(Xojo Plugin) 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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Dim success As Boolean
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.
Dim sbCurl As New Chilkat.StringBuilder
success = sbCurl.AppendLn("curl -X POST https://api.example.com/graphql \")
success = sbCurl.AppendLn("  -H ""Content-Type: application/graphql; charset=utf-8"" \")
success = sbCurl.AppendLn("  -H ""Accept: application/json"" \")
success = sbCurl.AppendLn("  -d ""mutation {")
success = sbCurl.AppendLn("  createUser(")
success = sbCurl.AppendLn("    input: {")
success = sbCurl.AppendLn("      name: \""{{name}}\""")
success = sbCurl.AppendLn("      city: \""{{city}}\""")
success = sbCurl.AppendLn("      note: \""{{note}}\""")
success = sbCurl.AppendLn("      bio: \""{{bio}}\""")
success = sbCurl.AppendLn("    }")
success = sbCurl.AppendLn("  ) {")
success = sbCurl.AppendLn("    id")
success = sbCurl.AppendLn("    name")
success = sbCurl.AppendLn("  }")
success = sbCurl.AppendLn("}""")

Dim curl As New 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.
Dim sbRawRequest As New Chilkat.StringBuilder
success = curl.ToRawRequest(sbCurl.GetAsString(),sbRawRequest)
If (success = False) Then
    System.DebugLog(curl.LastErrorText)
    Return
End If

System.DebugLog(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
//   }
// }