B4X Requires Chilkat v11.7.0+
Box: Apply, Read, and Update File Metadata

Run the reusable setup once per HttpCurl object, then select names and execute the operation. The setup is repeated here only to make this published example independently runnable. Requires an enterprise metadata template with key projectDocument and string fields customerId and status. An administrator must create the template first. This example creates a new instance; if it already exists, begin with GET/PUT instead. The enterprise scope ID is resolved from the current user profile; enterprise membership and the pre-existing template are required.
See the Box API guide for setup and the complete workflow.
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Dim success As Boolean = False

'  Requires Chilkat 11.7.0 or later and a previously unlocked Chilkat bundle.
'  See Global Unlock Sample.
'  Guide: Box API Guide.

success = False

'  BEGIN ONE-TIME SETUP
'  This block is repeated so each published example can run on its own.
'  In an application, run the setup example once and pass the SAME curl object
'  to operation code below. Do not recreate it for every operation.
'  See Reusable Box HttpCurl Setup.
Dim curl As ChilkatHttpCurl
curl.Initialize("curl")
curl.SetVar("access_token", "BOX_ACCESS_TOKEN")
curl.SetVar("parent_name", "/")
'  Box's fixed root ID is an implementation detail; callers supply names.
curl.SetVar("parent_id", "0")
Dim setupCommand As ChilkatStringBuilder
setupCommand.Initialize
Dim setupReplacements As Int

'  Register findParent; registration sends no request.
setupCommand.SetString("curl -X GET " & Chr(34) & "https://api.box.com/2.0/folders/0/items?limit=1000&fields=id,type,name" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer ACCESS_TOKEN" & Chr(34))
setupReplacements = setupCommand.Replace("ACCESS_TOKEN", curl.GetVar("access_token"))
success = curl.AddFunction("findParent", setupCommand.GetAsString)
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If


'  Register findFolder; registration sends no request.
setupCommand.SetString("curl -X GET " & Chr(34) & "https://api.box.com/2.0/folders/{{parent_id}}/items?limit=1000&fields=id,type,name" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer ACCESS_TOKEN" & Chr(34))
setupReplacements = setupCommand.Replace("ACCESS_TOKEN", curl.GetVar("access_token"))
success = curl.AddFunction("findFolder", setupCommand.GetAsString)
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If


'  Register findFile; registration sends no request.
setupCommand.SetString("curl -X GET " & Chr(34) & "https://api.box.com/2.0/folders/{{folder_id}}/items?limit=1000&fields=id,type,name" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer ACCESS_TOKEN" & Chr(34))
setupReplacements = setupCommand.Replace("ACCESS_TOKEN", curl.GetVar("access_token"))
success = curl.AddFunction("findFile", setupCommand.GetAsString)
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If


'  Register findDestination; registration sends no request.
setupCommand.SetString("curl -X GET " & Chr(34) & "https://api.box.com/2.0/folders/0/items?limit=1000&fields=id,type,name" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer ACCESS_TOKEN" & Chr(34))
setupReplacements = setupCommand.Replace("ACCESS_TOKEN", curl.GetVar("access_token"))
success = curl.AddFunction("findDestination", setupCommand.GetAsString)
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If


'  Register getFileDetails; registration sends no request.
setupCommand.SetString("curl -X GET " & Chr(34) & "https://api.box.com/2.0/files/{{file_id}}?fields=id,sha1,file_version" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer ACCESS_TOKEN" & Chr(34))
setupReplacements = setupCommand.Replace("ACCESS_TOKEN", curl.GetVar("access_token"))
success = curl.AddFunction("getFileDetails", setupCommand.GetAsString)
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If


'  Register getEnterprise; registration sends no request.
setupCommand.SetString("curl -X GET " & Chr(34) & "https://api.box.com/2.0/users/me?fields=enterprise" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer ACCESS_TOKEN" & Chr(34))
setupReplacements = setupCommand.Replace("ACCESS_TOKEN", curl.GetVar("access_token"))
success = curl.AddFunction("getEnterprise", setupCommand.GetAsString)
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If


'  Register output rules once. Chilkat 11.7.0 evaluates {{name}} variables
'  when extracting each output, using the current value at that time.
success = curl.AddOutput2("findParent", "entries", "name", "{{parent_name}}", True, "id", "parent_id")
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If

success = curl.AddOutput2("findFolder", "entries", "name", "{{folder_name}}", True, "id", "folder_id")
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If

success = curl.AddOutput2("findFile", "entries", "name", "{{file_name}}", True, "id", "file_id")
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If

success = curl.AddOutput2("findDestination", "entries", "name", "{{destination_name}}", True, "id", "destination_id")
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If

success = curl.AddOutput("getFileDetails", "file_version.id", "file_version_id")
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If

success = curl.AddOutput("getFileDetails", "sha1", "file_sha1")
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If

success = curl.AddOutput("getEnterprise", "enterprise.id", "enterprise_id")
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If

'  END ONE-TIME SETUP
'  The name lookups below assume each listing fits in one page (1000 items).
'  Parent and destination names select root children; folder_name selects a child
'  of parent_name. "/" selects the root parent. These are not arbitrary paths.

'  BEGIN OPERATION -- keep the configured object when reusing it.
'  Inputs are names. Retain cached IDs when the selected names have not changed.
Dim parentName As String = "/"
Dim folderName As String = "documents"
Dim fileName As String = "invoice.pdf"
If (curl.GetVar("parent_name") <> parentName) Or ((parentName = "/") And (curl.VarDefined("parent_id") = False)) Then
    curl.SetVar("parent_name", parentName)
    curl.ClearVar("parent_id")
    curl.ClearVar("folder_id")
    curl.ClearVar("file_id")
    curl.ClearVar("file_version_id")
    curl.ClearVar("file_sha1")
    If parentName = "/" Then
        curl.SetVar("parent_id", "0")
    End If

End If

If curl.GetVar("folder_name") <> folderName Then
    curl.SetVar("folder_name", folderName)
    curl.ClearVar("folder_id")
    curl.ClearVar("file_id")
    curl.ClearVar("file_version_id")
    curl.ClearVar("file_sha1")
End If

If curl.GetVar("file_name") <> fileName Then
    curl.SetVar("file_name", fileName)
    curl.ClearVar("file_id")
    curl.ClearVar("file_version_id")
    curl.ClearVar("file_sha1")
End If

curl.ClearTargetOutput("*")
Dim authorizedCommand1 As ChilkatStringBuilder
authorizedCommand1.Initialize
authorizedCommand1.SetString("curl -X POST " & Chr(34) & "https://api.box.com/2.0/files/{{file_id}}/metadata/enterprise_{{enterprise_id}}/projectDocument" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer {{access_token}}" & Chr(34) & " -H " & Chr(34) & "Content-Type: application/json" & Chr(34) & " -d '{" & Chr(34) & "customerId" & Chr(34) & ":" & Chr(34) & "CUST-1001" & Chr(34) & "," & Chr(34) & "status" & Chr(34) & ":" & Chr(34) & "received" & Chr(34) & "}'")
Dim headerReplacement1 As Int = authorizedCommand1.Replace("{{access_token}}", curl.GetVar("access_token"))
success = curl.DoYourThing(authorizedCommand1.GetAsString)
If (success <> True) Or (curl.StatusCode <> 201) Then
    Log("Box request failed. HTTP status: " & curl.StatusCode)
    Log("Failure reason: " & curl.FailReason)
    Log(curl.ResponseBodyStr)
    Return
End If

curl.ClearTargetOutput("*")
Dim authorizedCommand2 As ChilkatStringBuilder
authorizedCommand2.Initialize
authorizedCommand2.SetString("curl -X GET " & Chr(34) & "https://api.box.com/2.0/files/{{file_id}}/metadata/enterprise_{{enterprise_id}}/projectDocument" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer {{access_token}}" & Chr(34))
Dim headerReplacement2 As Int = authorizedCommand2.Replace("{{access_token}}", curl.GetVar("access_token"))
success = curl.DoYourThing(authorizedCommand2.GetAsString)
If (success <> True) Or (curl.StatusCode <> 200) Then
    Log("Box request failed. HTTP status: " & curl.StatusCode)
    Log("Failure reason: " & curl.FailReason)
    Log(curl.ResponseBodyStr)
    Return
End If

Log(curl.ResponseBodyStr)
curl.ClearTargetOutput("*")
Dim authorizedCommand3 As ChilkatStringBuilder
authorizedCommand3.Initialize
authorizedCommand3.SetString("curl -X PUT " & Chr(34) & "https://api.box.com/2.0/files/{{file_id}}/metadata/enterprise_{{enterprise_id}}/projectDocument" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer {{access_token}}" & Chr(34) & " -H " & Chr(34) & "Content-Type: application/json-patch+json" & Chr(34) & " -d '[{" & Chr(34) & "op" & Chr(34) & ":" & Chr(34) & "replace" & Chr(34) & "," & Chr(34) & "path" & Chr(34) & ":" & Chr(34) & "/status" & Chr(34) & "," & Chr(34) & "value" & Chr(34) & ":" & Chr(34) & "approved" & Chr(34) & "}]'")
Dim headerReplacement3 As Int = authorizedCommand3.Replace("{{access_token}}", curl.GetVar("access_token"))
success = curl.DoYourThing(authorizedCommand3.GetAsString)
If (success <> True) Or (curl.StatusCode <> 200) Then
    Log("Box request failed. HTTP status: " & curl.StatusCode)
    Log("Failure reason: " & curl.FailReason)
    Log(curl.ResponseBodyStr)
    Return
End If

Log("Updated metadata: " & curl.ResponseBodyStr)