/subscribers",
	"method": "POST",
	"body": {
		"{{...}}": "{{omit(parameters, 'attribs')}}",
		"attribs": "{{createJSON(parameters.attribs)}}"
	},
	"response": {
		"output": "{{body}}"
	}
}

…the JSON string gets now double-escaped, the error remains:

{
    "attribs": "\"{\\n\\\"sdfsdfs\\\": \\\"qqqqqabcsfsdfs\\\",\\n\\\"keddddy\\\": \\\"adddbc\\\"\\n}\"",
...
}

According to the docs, this should work… I hope I did not oversee something very basic… any other idea?

Again, thanks a lot!
Simon

[Henk-Operative]

Hi,

You are almost there, but one small mistake. You are creating JSON now, but you should be parsing it. (read a little further in the docs)

I think you’ve got it after that

Cheers,
Henk

[smake]

Wohoo…
(Always the same: As soon as you do it properly, it works.

Thanks a LOT for pointing me into the right direction. Awesome!
Regards,
Simon