Tcl

curl with Variable Substitution in the Request Body

See more CURL Examples

This example demonstrates using variables located in the request body with the {{variable_name}} syntax. Tcl

load ./chilkat.dll

set success 0

# Variables can also be used within the HTTP request body.
# Variable names are enclosed between {{ and }}

# Here is a curl command with two variables {{name}} and {{age}} located in the data.

# curl -X POST https://api.example.com/data \
#   -H "Content-Type: application/json" \
#   -d '{"name":"{{name}}","age":{{age}}}'

set sbCurl [new_CkStringBuilder]

CkStringBuilder_AppendLn $sbCurl "curl -X POST https://api.example.com/data \\"
CkStringBuilder_AppendLn $sbCurl "  -H \"Content-Type: application/json\" \\"
CkStringBuilder_AppendLn $sbCurl "  -d '{\"name\":\"{{name}}\",\"age\":{{age}}}'"

set curl [new_CkHttpCurl]

# Provide values for variables.
CkHttpCurl_SetVar $curl "name" "Alice"
CkHttpCurl_SetVar $curl "age" "30"

# 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.
set sbRawRequest [new_CkStringBuilder]

set success [CkHttpCurl_ToRawRequest $curl [CkStringBuilder_getAsString $sbCurl] $sbRawRequest]
if {$success == 0} then {
    puts [CkHttpCurl_lastErrorText $curl]
    delete_CkStringBuilder $sbCurl
    delete_CkHttpCurl $curl
    delete_CkStringBuilder $sbRawRequest
    exit
}

puts [CkStringBuilder_getAsString $sbRawRequest]

# Output:

# POST /data HTTP/1.1
# Host: api.example.com
# Content-Type: application/json
# Content-Length: 25
# 
# {"name":"Alice","age":30}

# --------------------------------------------------------------------------------------------------
# Note: Variable substitution in the request body can be turned off by 
# setting the EnableBodyVars property equal to 0

CkHttpCurl_put_EnableBodyVars $curl 0

set success [CkHttpCurl_ToRawRequest $curl [CkStringBuilder_getAsString $sbCurl] $sbRawRequest]
if {$success == 0} then {
    puts [CkHttpCurl_lastErrorText $curl]
    delete_CkStringBuilder $sbCurl
    delete_CkHttpCurl $curl
    delete_CkStringBuilder $sbRawRequest
    exit
}

puts [CkStringBuilder_getAsString $sbRawRequest]

# The raw request with body variable substitution disable:

# Host: api.example.com
# Content-Type: application/json
# Content-Length: 33
# 
# {"name":"{{name}}","age":{{age}}}

delete_CkStringBuilder $sbCurl
delete_CkHttpCurl $curl
delete_CkStringBuilder $sbRawRequest