DataFlex
DataFlex
curl How Known Variables Reduce Execution Steps
See more CURL Examples
This example demonstrates how previously resolved values can simplify future executions.
When DoYourThing is called for a curl command, it builds an execution plan by resolving any missing inputs. This may require running one or more helper curl commands to produce the needed values.
As each command runs, any defined output variables are stored in the HttpCurl object and remain available for subsequent calls.
If another curl command is executed afterward—and it requires variables that are already known from earlier executions—those inputs do not need to be resolved again. As a result, the dependency chain is shorter, and the execution plan contains fewer steps.
In other words, each call to DoYourThing benefits from the current set of known variables. The more values that have already been resolved, the simpler and more direct the execution plan becomes.
This demonstrates that dependency resolution is dynamic and incremental: only missing inputs trigger additional steps, while previously computed values are reused automatically.
Chilkat DataFlex Downloads
Use ChilkatAx-win32.pkg
Procedure Test
Boolean iSuccess
Handle hoHttpCurl
String sTargetCurl
String sFnName
String sJsonPath
Variant vJsonOAuth2
Handle hoJsonOAuth2
Variant vPlanJson
Handle hoPlanJson
String sTargetCurl2
String sTemp1
Move False To iSuccess
Move False To iSuccess
// -----------------------------------------------------------------------------
// NOTE:
// This example builds on the earlier multi-step dependency example, where the
// execution plan required multiple curl commands (getSite → getDrives → target).
//
// If you have not seen that example, refer to it here: curl Multi-Step Dependency
//
//
// In this example, we demonstrate how previously resolved variables (site_id,
// drive_id, etc.) are reused across multiple calls to DoYourThing, resulting
// in simpler execution plans for subsequent requests.
// -----------------------------------------------------------------------------
Get Create (RefClass(cComChilkatHttpCurl)) To hoHttpCurl
If (Not(IsComObjectCreated(hoHttpCurl))) Begin
Send CreateComObject of hoHttpCurl
End
// The final curl command we want to execute.
// It depends on {{drive_id}}, which may or may not already be known.
Move "curl -X GET https://graph.microsoft.com/v1.0/drives/{{drive_id}}/root/children" To sTargetCurl
// Define helper function to get drives (produces drive_id, requires site_id)
Move "getDrives" To sFnName
Get ComAddFunction Of hoHttpCurl sFnName "curl -X GET https://graph.microsoft.com/v1.0/sites/{{site_id}}/drives" To iSuccess
Move "value[0].id" To sJsonPath
Get ComAddOutput Of hoHttpCurl sFnName sJsonPath "drive_id" To iSuccess
// Define helper function to get site (produces site_id, requires site_name)
Move "getSite" To sFnName
Get ComAddFunction Of hoHttpCurl sFnName "GET https://graph.microsoft.com/v1.0/sites/root:/sites/{{site_name}}" To iSuccess
Move "id" To sJsonPath
Get ComAddOutput Of hoHttpCurl sFnName sJsonPath "site_id" To iSuccess
// Provide the initial known input.
Send ComSetVar To hoHttpCurl "site_name" "test"
// Configure OAuth2 authentication (client credentials with secrets)
Get Create (RefClass(cComChilkatJsonObject)) To hoJsonOAuth2
If (Not(IsComObjectCreated(hoJsonOAuth2))) Begin
Send CreateComObject of hoJsonOAuth2
End
Set ComEnableSecrets Of hoJsonOAuth2 To True
Get ComUpdateString Of hoJsonOAuth2 "oauth2.client_id" "!!sharepoint|oauth2|client_id" To iSuccess
Get ComUpdateString Of hoJsonOAuth2 "oauth2.client_secret" "!!sharepoint|oauth2|client_secret" To iSuccess
Get ComUpdateString Of hoJsonOAuth2 "oauth2.scope" "https://graph.microsoft.com/.default" To iSuccess
Get ComUpdateString Of hoJsonOAuth2 "oauth2.token_endpoint" "!!sharepoint|oauth2|token_endpoint" To iSuccess
Get pvComObject of hoJsonOAuth2 to vJsonOAuth2
Get ComSetAuth Of hoHttpCurl vJsonOAuth2 To iSuccess
// -----------------------------------------------------------------------------
// EXAMINE THE EXECUTION PLAN (BEFORE RUNNING):
// At this point, drive_id and site_id are NOT known.
// We can inspect the plan that will be executed without sending any requests.
// -----------------------------------------------------------------------------
Get Create (RefClass(cComChilkatJsonObject)) To hoPlanJson
If (Not(IsComObjectCreated(hoPlanJson))) Begin
Send CreateComObject of hoPlanJson
End
Set ComEmitCompact Of hoPlanJson To False
Get pvComObject of hoPlanJson to vPlanJson
Get ComExaminePlan Of hoHttpCurl sTargetCurl vPlanJson To iSuccess
Showln "Execution plan before first call:"
Get ComEmit Of hoPlanJson To sTemp1
Showln sTemp1
// Expected output:
//
// {
// "plan": [{
// "function": "getSite",
// "inputs": ["site_name"],
// "outputs": ["site_id"]
// },{
// "function": "getDrives",
// "inputs": ["site_id"],
// "outputs": ["drive_id"]
// },{
// "function": "targetCurl",
// "inputs": ["drive_id"],
// "outputs": []
// }]
// }
// -----------------------------------------------------------------------------
// FIRST CALL:
// At this point, drive_id and site_id are NOT known.
// The execution plan will include all required steps:
//
// 1) getSite → produces site_id
// 2) getDrives → produces drive_id
// 3) targetCurl → uses drive_id
// -----------------------------------------------------------------------------
Get ComDoYourThing Of hoHttpCurl sTargetCurl To iSuccess
If (iSuccess = False) Begin
Get ComLastErrorText Of hoHttpCurl To sTemp1
Showln sTemp1
Procedure_Return
End
Showln "First call completed."
Get ComGetVar Of hoHttpCurl "site_id" To sTemp1
Showln "site_id = " sTemp1
Get ComGetVar Of hoHttpCurl "drive_id" To sTemp1
Showln "drive_id = " sTemp1
// -----------------------------------------------------------------------------
// SECOND CALL (DIFFERENT TARGET):
// Now that site_id is already known, we can run another curl command that
// depends only on site_id. No need to call getSite again.
//
// Execution plan:
//
// 1) targetCurl2 → uses existing site_id
// -----------------------------------------------------------------------------
Move "curl -X GET https://graph.microsoft.com/v1.0/sites/{{site_id}}" To sTargetCurl2
Get pvComObject of hoPlanJson to vPlanJson
Get ComExaminePlan Of hoHttpCurl sTargetCurl2 vPlanJson To iSuccess
Showln ""
Get ComEmit Of hoPlanJson To sTemp1
Showln sTemp1
// Expected output:
//
// {
// "plan": [{
// "function": "targetCurl",
// "inputs": ["site_id"],
// "outputs": []
// }]
// }
Get ComDoYourThing Of hoHttpCurl sTargetCurl To iSuccess
If (iSuccess = False) Begin
Get ComLastErrorText Of hoHttpCurl To sTemp1
Showln sTemp1
Procedure_Return
End
Showln "Second call completed (used existing site_id)."
// -----------------------------------------------------------------------------
// THIRD CALL (ORIGINAL TARGET AGAIN):
// drive_id is already known from the first call.
// Therefore, no helper functions are needed this time.
//
// Execution plan:
//
// 1) targetCurl → uses existing drive_id
// -----------------------------------------------------------------------------
Get pvComObject of hoPlanJson to vPlanJson
Get ComExaminePlan Of hoHttpCurl sTargetCurl vPlanJson To iSuccess
Showln ""
Get ComEmit Of hoPlanJson To sTemp1
Showln sTemp1
// Expected output:
//
// {
// "plan": [{
// "function": "targetCurl",
// "inputs": ["drive_id"],
// "outputs": []
// }]
// }
Get ComDoYourThing Of hoHttpCurl sTargetCurl To iSuccess
If (iSuccess = False) Begin
Get ComLastErrorText Of hoHttpCurl To sTemp1
Showln sTemp1
Procedure_Return
End
Showln "Third call completed."
Showln "No dependency resolution was needed because all inputs were already known."
End_Procedure