export type FormPrimitive = string | number | boolean | File;
export interface FormObject {
    [key: string]: FormValue;
}
export interface FormArray {
    readonly length: number;
    [key: number]: FormValue;
}
export type FormValue = FormPrimitive | FormObject | FormArray;
/**
 * @description also support files in { [field: string]: File[] | File }
 * One use-case is for FileFieldsInterceptor in nest-client
 */
export declare function jsonToFormData(json: FormObject, formData?: FormData): FormData;
export interface PostFormResponse<T> {
    status: number;
    statusText: string;
    data: Buffer | string | T;
}
export declare function postMultipartFormData<T>(url: string, json: FormObject): Promise<PostFormResponse<T>>;