topic Re: transmettre un JSON en input pour un tRestClient in Talend Studio

transmettre un JSON en input pour un tRestClient

anyxs — Tue, 12 May 2026 15:04:30 GMT

Bonjour,

Je suis nouvelle sur Talend Open Studio et je rencontre une difficulté avec le composant tRESTClient.

Je souhaiterais savoir quelle est la bonne méthode pour transmettre un JSON contenant deux valeurs en input (par exemple username et password) dans une requête POST.

Quelle est la bonne pratique recommandée pour construire et envoyer ce type de JSON avec tRESTClient ?

Merci d’avance pour votre aide.

Re: transmettre un JSON en input pour un tRestClient

Rahul_Kale — Wed, 13 May 2026 13:25:19 GMT

Hello anyxs,

Thank you for reaching out to the Qlik community.

In tRESTClient, don’t manually concatenate JSON in the body. Instead: Prepare JSON with tMap / schema

You can configure tRESTClient

Method: POST
Body type: String
Use column: select your JSON column
HTTP Header:Content-Type = application/json

Recommended approach

Use tWriteJSONField → tRESTClient`
(avoids string errors and ensures valid JSON formatting)

In short, you can generate JSON using schema-based components, then pass it as a body string with application/json header.

Re: transmettre un JSON en input pour un tRestClient

anyxs — Wed, 13 May 2026 14:31:20 GMT

Thank you for your answer!

I am trying to follow your recommended approach using tWriteJSONField → tRESTClient, but I am struggling with the tWriteJSONField configuration.

I have:
- A tFixedFlowInput with 3 columns: username (String), password (String), body (String)
- The JSON structure configured with username and password mapped under rootTag

However, I get the following error:
"Le paramètre (Boucle JSON) doit avoir au moins une valeur"
(The JSON Loop parameter must have at least one value)

Could you please clarify:
1. How to properly configure the JSON loop in tWriteJSONField?
2. How to configure the "Body type: String" and "Use column" in tRESTClient? I cannot find these fields in my version.

Thank you!

Re: transmettre un JSON en input pour un tRestClient

Rahul_Kale — Thu, 14 May 2026 16:04:13 GMT

You’re very close—your issue comes from how tWriteJSONField expects a loop (array context) and how tRESTClient consumes the body.

1. JSON Loop (tWriteJSONField)

Set: $

Required (one JSON per row), otherwise you get the error.

2. tRESTClient body config

Your version does NOT show “Body type / Use column”
It automatically uses a column named string

So:

Output JSON → jsonBody
In tMap:

jsonBody → string

Final setup

tWriteJSONField
- JSON Loop = $
- Output = jsonBody
tMap
- jsonBody → string
tRESTClient
- POST + JSON

Tip: For simple cases, skip tWriteJSONField and build JSON directly in tMap.