Files
n8n/packages/nodes-base/nodes/Evaluation/utils/metricHandlers.ts
2025-12-01 16:38:55 +01:00

362 lines
12 KiB
TypeScript

import {
ChatPromptTemplate,
SystemMessagePromptTemplate,
HumanMessagePromptTemplate,
} from '@langchain/core/prompts';
import type { BaseLanguageModel } from '@langchain/core/language_models/base';
import { distance } from 'fastest-levenshtein';
import { NodeOperationError, nodeNameToToolName } from 'n8n-workflow';
import type {
FieldType,
AssignmentCollectionValue,
IDataObject,
IExecuteFunctions,
} from 'n8n-workflow';
import { z } from 'zod';
import { validateEntry } from '../../Set/v2/helpers/utils';
import {
CORRECTNESS_PROMPT,
CORRECTNESS_INPUT_PROMPT,
HELPFULNESS_PROMPT,
HELPFULNESS_INPUT_PROMPT,
} from '../Evaluation/CannedMetricPrompts.ee';
export const metricHandlers = {
async customMetrics(this: IExecuteFunctions, i: number): Promise<IDataObject> {
const dataToSave = this.getNodeParameter('metrics', i, {}) as AssignmentCollectionValue;
return Object.fromEntries(
(dataToSave?.assignments ?? []).map((assignment) => {
const assignmentValue =
typeof assignment.value === 'number' ? assignment.value : Number(assignment.value);
if (isNaN(assignmentValue)) {
throw new NodeOperationError(
this.getNode(),
`Value for '${assignment.name}' isn't a number`,
{
description: `It's currently '${assignment.value}'. Metrics must be numeric.`,
},
);
}
if (!assignment.name || isNaN(assignmentValue)) {
throw new NodeOperationError(this.getNode(), 'Metric name missing', {
description: 'Make sure each metric you define has a name',
});
}
const { name, value } = validateEntry(
assignment.name,
assignment.type as FieldType,
assignmentValue,
this.getNode(),
i,
false,
1,
);
return [name, value];
}),
);
},
async toolsUsed(this: IExecuteFunctions, i: number): Promise<IDataObject> {
const expectedToolsParam = this.getNodeParameter('expectedTools', i, '');
const expectedToolsString = (expectedToolsParam as string)?.trim() || '';
const expectedTools: string[] = expectedToolsString
? expectedToolsString
.split(',')
.map((tool) => tool.trim())
.filter((tool) => tool !== '')
: [];
const intermediateSteps = this.getNodeParameter('intermediateSteps', i, {}) as Array<{
action: { tool: string };
}>;
if (!expectedTools || expectedTools.length === 0) {
throw new NodeOperationError(this.getNode(), 'Expected tool name missing', {
description:
'Make sure you add at least one expected tool name (comma-separated if multiple)',
});
}
if (!intermediateSteps || !Array.isArray(intermediateSteps)) {
throw new NodeOperationError(this.getNode(), 'Intermediate steps missing', {
description:
"Make sure to enable returning intermediate steps in your agent node's options, then map them in here",
});
}
// Convert user-entered tool names to the format used in intermediate steps (case-insensitive)
const normalizedExpectedTools = expectedTools.map((tool) =>
nodeNameToToolName(tool).toLowerCase(),
);
// Calculate individual tool usage (1 if used, 0 if not used)
const toolUsageScores = normalizedExpectedTools.map((normalizedTool) => {
return intermediateSteps.some((step) => {
// Handle malformed intermediate steps gracefully
if (!step || !step.action || typeof step.action.tool !== 'string') {
return false;
}
return step.action.tool.toLowerCase() === normalizedTool;
})
? 1
: 0;
});
// Calculate the average of all tool usage scores
const averageScore =
toolUsageScores.reduce((sum: number, score: number) => sum + score, 0) /
toolUsageScores.length;
const metricName = this.getNodeParameter('options.metricName', i, 'Tools Used') as string;
return {
[metricName]: averageScore,
};
},
async categorization(this: IExecuteFunctions, i: number): Promise<IDataObject> {
const expectedAnswer = (this.getNodeParameter('expectedAnswer', i, '') as string)
.toString()
.trim();
const actualAnswer = (this.getNodeParameter('actualAnswer', i, '') as string).toString().trim();
if (!expectedAnswer) {
throw new NodeOperationError(this.getNode(), 'Expected answer is missing', {
description: 'Make sure to fill in an expected answer',
});
}
if (!actualAnswer) {
throw new NodeOperationError(this.getNode(), 'Actual answer is missing', {
description: 'Make sure to fill in an actual answer',
});
}
const metricName = this.getNodeParameter('options.metricName', i, 'Categorization') as string;
return {
[metricName]: expectedAnswer === actualAnswer ? 1 : 0,
};
},
async stringSimilarity(this: IExecuteFunctions, i: number): Promise<IDataObject> {
const expectedAnswer = (this.getNodeParameter('expectedAnswer', i, '') as string)
.toString()
.trim();
const actualAnswer = (this.getNodeParameter('actualAnswer', i, '') as string).toString().trim();
if (!expectedAnswer) {
throw new NodeOperationError(this.getNode(), 'Expected answer is missing', {
description: 'Make sure to fill in an expected answer',
});
}
if (!actualAnswer) {
throw new NodeOperationError(this.getNode(), 'Actual answer is missing', {
description: 'Make sure to fill in an actual answer',
});
}
const metricName = this.getNodeParameter(
'options.metricName',
i,
'String similarity',
) as string;
const editDistance = distance(expectedAnswer, actualAnswer);
const longerStringLength = Math.max(expectedAnswer.length, actualAnswer.length);
const similarity = longerStringLength === 0 ? 1 : 1 - editDistance / longerStringLength;
return {
[metricName]: similarity,
};
},
async helpfulness(this: IExecuteFunctions, i: number): Promise<IDataObject> {
const userQuery = (this.getNodeParameter('userQuery', i, '') as string).toString().trim();
const actualAnswer = (this.getNodeParameter('actualAnswer', i, '') as string).toString().trim();
if (!userQuery) {
throw new NodeOperationError(this.getNode(), 'User query is missing', {
description: 'Make sure to fill in the user query in the User Query field',
});
}
if (!actualAnswer) {
throw new NodeOperationError(this.getNode(), 'Response is missing', {
description: 'Make sure to fill in the response to evaluate in the Response field',
});
}
// Get the connected LLM model
const llm = (await this.getInputConnectionData('ai_languageModel', 0)) as BaseLanguageModel;
if (!llm) {
throw new NodeOperationError(this.getNode(), 'No language model connected', {
description: 'Connect a language model to the Model input to use the helpfulness metric',
});
}
// Get the system prompt and input prompt template, using defaults if not provided
const systemPrompt = this.getNodeParameter('prompt', i, HELPFULNESS_PROMPT) as string;
const inputPromptTemplate = this.getNodeParameter(
'options.inputPrompt',
i,
HELPFULNESS_INPUT_PROMPT[0],
) as string;
// Define the expected response schema
const responseSchema = z.object({
extended_reasoning: z
.string()
.describe('detailed step-by-step analysis of the response helpfulness'),
reasoning_summary: z.string().describe('one sentence summary of the response helpfulness'),
score: z
.number()
.int()
.min(1)
.max(5)
.describe('integer from 1 to 5 representing the helpfulness score'),
});
// Create LangChain prompt templates
const systemMessageTemplate = SystemMessagePromptTemplate.fromTemplate('{systemPrompt}');
const humanMessageTemplate = HumanMessagePromptTemplate.fromTemplate(inputPromptTemplate);
// Create the chat prompt template
const chatPrompt = ChatPromptTemplate.fromMessages([
systemMessageTemplate,
humanMessageTemplate,
]);
// Create chain with structured output
if (!llm.withStructuredOutput) {
throw new NodeOperationError(
this.getNode(),
'Language model does not support structured output',
{
description:
'The connected language model does not support structured output. Please use a compatible model.',
},
);
}
const chain = chatPrompt.pipe(
llm.withStructuredOutput<z.infer<typeof responseSchema>>(responseSchema),
);
try {
const response = await chain.invoke({
systemPrompt,
user_query: userQuery,
actual_answer: actualAnswer,
});
const metricName = this.getNodeParameter('options.metricName', i, 'Helpfulness') as string;
// Return the score as the main metric
return {
[metricName]: response.score,
};
} catch (error) {
throw new NodeOperationError(this.getNode(), 'Failed to evaluate helpfulness', {
description: `Error from language model: ${error instanceof Error ? error.message : String(error)}`,
});
}
},
async correctness(this: IExecuteFunctions, i: number): Promise<IDataObject> {
const expectedAnswer = (this.getNodeParameter('expectedAnswer', i, '') as string)
.toString()
.trim();
const actualAnswer = (this.getNodeParameter('actualAnswer', i, '') as string).toString().trim();
if (!expectedAnswer) {
throw new NodeOperationError(this.getNode(), 'Expected answer is missing', {
description: 'Make sure to fill in an expected answer',
});
}
if (!actualAnswer) {
throw new NodeOperationError(this.getNode(), 'Actual answer is missing', {
description: 'Make sure to fill in an actual answer',
});
}
// Get the connected LLM model
const llm = (await this.getInputConnectionData('ai_languageModel', 0)) as BaseLanguageModel;
if (!llm) {
throw new NodeOperationError(this.getNode(), 'No language model connected', {
description: 'Connect a language model to the Model input to use the correctness metric',
});
}
// Get the system prompt and input prompt template, using defaults if not provided
const systemPrompt = this.getNodeParameter('prompt', i, CORRECTNESS_PROMPT) as string;
const inputPromptTemplate = this.getNodeParameter(
'options.inputPrompt',
i,
CORRECTNESS_INPUT_PROMPT[0],
) as string;
// Define the expected response schema
const responseSchema = z.object({
extended_reasoning: z
.string()
.describe('detailed step-by-step analysis of factual accuracy and similarity'),
reasoning_summary: z.string().describe('one sentence summary focusing on key differences'),
score: z
.number()
.int()
.min(1)
.max(5)
.describe('integer from 1 to 5 representing the similarity score'),
});
// Create LangChain prompt templates
const systemMessageTemplate = SystemMessagePromptTemplate.fromTemplate('{systemPrompt}');
const humanMessageTemplate = HumanMessagePromptTemplate.fromTemplate(inputPromptTemplate);
// Create the chat prompt template
const chatPrompt = ChatPromptTemplate.fromMessages([
systemMessageTemplate,
humanMessageTemplate,
]);
// Create chain with structured output
if (!llm.withStructuredOutput) {
throw new NodeOperationError(
this.getNode(),
'Language model does not support structured output',
{
description:
'The connected language model does not support structured output. Please use a compatible model.',
},
);
}
const chain = chatPrompt.pipe(
llm.withStructuredOutput<z.infer<typeof responseSchema>>(responseSchema),
);
try {
const response = await chain.invoke({
systemPrompt,
actual_answer: actualAnswer,
expected_answer: expectedAnswer,
});
const metricName = this.getNodeParameter('options.metricName', i, 'Correctness') as string;
// Return the score as the main metric
return {
[metricName]: response.score,
};
} catch (error) {
throw new NodeOperationError(this.getNode(), 'Failed to evaluate correctness', {
description: `Error from language model: ${error instanceof Error ? error.message : String(error)}`,
});
}
},
};