CkPython 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. CkPython

import sys
import chilkat

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}}}'

sbCurl = chilkat.CkStringBuilder()
sbCurl.AppendLn("curl -X POST https://api.example.com/messages \\")
sbCurl.AppendLn("  -H \"Content-Type: application/json\" \\")
sbCurl.AppendLn("  -d '{\"text\":\"{{message}}\"}'")

curl = chilkat.CkHttpCurl()

#  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.
sbRawRequest = chilkat.CkStringBuilder()
success = curl.ToRawRequest(sbCurl.getAsString(),sbRawRequest)
if (success == False):
    print(curl.lastErrorText())
    sys.exit()

print(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!\""}