(Visual FoxPro) 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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LOCAL lnSuccess
LOCAL loSbCurl
LOCAL loCurl
LOCAL loSbRawRequest

lnSuccess = 0

lnSuccess = 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.
loSbCurl = CreateObject('Chilkat.StringBuilder')
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('Chilkat.HttpCurl')

* 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('Chilkat.StringBuilder')
lnSuccess = loCurl.ToRawRequest(loSbCurl.GetAsString(),loSbRawRequest)
IF (lnSuccess = 0) THEN
    ? loCurl.LastErrorText
    RELEASE loSbCurl
    RELEASE loCurl
    RELEASE loSbRawRequest
    CANCEL
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