Xojo Plugin Requires Chilkat v11.5.0+

curl with Variable Substitution in a JSON Request Body

See more CURL Examples

This example shows how to use variables inside a JSON request body using the {{variable_name}} syntax. When the HTTP request’s Content-Type indicates JSON, Chilkat automatically applies proper JSON escaping to each substituted value, ensuring the resulting JSON remains valid. Xojo Plugin

Dim success As Boolean
success = False

//  Variable names are enclosed between {{ and }}
//  Important: The variable {{var_name}} should be placed inside the quotes.

//  This is correct:
//  curl -X POST https://api.example.com/messages \
//    -H "Content-Type: application/json" \
//    -d '{"text":"{{message}}"}'

//  This is incorrect:
//    -d '{"text":{{message}}}'

Dim sbCurl As New Chilkat.StringBuilder
success = sbCurl.AppendLn("curl -X POST https://api.example.com/messages \")
success = sbCurl.AppendLn("  -H ""Content-Type: application/json"" \")
success = sbCurl.AppendLn("  -d '{""text"":""{{message}}""}'")

Dim curl As New Chilkat.HttpCurl

//  In this example, the value we'll provide for the "message" variable
//  will contain chars that require JSON escaping.
curl.SetVar "message","He said ""Hello, world!"""

//  To demonstrate how the variables are replaced, this example does not execute the curl command. 
//  Instead, it generates the raw HTTP request that would be sent if the curl command were run.
Dim sbRawRequest As New Chilkat.StringBuilder
success = curl.ToRawRequest(sbCurl.GetAsString(),sbRawRequest)
If (success = False) Then
    System.DebugLog(curl.LastErrorText)
    Return
End If

System.DebugLog(sbRawRequest.GetAsString())

//  The output is shown below.
//  Notice that the quote chars around "Hello World!" are properly JSON escaped.

//  POST /messages HTTP/1.1
//  Host: api.example.com
//  Content-Type: application/json
//  Content-Length: 36
//  
//  {"text":"He said \"Hello, world!\""}