Classic ASP
Download a File from a SharePoint Documents Library

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.
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<%
success = 0

'  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 = 0

'  --------------------------------------------------------------------------------------------------------
'  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.
set jsonAuth = Server.CreateObject("Chilkat.JsonObject")

'  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 = 1

success = jsonAuth.UpdateString("oauth2.client_id","!!sharepoint|oauth2|client_id")
If (success = 1) Then
    success = jsonAuth.UpdateString("oauth2.client_secret","!!sharepoint|oauth2|client_secret")
End If

If (success = 1) Then
    success = jsonAuth.UpdateString("oauth2.token_endpoint","!!sharepoint|oauth2|token_endpoint")
End If

If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( jsonAuth.LastErrorText) & "</pre>"
    Response.End
End If

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

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

set curl = Server.CreateObject("Chilkat.HttpCurl")

'  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.
success = 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 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.
success = 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.
success = curl.AddOutput("getSite","id","site_id")

'  The next step is to find the Documents document library.
'  
'  Microsoft Graph refers to document libraries as "drives".
success = 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.
success = curl.AddOutput2("getDrives","value","name","Documents",1,"id","document_library_id")

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

'  Search the returned files for an item named "hamlet.json"
'  and save its Microsoft Graph item ID in the file_id variable.
success = curl.AddOutput2("getFiles","value","name","hamlet.json",1,"id","file_id")

'  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.
curlCommand = "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.
success = curl.DoYourThing(curlCommand)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( curl.LastErrorText) & "</pre>"
    Response.End
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.
statusCode = curl.StatusCode
If (statusCode <> 200) Then
    Response.Write "<pre>" & Server.HTMLEncode( curl.ResponseBodyStr) & "</pre>"
    Response.Write "<pre>" & Server.HTMLEncode( "status code = " & statusCode) & "</pre>"
    Response.End
End If

'  The response body contains the contents of the downloaded file.
set sbFileContents = Server.CreateObject("Chilkat.StringBuilder")
success = curl.GetResponseSb(sbFileContents)

'  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.
success = sbFileContents.WriteFile("c:/temp/hamlet.json","utf-8",0)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( sbFileContents.LastErrorText) & "</pre>"
    Response.End
End If

Response.Write "<pre>" & Server.HTMLEncode( "Success.") & "</pre>"

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