(Go) 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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    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 := chilkat.NewStringBuilder()
    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.NewHttpCurl()

    // 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.NewStringBuilder()
    success = curl.ToRawRequest(*sbCurl.GetAsString(),sbRawRequest)
    if success == false {
        fmt.Println(curl.LastErrorText())
        sbCurl.DisposeStringBuilder()
        curl.DisposeHttpCurl()
        sbRawRequest.DisposeStringBuilder()
        return
    }

    fmt.Println(*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
    //   }
    // }

    sbCurl.DisposeStringBuilder()
    curl.DisposeHttpCurl()
    sbRawRequest.DisposeStringBuilder()