docs[patch]: Fix Code in Managing Conversation History

[sarangan12]

Please refer #6246 for the details. The code mentioned in the site gives build error. The code change in this PR fixes the issue.

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[bracesproul]

Thank you!

[bracesproul]

Suggested change

	" const { chat_history } = input as { chat_history: BaseMessage[] };\n",
	" const { chat_history }: { chat_history: BaseMessage[] } = input;\n",

[sarangan12]

@bracesproul The previous suggestion (from unknown to any) will work fine. But, this line will cause the same issue.

Property 'chat_history' is missing in type 'Record<string, any>' but required in type '{ chat_history: BaseMessage[]; }'.ts(2741)
tutorial2_updated.ts(31, 31): 'chat_history' is declared here.

So, I believe we should have it as:

const { chat_history } = input as { chat_history: BaseMessage[] };

[bracesproul]

Jeez you're right, that's annoying. I pushed a commit doing this, which is a little more concise and does not throw any type errors const filterMessages = (input: { chat_history: BaseMessage[] }) => input.chat_history.slice(-10);

[sarangan12]

@bracesproul Actually, even with the new line, the code will still cause build error. But, in a different place. If you add the new line, it will error out in the following lines:

const filterMessages = (input: { chat_history: BaseMessage[] }) => input.chat_history.slice(-10);

  const chain = RunnableSequence.from([
    RunnablePassthrough.assign({
      chat_history: filterMessages,
    }),
    prompt,
    model,
]).pipe(parser);

The following error will be reported:

Type '(input: { chat_history: BaseMessage[]; }) => BaseMessage[]' is not assignable to type 'RunnableLike<Record<string, unknown>, BaseMessage[]>'.
  Type '(input: { chat_history: BaseMessage[]; }) => BaseMessage[]' is not assignable to type 'RunnableFunc<Record<string, unknown>, BaseMessage[]>'.
    Types of parameters 'input' and 'input' are incompatible.
      Property 'chat_history' is missing in type 'Record<string, unknown>' but required in type '{ chat_history: BaseMessage[]; }'.ts(2322)
tutorial2_updated.ts(30, 36): 'chat_history' is declared here.
tutorial2_updated.ts(34, 7): The expected type comes from property 'chat_history' which is declared here on type 'RunnableMapLike<Record<string, unknown>, { chat_history: BaseMessage[]; }>'

[bracesproul]

Thanks for notifying me of this. I'll just push a larger commit adding proper types throughout this entire doc. Give me a few min to do so.