Chilkat2-Python

curl with Variable Substitution in a JSON Request Body

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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. Chilkat2-Python

import sys
import chilkat2

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 = chilkat2.StringBuilder()
sbCurl.AppendLn("curl -X POST https://api.example.com/messages \\")
sbCurl.AppendLn("  -H \"Content-Type: application/json\" \\")
sbCurl.AppendLn("  -d '{\"text\":\"{{message}}\"}'")

curl = chilkat2.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.
sbRawRequest = chilkat2.StringBuilder()
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!\""}