PowerShell 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. PowerShell

Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

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

$curl = New-Object 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.
$sbRawRequest = New-Object Chilkat.StringBuilder
$success = $curl.ToRawRequest($sbCurl.GetAsString(),$sbRawRequest)
if ($success -eq $false) {
    $($curl.LastErrorText)
    exit
}

$($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!\""}