(Perl) 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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use chilkat();

$success = 0;

$success = 0;

# 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 = chilkat::CkStringBuilder->new();
$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 = chilkat::CkHttpCurl->new();

# 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 = chilkat::CkStringBuilder->new();
$success = $curl->ToRawRequest($sbCurl->getAsString(),$sbRawRequest);
if ($success == 0) {
    print $curl->lastErrorText() . "\r\n";
    exit;
}

print $sbRawRequest->getAsString() . "\r\n";

# 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
#   }
# }