AI

useChat()

Allows you to easily create a conversational user interface for your chatbot application. It enables the streaming of chat messages from your AI provider, manages the state for chat input, and updates the UI automatically as new messages are received.

Import

React
Svelte
Vue
Solid
import { useChat } from 'ai/react'

API Signature

Parameters

api?:

string = '/api/chat'
The API endpoint that is called to generate chat responses. It can be a relative path (starting with `/`) or an absolute URL.

id?:

string
An unique identifier for the chat. If not provided, a random one will be generated. When provided, the `useChat` hook with the same `id` will have shared states across components. This is useful when you have multiple components showing the same chat stream.

initialInput?:

string = ''
An optional string for the initial prompt input.

initialMessages?:

Messages[] = []
An optional array of initial chat messages

onToolCall?:

({toolCall: ToolCall}) => void | unknown| Promise<unknown>
Optional callback function that is invoked when a tool call is received. Intended for automatic client-side tool execution. You can optionally return a result for the tool call, either synchronously or asynchronously.

onResponse?:

(response: Response) => void
An optional callback that will be called with the response from the API endpoint. Useful for throwing customized errors or logging

onFinish?:

(message: Message, options: OnFinishOptions) => void
An optional callback function that is called when the completion stream ends.
OnFinishOptions

usage:

CompletionTokenUsage
The token usage for the completion.
CompletionTokenUsage

promptTokens:

number
The total number of tokens in the prompt.

completionTokens:

number
The total number of tokens in the completion.

totalTokens:

number
The total number of tokens generated.

finishReason:

'stop' | 'length' | 'content-filter' | 'tool-calls' | 'error' | 'other' | 'unknown'
The reason why the generation ended.

onError?:

(error: Error) => void
A callback that will be called when the chat stream encounters an error. Optional.

generateId?:

() => string
A custom id generator for messages. Optional.

headers?:

Record<string, string> | Headers
Additional headers to be passed to the API endpoint. Optional.

body?:

any
Additional body object to be passed to the API endpoint. Optional.

credentials?:

'omit' | 'same-origin' | 'include'
An optional literal that sets the mode of credentials to be used on the request. Defaults to same-origin.

sendExtraMessageFields?:

boolean
An optional boolean that determines whether to send extra fields you've added to `messages`. Defaults to `false` and only the `content` and `role` fields will be sent to the API endpoint. If set to `true`, the `name`, `data`, and `annotations` fields will also be sent.

maxSteps?:

number
Maximum number of backend calls to generate a response. A maximum number is required to prevent infinite loops in the case of misconfigured tools. By default, it is set to 1.

streamProtocol?:

'text' | 'data'
An optional literal that sets the type of stream to be used. Defaults to `data`. If set to `text`, the stream will be treated as a text stream.

fetch?:

FetchFunction
Optional. A custom fetch function to be used for the API call. Defaults to the global fetch function.

experimental_prepareRequestBody?:

(options: { messages: Message[]; requestData?: JSONValue; requestBody?: object }) => JSONValue
Experimental (React only). When a function is provided, it will be used to prepare the request body for the chat API. This can be useful for customizing the request body based on the messages and data in the chat.

experimental_throttle?:

number
React only. Custom throttle wait time in milliseconds for the message and data updates. When specified, updates will be throttled using this interval. Defaults to undefined (no throttling).

Returns

messages:

Message[]
The current array of chat messages.
Message

id:

string
The unique identifier of the message.

role:

'system' | 'user' | 'assistant' | 'data'
The role of the message.

content:

string
The content of the message.

createdAt?:

Date
The creation date of the message.

name?:

string
The name of the message.

data?:

JSONValue
Additional data sent along with the message.

annotations?:

Array<JSONValue>
Additional annotations sent along with the message.

toolInvocations?:

Array<ToolInvocation>
An array of tool invocations that are associated with the (assistant) message.
ToolInvocation

state:

'partial-call'
The state of the tool call when it was partially created.

toolCallId:

string
ID of the tool call. This ID is used to match the tool call with the tool result.

toolName:

string
Name of the tool that is being called.

args:

any
Partial arguments of the tool call. This is a JSON-serializable object.
ToolInvocation

state:

'call'
The state of the tool call when it was fully created.

toolCallId:

string
ID of the tool call. This ID is used to match the tool call with the tool result.

toolName:

string
Name of the tool that is being called.

args:

any
Arguments of the tool call. This is a JSON-serializable object that matches the tools input schema.
ToolInvocation

state:

'result'
The state of the tool call when the result is available.

toolCallId:

string
ID of the tool call. This ID is used to match the tool call with the tool result.

toolName:

string
Name of the tool that is being called.

args:

any
Arguments of the tool call. This is a JSON-serializable object that matches the tools input schema.

result:

any
The result of the tool call.

experimental_attachments?:

Array<Attachment>
Additional attachments sent along with the message.
Attachment

name?:

string
The name of the attachment, usually the file name.

contentType?:

string
A string indicating the media type of the file.

url:

string
The URL of the attachment. It can either be a URL to a hosted file or a Data URL.

error:

Error | undefined
An error object returned by SWR, if any.

append:

(message: Message | CreateMessage, options?: ChatRequestOptions) => Promise<string | undefined>
Function to append a message to the chat, triggering an API call for the AI response. It returns a promise that resolves to full response message content when the API call is successfully finished, or throws an error when the API call fails.
ChatRequestOptions

headers:

Record<string, string> | Headers
Additional headers that should be to be passed to the API endpoint.

body:

object
Additional body JSON properties that should be sent to the API endpoint.

data:

JSONValue
Additional data to be sent to the API endpoint.

reload:

() => Promise<string | undefined>
Function to reload the last AI chat response for the given chat history. If the last message isn't from the assistant, it will request the API to generate a new response.

stop:

() => void
Function to abort the current API request.

setMessages:

(messages: Message[] | ((messages: Message[]) => Message[]) => void
Function to update the `messages` state locally without triggering an API call.

input:

string
The current value of the input field.

setInput:

React.Dispatch<React.SetStateAction<string>>
Function to update the `input` value.

handleInputChange:

(event: any) => void
Handler for the `onChange` event of the input field to control the input's value.

handleSubmit:

(event?: { preventDefault?: () => void }, options?: ChatRequestOptions) => void
Form submission handler that automatically resets the input field and appends a user message. You can use the `options` parameter to send additional data, headers and more to the server.
ChatRequestOptions

headers:

Record<string, string> | Headers
Additional headers that should be to be passed to the API endpoint.

body:

object
Additional body JSON properties that should be sent to the API endpoint.

data:

JSONValue
Additional data to be sent to the API endpoint.

allowEmptySubmit?:

boolean
A boolean that determines whether to allow submitting an empty input that triggers a generation. Defaults to `false`.

experimental_attachments?:

FileList | Array<Attachment>
An array of attachments to be sent to the API endpoint.
FileList

A list of files that have been selected by the user using an <input type='file'> element. It's also used for a list of files dropped into web content when using the drag and drop API.
Attachment

name?:

string
The name of the attachment, usually the file name.

contentType?:

string
A string indicating the media type of the file.

url:

string
The URL of the attachment. It can either be a URL to a hosted file or a Data URL.

isLoading:

boolean
Boolean flag indicating whether a request is currently in progress.

data:

JSONValue[]
Data returned from StreamData.

setData:

(data: JSONValue[] | undefined | ((data: JSONValue[] | undefined) => JSONValue[] | undefined)) => void
Function to update the `data` state which contains data from StreamData.

addToolResult:

({toolCallId: string; result: any;}) => void
Function to add a tool result to the chat. This will update the chat messages with the tool result and call the API route if all tool results for the last message are available.

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