(PowerShell) curl with Variable Substitution in a GraphQL Request Body

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

Note: This example requires Chilkat v11.5.0 or greater.

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

$success = $false

$success = $false

# Variable names are enclosed between {{ and }}
# Important: Variables should be placed inside the quotes.

# curl -X POST https://api.example.com/graphql \
#   -H "Content-Type: application/graphql; charset=utf-8" \
#   -H "Accept: application/json" \
#   --data-binary "mutation {
#   createUser(
#     input: {
#       name: \"{{name}}\"
#       city: \"{{city}}\"
#       note: \"{{note}}\"
#       bio: \"{{bio}}\"
#     }
#   ) {
#     id
#     name
#   }
# }"

# Build the above curl command.
$sbCurl = New-Object Chilkat.StringBuilder
$sbCurl.AppendLn("curl -X POST https://api.example.com/graphql \`")
$sbCurl.AppendLn("  -H `"Content-Type: application/graphql; charset=utf-8`" \`")
$sbCurl.AppendLn("  -H `"Accept: application/json`" \`")
$sbCurl.AppendLn("  -d `"mutation {")
$sbCurl.AppendLn("  createUser(")
$sbCurl.AppendLn("    input: {")
$sbCurl.AppendLn("      name: \\`"{{name}}\\`"")
$sbCurl.AppendLn("      city: \\`"{{city}}\\`"")
$sbCurl.AppendLn("      note: \\`"{{note}}\\`"")
$sbCurl.AppendLn("      bio: \\`"{{bio}}\\`"")
$sbCurl.AppendLn("    }")
$sbCurl.AppendLn("  ) {")
$sbCurl.AppendLn("    id")
$sbCurl.AppendLn("    name")
$sbCurl.AppendLn("  }")
$sbCurl.AppendLn("}`"")

$curl = New-Object Chilkat.HttpCurl

# Provide values for variables
$curl.SetVar("name","José O'Connor")
$curl.SetVar("city","München")
$curl.SetVar("note","He said `"Hello, world!`" — and left…")
$curl.SetVar("bio","Loves sushi, café visits, and π ≈ 3.14159")

# 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 the quote chars around "Hello, world!" are properly escaped.

# POST /graphql HTTP/1.1
# Accept: application/json
# Host: api.example.com
# Content-Type: application/graphql; charset=utf-8
# Content-Length: 250
# 
# mutation {
#   createUser(
#     input: {
#       name: "José O'Connor"
#       city: "München"
#       note: "He said \"Hello, world!\" — and left…"
#       bio: "Loves sushi, café visits, and π ≈ 3.14159"
#     }
#   ) {
#     id
#     name
#   }
# }