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Class PostContentCommand

Sends user input (text or speech) to Amazon Lex. Clients use this API to send text and audio requests to Amazon Lex at runtime. Amazon Lex interprets the user input using the machine learning model that it built for the bot.

The PostContent operation supports audio input at 8kHz and 16kHz. You can use 8kHz audio to achieve higher speech recognition accuracy in telephone audio applications.

In response, Amazon Lex returns the next message to convey to the user. Consider the following example messages:

  • For a user input "I would like a pizza," Amazon Lex might return a response with a message eliciting slot data (for example, PizzaSize): "What size pizza would you like?".

  • After the user provides all of the pizza order information, Amazon Lex might return a response with a message to get user confirmation: "Order the pizza?".

  • After the user replies "Yes" to the confirmation prompt, Amazon Lex might return a conclusion statement: "Thank you, your cheese pizza has been ordered.".

Not all Amazon Lex messages require a response from the user. For example, conclusion statements do not require a response. Some messages require only a yes or no response. In addition to the message, Amazon Lex provides additional context about the message in the response that you can use to enhance client behavior, such as displaying the appropriate client user interface. Consider the following examples:

  • If the message is to elicit slot data, Amazon Lex returns the following context information:

    • x-amz-lex-dialog-state header set to ElicitSlot

    • x-amz-lex-intent-name header set to the intent name in the current context

    • x-amz-lex-slot-to-elicit header set to the slot name for which the message is eliciting information

    • x-amz-lex-slots header set to a map of slots configured for the intent with their current values

  • If the message is a confirmation prompt, the x-amz-lex-dialog-state header is set to Confirmation and the x-amz-lex-slot-to-elicit header is omitted.

  • If the message is a clarification prompt configured for the intent, indicating that the user intent is not understood, the x-amz-dialog-state header is set to ElicitIntent and the x-amz-slot-to-elicit header is omitted.

In addition, Amazon Lex also returns your application-specific sessionAttributes. For more information, see Managing Conversation Context.


Use a bare-bones client and the command you need to make an API call.

import { LexRuntimeServiceClient, PostContentCommand } from "@aws-sdk/client-lex-runtime-service"; // ES Modules import
// const { LexRuntimeServiceClient, PostContentCommand } = require("@aws-sdk/client-lex-runtime-service"); // CommonJS import
const client = new LexRuntimeServiceClient(config);
const command = new PostContentCommand(input);
const response = await client.send(command);

PostContentCommandInput for command's input shape.


PostContentCommandOutput for command's response shape.


config for LexRuntimeServiceClient's config shape.







Readonly input

input: PostContentCommandInput

Readonly middlewareStack

middlewareStack: IMiddlewareStack<PostContentCommandInput, PostContentCommandOutput>


Static getEndpointParameterInstructions