@langchain/core/dist/runnables/passthrough.d.ts

Core LangChain.js abstractions and schemas

import { Runnable, RunnableAssign, RunnableMapLike } from "./base.js";
import { type RunnableConfig } from "./config.js";
type RunnablePassthroughFunc<RunInput = any> = ((input: RunInput) => void) | ((input: RunInput, config?: RunnableConfig) => void) | ((input: RunInput) => Promise<void>) | ((input: RunInput, config?: RunnableConfig) => Promise<void>);
/**
 * A runnable to passthrough inputs unchanged or with additional keys.
 *
 * This runnable behaves almost like the identity function, except that it
 * can be configured to add additional keys to the output, if the input is
 * an object.
 *
 * The example below demonstrates how to use `RunnablePassthrough to
 * passthrough the input from the `.invoke()`
 *
 * @example
 * ```typescript
 * const chain = RunnableSequence.from([
 *   {
 *     question: new RunnablePassthrough(),
 *     context: async () => loadContextFromStore(),
 *   },
 *   prompt,
 *   llm,
 *   outputParser,
 * ]);
 * const response = await chain.invoke(
 *   "I can pass a single string instead of an object since I'm using `RunnablePassthrough`."
 * );
 * ```
 */
export declare class RunnablePassthrough<RunInput = any> extends Runnable<RunInput, RunInput> {
    static lc_name(): string;
    lc_namespace: string[];
    lc_serializable: boolean;
    func?: RunnablePassthroughFunc<RunInput>;
    constructor(fields?: {
        func?: RunnablePassthroughFunc<RunInput>;
    });
    invoke(input: RunInput, options?: Partial<RunnableConfig>): Promise<RunInput>;
    transform(generator: AsyncGenerator<RunInput>, options: Partial<RunnableConfig>): AsyncGenerator<RunInput>;
    /**
     * A runnable that assigns key-value pairs to the input.
     *
     * The example below shows how you could use it with an inline function.
     *
     * @example
     * ```typescript
     * const prompt =
     *   PromptTemplate.fromTemplate(`Write a SQL query to answer the question using the following schema: {schema}
     * Question: {question}
     * SQL Query:`);
     *
     * // The `RunnablePassthrough.assign()` is used here to passthrough the input from the `.invoke()`
     * // call (in this example it's the question), along with any inputs passed to the `.assign()` method.
     * // In this case, we're passing the schema.
     * const sqlQueryGeneratorChain = RunnableSequence.from([
     *   RunnablePassthrough.assign({
     *     schema: async () => db.getTableInfo(),
     *   }),
     *   prompt,
     *   new ChatOpenAI({}).bind({ stop: ["\nSQLResult:"] }),
     *   new StringOutputParser(),
     * ]);
     * const result = await sqlQueryGeneratorChain.invoke({
     *   question: "How many employees are there?",
     * });
     * ```
     */
    static assign<RunInput extends Record<string, unknown> = Record<string, unknown>, RunOutput extends Record<string, unknown> = Record<string, unknown>>(mapping: RunnableMapLike<RunInput, RunOutput>): RunnableAssign<RunInput, RunInput & RunOutput>;
}
export {};