Function createJsonTranslator

typescript/src/typechat.ts:97–163

(model: TypeChatLanguageModel, validator: TypeChatJsonValidator<T>)

 * @returns A `TypeChatJsonTranslator<T>` instance.
 */
export function createJsonTranslator<T extends object>(model: TypeChatLanguageModel, validator: TypeChatJsonValidator<T>): TypeChatJsonTranslator<T> {
    const typeChat: TypeChatJsonTranslator<T> = {
        model,
        validator,
        attemptRepair: true,
        stripNulls: false,
        createRequestPrompt,
        createRepairPrompt,
        validateInstance: success,
        translate
    };
    return typeChat;

    function createRequestPrompt(request: string) {
        return `You are a service that translates user requests into JSON objects of type "${validator.getTypeName()}" according to the following TypeScript definitions:\n` +
            `\`\`\`\n${validator.getSchemaText()}\`\`\`\n` +
            `The following is a user request:\n` +
            `"""\n${request}\n"""\n` +
            `The following is the user request translated into a JSON object with 2 spaces of indentation and no properties with the value undefined:\n`;
    }

    function createRepairPrompt(validationError: string) {
        return `The JSON object is invalid for the following reason:\n` +
            `"""\n${validationError}\n"""\n` +
            `The following is a revised JSON object:\n`;
    }

    async function translate(request: string, promptPreamble?: string | PromptSection[]) {
        const preamble: PromptSection[] = typeof promptPreamble === "string" ? [{ role: "user", content: promptPreamble }] : promptPreamble ?? [];
        let prompt: PromptSection[] = [...preamble, { role: "user", content: typeChat.createRequestPrompt(request) }];
        let attemptRepair = typeChat.attemptRepair;
        while (true) {
            const response = await model.complete(prompt);
            if (!response.success) {
                return response;
            }
            const responseText = response.data;
            const startIndex = responseText.indexOf("{");
            const endIndex = responseText.lastIndexOf("}");
            if (!(startIndex >= 0 && endIndex > startIndex)) {
                return error(`Response is not JSON:\n${responseText}`);
            }
            const jsonText = responseText.slice(startIndex, endIndex + 1);
            let jsonObject;
            try {
                jsonObject = JSON.parse(jsonText) as object;
            }
            catch (e) {
                return error(e instanceof SyntaxError ? e.message : "JSON parse error");
            }
            if (typeChat.stripNulls) {
                stripNulls(jsonObject);
            }
            const schemaValidation = validator.validate(jsonObject);
            const validation = schemaValidation.success ? typeChat.validateInstance(schemaValidation.data) : schemaValidation;
            if (validation.success) {
                return validation;
            }