createQuestionClassifierNode

workflow.createQuestionClassifierNode() Creates a classification node with input string. It spelled the question, category list, and description into a LLM prompt, and asked the model to return only the category name; if the return value is not in the allowed categories, the node outputs an empty string.

Signature

workflow.createQuestionClassifierNode<
  const Categories extends readonly QuestionClassifierCategory[],
>(
  options: QuestionClassifierNodeOptions<Categories>,
): BaseNode<string, QuestionClassifierOutput<Categories>>

Parameter

Parameter	Type	Description
options	QuestionClassifierNodeOptions<Categories>	Define provider, classifications, user descriptions, and LLM settings.

Options Field

Field	Type	Description
name	string	Node name, default "question-classifier".
provider	LLMProviderSource	provider used for classification. Required.
categories	QuestionClassifierCategory[]	Classification allowed to be returned. The name cannot be duplicated. Required.
userDescription	string	Classification task and user scenario description. Required.
system	string	system prompt. The default value is "You are a strict question classifier.".
settings	LLMCallSettings subset	LLM call parameters; overrides the default temperature: 0, maxOutputTokens: 50.
historyLimit	number	The number of nodes retained in the execution history. The default value is 50.
metadata	WorkflowNodeMetadataInput	The node displays meta information.

Input and output

Name	Type	Description
Input	string	The problem to be classified. An empty string triggers an input validation error.
Output	CategoryName | ""	If the classification is matched, the classification name is returned. If the model returns a non-allowed classification, an empty string is returned.

QuestionClassifierCategory

Field	Description
name	Category name, which is also the exact text that the model must return. Required.
description	The classification description is written to prompt. Required.

LLM Request Content

Fragment	Source	Description
Classification Rules	Fixed template during node execution	Requires that only the category name be returned, no JSON, Markdown, or explanation be returned.
userDescription	options	Business classification description.
categories	options	List allowable classifications and descriptions by serial number.
question	Node Input	User issues.

Example

const classifier = workflow.createQuestionClassifierNode({
  name: "route-question",
  provider: workflow.createLLMProviderRef("default"),
  userDescription: "Classify whether the user is asking a technical question or making casual conversation.",
  categories: [
    { name: "technical", description: "Code, APIs, deployment, or error troubleshooting." },
    { name: "chat", description: "General conversation or a non-technical question." },
  ] as const,
});

const category = await workflow.runNode(classifier, input.message, context);

Error

Situation	Error Type	Description
categories is empty	input_validation	At least one classification is required.
Duplicate Category Name	input_validation	name cannot be repeated.
userDescription or question is empty	input_validation	Required text cannot be empty.
provider call failed	provider_call	Thrown by the provider layer.