B4X
Download a SharePoint File by Path using HttpCurl

This example shows how to use Chilkat's HttpCurl class to download a file from SharePoint when the file path within the document library is already known. The example uses Microsoft Graph to automatically resolve the SharePoint site name to a site ID, find the drive ID for the Documents document library, and then download the file directly by path using the Graph root:/path:/content syntax.
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Dim success As Boolean = False

'  This example downloads a file from a SharePoint Documents document library
'  when the file's path within the library is already known.
'  
'  The file downloaded in this example is:
'  
'    images/sea_creatures/starfish.jpg
'  
'  Unlike the previous example  that searched for a file by name and obtained
'  its Microsoft Graph item ID, this example uses the Graph path-based API.
'  
'  The example demonstrates how HttpCurl automatically resolves:
'  
'    site_name  -> site_id
'    site_id    -> document_library_id
'  
'  and then uses the known file path to download the file directly.

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.
Dim jsonAuth As ChilkatJsonObject
jsonAuth.Initialize

'  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
jsonAuth.EnableSecrets = True

success = jsonAuth.UpdateString("oauth2.client_id", "!!sharepoint|oauth2|client_id")
If success = True Then
    success = jsonAuth.UpdateString("oauth2.client_secret", "!!sharepoint|oauth2|client_secret")
End If

If success = True Then
    success = jsonAuth.UpdateString("oauth2.token_endpoint", "!!sharepoint|oauth2|token_endpoint")
End If

If success = False Then
    Log(jsonAuth.LastErrorText)
    Return
End If


'  Request Microsoft Graph permissions that were granted to the application.
jsonAuth.UpdateString("oauth2.scope", "https://graph.microsoft.com/.default")

'  ---------------------------------------------------------------------------------------------------

Dim curl As ChilkatHttpCurl
curl.Initialize("curl")

'  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(jsonAuth)

'  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 download request requires a Microsoft Graph site ID.
'  
'  Because the application only knows the SharePoint site name,
'  define a helper function that can retrieve the site information.
curl.AddFunction("getSite", "GET https://graph.microsoft.com/v1.0/sites/root:/sites/{{site_name}}")

'  Extract the site's ID and store it in the HttpCurl variable named site_id.
curl.AddOutput("getSite", "id", "site_id")

'  The download request also requires the drive ID of 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")

'  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")

'  This is the target Microsoft Graph request.
'  
'  GET /sites/{site-id}/drives/{drive-id}/root:/{path-to-file}:/content
'  
'  The path-based API allows a file to be downloaded directly when its
'  location within the document library is known.
'  
'  The -L option causes HttpCurl to follow redirects.
'  Microsoft Graph typically returns a redirect to the actual download URL.
'  
'  The -o option specifies the output filename.
'  The --output-dir option specifies the directory where the downloaded
'  file will be saved.
Dim curlCommand As String = "GET -L --output-dir c:/temp/qa_output -o starfish.jpg https://graph.microsoft.com/v1.0/sites/{{site_id}}/drives/{{document_library_id}}/root:/images/sea_creatures/starfish.jpg:/content"

'  Execute the request.
'  
'  HttpCurl examines the target request and determines that both
'  site_id and document_library_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) download   -> file content
'  
'  The file is streamed directly to the output file specified by
'  the curl command.
success = curl.DoYourThing(curlCommand)
If success = False Then
    Log(curl.LastErrorText)
    Return
End If


'  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.
Dim statusCode As Int = curl.StatusCode
If statusCode <> 200 Then
    Log(curl.ResponseBodyStr)
    Log("status code = " & statusCode)
    Return
End If


'  The file has been downloaded successfully and written to:
'  
'    c:/temp/qa_output/starfish.jpg
'  
Log("Success.")