How to properly set variables so you can use variables from prompts in dataset

[zachkamran]

Describe your question

I am using langfuse prompt feature. I see my reqeuests in the linked generations, but when i try to create a dataset with them it tells me I am missing variables. I checked the docs thouroughly and had claude investigate but I can't figure out how to properly generate so that the variables are saved in the generation and can be reused later.

Langfuse Cloud or Self-Hosted?

Langfuse Cloud

If Self-Hosted

No response

If Langfuse Cloud

https://us.cloud.langfuse.com/project/cmn9fd7js05hpad079jsww0t7/traces

SDK and integration versions

No response

Pre-Submission Checklist

• I have checked for existing issues/discussions and consulted Langfuse AI.

[inkeep-ai-assistant[bot]]

When creating a dataset from generations that use prompts with variables, the dataset items must have input keys that exactly match the variable names in your prompt at the top level(1).

For example, if your prompt uses {{input}}, each dataset item's input JSON must have a top-level "input" key—no nesting or alternate naming(1).

Key requirements:

1. Every dataset item's input JSON must contain all required keys at the top level that match your prompt variables(1)
2. These variables must be referenced in the main prompt template, not just in imported/composed prompts(1)
3. The variable names must match exactly between your prompt and dataset items(1)

Example structure:

If your prompt contains:

As a {{criticLevel}} movie critic, do you like {{movie}}?

(2)

Your dataset item input must be structured like:

{
  "criticLevel": "expert",
  "movie": "Dune 2"
}

Common issues:

• Variables only present in composed/imported prompts but not referenced at the top level of the main prompt template will cause this error(1)
• Nested keys or alternate naming in dataset items won't match the expected variable structure(1)

Workarounds:

• Surface all needed variables in the main prompt template(1)
• Ensure dataset item input JSON has all required keys at the top level(1)
• For composed prompts, reference variables in the parent prompt, not just child prompts(1)

A fix for variable recognition in composed prompts is available in OSS release >v3.112.0(1). If you're on Langfuse Cloud, this should already be resolved for most cases(1).

📚 Sources:

1. bug: Prompt experiments incorrectly report "No dataset item contains any variables" even when variables exist in prompt
2. Variables in Prompts

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Have another question? Just tag @inkeep.

[CodeCLS]

Hi @zachkamran, was Inkeep's reply helpful?