B4X Requires Chilkat v11.7.0+
Box: Reuse HttpCurl and Invalidate Cached IDs

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. Perform three operations with one configured object: cold file lookup, warm download without lookups, then another download to a different local path after clearing only file state. Functions and output rules are registered only once; their variables are evaluated when used.
See the Box API guide for setup and the complete workflow.
Chilkat B4X Downloads

Download Chilkat for B4X
B4X
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 = "images"
Dim fileName As String = "penguins.jpg"
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.SetVar("local_path", "qa_output/penguins.jpg")
'  Operation 1: get information by name. This resolves folder_id and file_id.
curl.ClearTargetOutput("*")
Dim authorizedCommand1 As ChilkatStringBuilder
authorizedCommand1.Initialize
authorizedCommand1.SetString("curl -X GET " & Chr(34) & "https://api.box.com/2.0/files/{{file_id}}?fields=id,name" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer {{access_token}}" & 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 <> 200) Then
    Log("Box request failed. HTTP status: " & curl.StatusCode)
    Log("Failure reason: " & curl.FailReason)
    Log(curl.ResponseBodyStr)
    Return
End If

'  Operation 2: keep the same object and IDs. Only the final download is needed.
Dim warmPlan As ChilkatJsonObject
warmPlan.Initialize
warmPlan.EmitCompact = False
Dim authorizedCommand2 As ChilkatStringBuilder
authorizedCommand2.Initialize
authorizedCommand2.SetString("curl -X GET " & Chr(34) & "https://api.box.com/2.0/files/{{file_id}}/content" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer {{access_token}}" & Chr(34) & " -L -o " & Chr(34) & "{{local_path}}" & Chr(34))
Dim headerReplacement2 As Int = authorizedCommand2.Replace("{{access_token}}", curl.GetVar("access_token"))
success = curl.ExaminePlan(authorizedCommand2.GetAsString, warmPlan)
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If

Log(warmPlan.Emit)
curl.ClearTargetOutput("*")
Dim authorizedCommand3 As ChilkatStringBuilder
authorizedCommand3.Initialize
authorizedCommand3.SetString("curl -X GET " & Chr(34) & "https://api.box.com/2.0/files/{{file_id}}/content" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer {{access_token}}" & Chr(34) & " -L -o " & Chr(34) & "{{local_path}}" & 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

'  Operation 3: explicitly invalidate file state, retaining the known folder.
'  Here we select the same name so this demonstration needs only one real file.
'  Substitute another filename to switch files in this folder.
'  The existing output rule reads the current file_name; do not register it again.
curl.ClearVar("file_id")
curl.ClearVar("file_version_id")
curl.ClearVar("file_sha1")
curl.SetVar("file_name", "penguins.jpg")
curl.SetVar("local_path", "qa_output/penguins-copy.jpg")
Dim authorizedCommand4 As ChilkatStringBuilder
authorizedCommand4.Initialize
authorizedCommand4.SetString("curl -X GET " & Chr(34) & "https://api.box.com/2.0/files/{{file_id}}/content" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer {{access_token}}" & Chr(34) & " -L -o " & Chr(34) & "{{local_path}}" & Chr(34))
Dim headerReplacement4 As Int = authorizedCommand4.Replace("{{access_token}}", curl.GetVar("access_token"))
success = curl.ExaminePlan(authorizedCommand4.GetAsString, warmPlan)
If success <> True Then
    Log(curl.LastErrorText)
    Return
End If

Log(warmPlan.Emit)
curl.ClearTargetOutput("*")
Dim authorizedCommand5 As ChilkatStringBuilder
authorizedCommand5.Initialize
authorizedCommand5.SetString("curl -X GET " & Chr(34) & "https://api.box.com/2.0/files/{{file_id}}/content" & Chr(34) & " -H " & Chr(34) & "Authorization: Bearer {{access_token}}" & Chr(34) & " -L -o " & Chr(34) & "{{local_path}}" & Chr(34))
Dim headerReplacement5 As Int = authorizedCommand5.Replace("{{access_token}}", curl.GetVar("access_token"))
success = curl.DoYourThing(authorizedCommand5.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

'  Changing parent_name invalidates parent_id, folder_id, and file state.
'  Changing folder_name invalidates folder_id and file state.
'  Changing destination_name invalidates destination_id.