Zig

Download Photo to a File

See more Facebook Examples

Assuming we have the ID of a Photo, this example demonstrates how to download the photo image data to a file. Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    var success: bool = false;

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // This example assumes a previously obtained an access token
    const oauth2 = try chilkat.OAuth2.init();
    defer oauth2.deinit();
    oauth2.setAccessToken("FACEBOOK-ACCESS-TOKEN");

    const rest = try chilkat.Rest.init();
    defer rest.deinit();

    // Connect to Facebook...
    success = if (rest.connect("graph.facebook.com", 443, true, true)) true else |_| false;
    if (!success) {
        std.debug.print("{s}\n", .{try rest.getLastErrorText(alloc)});
        return;
    }

    // Provide the authentication credentials (i.e. the access key)
    rest.setAuthOAuth2(oauth2) catch {};

    // Assumes we've already obtained a Photo ID.
    const photo_id = "10210199026347451";

    const sb_path = try chilkat.StringBuilder.init();
    defer sb_path.deinit();
    sb_path.append("/v2.7/") catch {};
    sb_path.append(photo_id) catch {};

    // First we're going to get the photo informaton so we can get the URL of the image file data.
    // Select the fields we want.
    // See https://developers.facebook.com/docs/graph-api/reference/photo/
    rest.addQueryParam("fields", "id,album,images") catch {};

    const response_json = rest.fullRequestNoBody(alloc, "GET", try sb_path.getAsString(alloc)) catch {
        std.debug.print("{s}\n", .{try rest.getLastErrorText(alloc)});
        return;
    };

    const json = try chilkat.JsonObject.init();
    defer json.deinit();
    json.setEmitCompact(false);
    json.load(response_json) catch {};

    // Show the JSON in human-readable format.
    std.debug.print("{s}\n", .{try json.emit(alloc)});

    // Get the image URL.
    const image_url = try json.stringOf(alloc, "images[0].source");
    std.debug.print("Downloading from {s}\n", .{image_url});

    const sb_image_url = try chilkat.StringBuilder.init();
    defer sb_image_url.deinit();
    sb_image_url.append(image_url) catch {};

    // Build the output local file path.
    const sb_to_path = try chilkat.StringBuilder.init();
    defer sb_to_path.deinit();
    sb_to_path.append("qa_output/fb") catch {};
    sb_to_path.append(try json.stringOf(alloc, "id")) catch {};
    const b_case_sensitive = false;
    if (sb_image_url.contains(".jpg", b_case_sensitive)) {
        sb_to_path.append(".jpg") catch {};
    } else {
        sb_to_path.append(".png") catch {};
    }

    std.debug.print("Downloading to {s}\n", .{try sb_to_path.getAsString(alloc)});

    // Download using Chilkat HTTP.
    const http = try chilkat.Http.init();
    defer http.deinit();
    success = if (http.download(image_url, try sb_to_path.getAsString(alloc))) true else |_| false;
    if (!success) {
        std.debug.print("{s}\n", .{try http.getLastErrorText(alloc)});
    } else {
        std.debug.print("Downloaded.\n", .{});
    }
}