构建检索增强生成（RAG）AI

cd rag-ai-tutorial

npx wrangler dev

export default {
	async fetch(request, env, ctx) {
		const answer = await env.AI.run("@cf/meta/llama-3-8b-instruct", {
			messages: [{ role: "user", content: `What is the square root of 9?` }],
		});

		return new Response(JSON.stringify(answer));
	},
};

npx wrangler deploy

curl https://example.username.workers.dev

{"response":"Answer: The square root of 9 is 3."}

npx wrangler vectorize create vector-index --dimensions=768 --metric=cosine

npx wrangler d1 create database

npx wrangler d1 execute database --remote --command "CREATE TABLE IF NOT EXISTS notes (id INTEGER PRIMARY KEY, text TEXT NOT NULL)"

npx wrangler d1 execute database --remote --command "INSERT INTO notes (text) VALUES ('The best pizza topping is pepperoni')"

import { WorkflowEntrypoint } from "cloudflare:workers";

export class RAGWorkflow extends WorkflowEntrypoint {
	async run(event, step) {
		await step.do("example step", async () => {
			console.log("Hello World!");
		});
	}
}

env.RAG_WORKFLOW.create({ params: { text } });

import { Hono } from "hono";
const app = new Hono();

app.get("/", async (c) => {
	const answer = await c.env.AI.run("@cf/meta/llama-3-8b-instruct", {
		messages: [{ role: "user", content: `What is the square root of 9?` }],
	});

	return c.json(answer);
});

export default app;

import { WorkflowEntrypoint } from "cloudflare:workers";

export class RAGWorkflow extends WorkflowEntrypoint {
	async run(event, step) {
		const env = this.env;
		const { text } = event.payload;

		const record = await step.do(`create database record`, async () => {
			const query = "INSERT INTO notes (text) VALUES (?) RETURNING *";

			const { results } = await env.DB.prepare(query).bind(text).run();

			const record = results[0];
			if (!record) throw new Error("Failed to create note");
			return record;
		});

		const embedding = await step.do(`generate embedding`, async () => {
			const embeddings = await env.AI.run("@cf/baai/bge-base-en-v1.5", {
				text: text,
			});
			const values = embeddings.data[0];
			if (!values) throw new Error("Failed to generate vector embedding");
			return values;
		});

		await step.do(`insert vector`, async () => {
			return env.VECTOR_INDEX.upsert([
				{
					id: record.id.toString(),
					values: embedding,
				},
			]);
		});
	}
}

app.post("/notes", async (c) => {
	const { text } = await c.req.json();
	if (!text) return c.text("Missing text", 400);
	await c.env.RAG_WORKFLOW.create({ params: { text } });
	return c.text("Created note", 201);
});

import { Hono } from "hono";
const app = new Hono();

// Existing post route...
// app.post('/notes', async (c) => { ... })

app.get("/", async (c) => {
	const question = c.req.query("text") || "What is the square root of 9?";

	const embeddings = await c.env.AI.run("@cf/baai/bge-base-en-v1.5", {
		text: question,
	});
	const vectors = embeddings.data[0];

	const vectorQuery = await c.env.VECTOR_INDEX.query(vectors, { topK: 1 });
	let vecId;
	if (
		vectorQuery.matches &&
		vectorQuery.matches.length > 0 &&
		vectorQuery.matches[0]
	) {
		vecId = vectorQuery.matches[0].id;
	} else {
		console.log("No matching vector found or vectorQuery.matches is empty");
	}

	let notes = [];
	if (vecId) {
		const query = `SELECT * FROM notes WHERE id = ?`;
		const { results } = await c.env.DB.prepare(query).bind(vecId).run();
		if (results) notes = results.map((vec) => vec.text);
	}

	const contextMessage = notes.length
		? `Context:\n${notes.map((note) => `- ${note}`).join("\n")}`
		: "";

	const systemPrompt = `When answering the question or responding, use the context provided, if it is provided and relevant.`;

	const { response: answer } = await c.env.AI.run(
		"@cf/meta/llama-3-8b-instruct",
		{
			messages: [
				...(notes.length ? [{ role: "system", content: contextMessage }] : []),
				{ role: "system", content: systemPrompt },
				{ role: "user", content: question },
			],
		},
	);

	return c.text(answer);
});

app.onError((err, c) => {
	return c.text(err);
});

export default app;

import Anthropic from '@anthropic-ai/sdk';

app.get('/', async (c) => {
  // ... Existing code
	const systemPrompt = `When answering the question or responding, use the context provided, if it is provided and relevant.`

	let modelUsed = ""
	let response = null

	if (c.env.ANTHROPIC_API_KEY) {
		const anthropic = new Anthropic({
			apiKey: c.env.ANTHROPIC_API_KEY
		})

		const model = "claude-3-5-sonnet-latest"
		modelUsed = model

		const message = await anthropic.messages.create({
			max_tokens: 1024,
			model,
			messages: [
				{ role: 'user', content: question }
			],
			system: [systemPrompt, notes ? contextMessage : ''].join(" ")
		})

		response = {
			response: message.content.map(content => content.text).join("\n")
		}
	} else {
		const model = "@cf/meta/llama-3.1-8b-instruct"
		modelUsed = model

		response = await c.env.AI.run(
			model,
			{
				messages: [
					...(notes.length ? [{ role: 'system', content: contextMessage }] : []),
					{ role: 'system', content: systemPrompt },
					{ role: 'user', content: question }
				]
			}
		)
	}

	if (response) {
		c.header('x-model-used', modelUsed)
		return c.text(response.response)
	} else {
		return c.text("We were unable to generate output", 500)
	}
})

$ npx wrangler secret put ANTHROPIC_API_KEY

app.delete("/notes/:id", async (c) => {
	const { id } = c.req.param();

	const query = `DELETE FROM notes WHERE id = ?`;
	await c.env.DB.prepare(query).bind(id).run();

	await c.env.VECTOR_INDEX.deleteByIds([id]);

	return c.status(204);
});

import { RecursiveCharacterTextSplitter } from "@langchain/textsplitters";

const text = "Some long piece of text...";

const splitter = new RecursiveCharacterTextSplitter({
	// These can be customized to change the chunking size
	// chunkSize: 1000,
	// chunkOverlap: 200,
});

const output = await splitter.createDocuments([text]);
console.log(output); // [{ pageContent: 'Some long piece of text...' }]

export class RAGWorkflow extends WorkflowEntrypoint {
	async run(event, step) {
		const env = this.env;
		const { text } = event.payload;
		let texts = await step.do("split text", async () => {
			const splitter = new RecursiveCharacterTextSplitter();
			const output = await splitter.createDocuments([text]);
			return output.map((doc) => doc.pageContent);
		});

		console.log(
			"RecursiveCharacterTextSplitter generated ${texts.length} chunks",
		);

		for (const index in texts) {
			const text = texts[index];
			const record = await step.do(
				`create database record: ${index}/${texts.length}`,
				async () => {
					const query = "INSERT INTO notes (text) VALUES (?) RETURNING *";

					const { results } = await env.DB.prepare(query).bind(text).run();

					const record = results[0];
					if (!record) throw new Error("Failed to create note");
					return record;
				},
			);

			const embedding = await step.do(
				`generate embedding: ${index}/${texts.length}`,
				async () => {
					const embeddings = await env.AI.run("@cf/baai/bge-base-en-v1.5", {
						text: text,
					});
					const values = embeddings.data[0];
					if (!values) throw new Error("Failed to generate vector embedding");
					return values;
				},
			);

			await step.do(`insert vector: ${index}/${texts.length}`, async () => {
				return env.VECTOR_INDEX.upsert([
					{
						id: record.id.toString(),
						values: embedding,
					},
				]);
			});
		}
	}
}

npx wrangler deploy