Zig

Download a File from a SharePoint Documents Library

See more SharePoint Examples

This example shows how to use Chilkat's HttpCurl class to download a file from the root of a SharePoint Documents document library. The example demonstrates how HttpCurl automatically resolves the SharePoint site name to a site ID, finds the drive ID for the Documents library, locates the file by name, and then downloads the file content using Microsoft Graph.

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 downloads a file named "hamlet.json" from the root of the SharePoint
    // Documents document library.
    //
    // The example demonstrates how HttpCurl can automatically resolve all of the
    // information needed to locate and download a file:
    //
    //   site_name            -> site_id
    //   site_id              -> document_library_id
    //   document_library_id  -> file_id
    //   file_id              -> file content
    //
    // The application only provides the SharePoint site name and the desired
    // filename.  HttpCurl automatically executes the required Microsoft Graph
    // requests to obtain the remaining values.

    success = false;

    // --------------------------------------------------------------------------------------------------------
    // Before running this example, create an Azure App Registration and grant it
    // the Microsoft Graph permissions required to access SharePoint.
    //
    // The application will authenticate using OAuth2 Client Credentials.
    // See:
    // How to Create SharePoint App Registration for OAuth 2.0 Client Credentials
    // --------------------------------------------------------------------------------------------------------

    // Build a JSON authentication configuration.
    // HttpCurl will use this information to automatically obtain OAuth2 access tokens.
    const json_auth = try chilkat.JsonObject.init();
    defer json_auth.deinit();

    // Enable secret lookup.
    //
    // Instead of hard-coding sensitive values such as the client ID,
    // client secret, and token endpoint, secret specification strings
    // are used.  Chilkat automatically retrieves the actual values from
    // Windows Credential Manager (Windows) or Apple Keychain (macOS).
    //
    // See:
    // Secret Specification Strings
    json_auth.setEnableSecrets(true);

    success = if (json_auth.updateString("oauth2.client_id", "!!sharepoint|oauth2|client_id")) true else |_| false;
    if (success) {
        success = if (json_auth.updateString("oauth2.client_secret", "!!sharepoint|oauth2|client_secret")) true else |_| false;
    }

    if (success) {
        success = if (json_auth.updateString("oauth2.token_endpoint", "!!sharepoint|oauth2|token_endpoint")) true else |_| false;
    }

    if (!success) {
        std.debug.print("{s}\n", .{try json_auth.getLastErrorText(alloc)});
        return;
    }

    // Request Microsoft Graph permissions that were granted to the application.
    json_auth.updateString("oauth2.scope", "https://graph.microsoft.com/.default") catch {};

    // ---------------------------------------------------------------------------------------------------

    const curl = try chilkat.HttpCurl.init();
    defer curl.deinit();

    // Associate the OAuth2 configuration with HttpCurl.
    //
    // When the request is executed, Chilkat automatically obtains an access token
    // if needed and adds the Authorization: Bearer header to the HTTP request.
    curl.setAuth(json_auth) catch {};

    // Define values that are already known.
    //
    // These variables are referenced in curl commands using
    // {{variable_name}} substitution syntax.
    curl.setVar("sharepoint_hostname", "example.sharepoint.com");
    curl.setVar("site_name", "test");

    // The first step is to obtain the Microsoft Graph site ID.
    //
    // The application only knows the SharePoint site name, so define
    // a function that can retrieve the site information.
    curl.addFunction("getSite", "GET https://graph.microsoft.com/v1.0/sites/root:/sites/{{site_name}}") catch {};

    // Extract the site's ID and store it in the HttpCurl variable named site_id.
    curl.addOutput("getSite", "id", "site_id") catch {};

    // The next step is to find the Documents document library.
    //
    // Microsoft Graph refers to document libraries as "drives".
    curl.addFunction("getDrives", "GET https://graph.microsoft.com/v1.0/sites/{{site_id}}/drives") catch {};

    // Search the returned drives for the one named "Documents"
    // and save its drive ID in the document_library_id variable.
    curl.addOutput2("getDrives", "value", "name", "Documents", true, "id", "document_library_id") catch {};

    // Now list the contents of the Documents document library.
    curl.addFunction("getFiles", "GET https://graph.microsoft.com/v1.0/sites/{{site_id}}/drives/{{document_library_id}}/root/children") catch {};

    // Search the returned files for an item named "hamlet.json"
    // and save its Microsoft Graph item ID in the file_id variable.
    curl.addOutput2("getFiles", "value", "name", "hamlet.json", true, "id", "file_id") catch {};

    // This is the target request.
    //
    // GET -L https://graph.microsoft.com/v1.0/drives/{{document_library_id}}/items/{{file_id}}/content
    //
    // The /content endpoint returns the actual contents of the file.
    //
    // The -L option instructs HttpCurl to follow the redirect returned by
    // Microsoft Graph.  The Graph API typically responds with a redirect
    // to the actual file download URL.
    const curl_command = "GET -L https://graph.microsoft.com/v1.0/drives/{{document_library_id}}/items/{{file_id}}/content";

    // Execute the request.
    //
    // HttpCurl examines the target request and determines that both
    // document_library_id and file_id are required.
    //
    // To obtain these values, it automatically builds and executes
    // the following dependency chain:
    //
    //   1) getSite      -> site_id
    //   2) getDrives    -> document_library_id
    //   3) getFiles     -> file_id
    //   4) download     -> file content
    //
    // The final response returned by DoYourThing is the downloaded
    // file content from the target request.
    curl.doYourThing(curl_command) catch {
        std.debug.print("{s}\n", .{try curl.getLastErrorText(alloc)});
        return;
    };

    // A successful Graph response should return HTTP 200.
    // Any other status code typically indicates an authentication,
    // permission, site lookup, document library lookup, or file lookup error.
    const status_code = curl.getStatusCode();
    if (status_code != 200) {
        std.debug.print("{s}\n", .{try curl.getResponseBodyStr(alloc)});
        std.debug.print("status code = {d}\n", .{status_code});
        return;
    }

    // The response body contains the contents of the downloaded file.
    const sb_file_contents = try chilkat.StringBuilder.init();
    defer sb_file_contents.deinit();
    curl.getResponseSb(sb_file_contents) catch {};

    // Optionally save the downloaded content to a local file.
    //
    // The third argument controls whether the file is appended.
    // Passing ckfalse causes the file to be overwritten if it already exists.
    sb_file_contents.writeFile("c:/temp/hamlet.json", "utf-8", false) catch {
        std.debug.print("{s}\n", .{try sb_file_contents.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("Success.\n", .{});
}