(Lianja) 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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llSuccess = .F.

llSuccess = .F.

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

loCurl = createobject("CkHttpCurl")

// Provide values for variables
loCurl.SetVar("name","José O'Connor")
loCurl.SetVar("city","München")
loCurl.SetVar("note",'He said "Hello, world!" — and left…')
loCurl.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.
loSbRawRequest = createobject("CkStringBuilder")
llSuccess = loCurl.ToRawRequest(loSbCurl.GetAsString(),loSbRawRequest)
if (llSuccess = .F.) then
    ? loCurl.LastErrorText
    release loSbCurl
    release loCurl
    release loSbRawRequest
    return
endif

? loSbRawRequest.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
//   }
// }


release loSbCurl
release loCurl
release loSbRawRequest