Rust Input Function Example

Example actor showcasing running a user-provided function in a static-typed compiled language. ## How does it work 1. Reads the input from disk or via Apify API 2. Extracts the page_function string from the input 3. Stores the page_function string to the disk 4. Spawns a system process using cargo to compile the page_function into a dynamic library 5. Dynamically links the library and converts the page_function into a regular Rust function. It must adhere to predefined input/output types. 6. The example code gets HTML from the input provided url and parses it into a document using the Scraper library 7. The user-provided page_function gets the document as an input parameter and returns a JSON Value type using the json macro ## Page function Page function can use a predefined set of Rust libraries, currently only the Scraper library and serde_json for JSON Value type are provided. ### TODO But technically, thanks to dynamic compiling, we can enable users to provide a list of libraries to be used in the page_function. ### Example page_function rust use serde_json::{Value,json}; use scraper::{Html, Selector}; fn selector_to_text(document: &Html, selector: &str) -> Option<String> { document .select(&Selector::parse(selector).unwrap()) .next() .map(|el| el.text().next().unwrap().into() ) } #[no_mangle] pub fn page_function (document: &Html) -> Value { println!("page_function starting"); let title = selector_to_text(&document, "title"); println!("extracted title: {:?}", title); let header = selector_to_text(&document, "h1"); println!("extracted header: {:?}", header); let companies_using_apify = document .select(&Selector::parse(".Logos__container").unwrap()) .next().unwrap() .select(&Selector::parse("img").unwrap()) .map(|el| el.value().attr("alt").unwrap().to_string()) .collect::<Vec<String>>(); println!("extracted companies_using_apify: {:?}", companies_using_apify); let output = json!({ "title": title, "header": header, "companies_using_apify": companies_using_apify, }); println!("inside pageFunction output: {:?}", output); output }