B4X Requires Chilkat v11.5.0+

curl with Variable Substitution in a GraphQL Request Body

See more CURL Examples

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. B4X

Dim success As Boolean = 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 ChilkatStringBuilder
sbCurl.Initialize
sbCurl.AppendLn("curl -X POST https://api.example.com/graphql \")
sbCurl.AppendLn("  -H " & Chr(34) & "Content-Type: application/graphql; charset=utf-8" & Chr(34) & " \")
sbCurl.AppendLn("  -H " & Chr(34) & "Accept: application/json" & Chr(34) & " \")
sbCurl.AppendLn("  -d " & Chr(34) & "mutation {")
sbCurl.AppendLn("  createUser(")
sbCurl.AppendLn("    input: {")
sbCurl.AppendLn("      name: \" & Chr(34) & "{{name}}\" & Chr(34))
sbCurl.AppendLn("      city: \" & Chr(34) & "{{city}}\" & Chr(34))
sbCurl.AppendLn("      note: \" & Chr(34) & "{{note}}\" & Chr(34))
sbCurl.AppendLn("      bio: \" & Chr(34) & "{{bio}}\" & Chr(34))
sbCurl.AppendLn("    }")
sbCurl.AppendLn("  ) {")
sbCurl.AppendLn("    id")
sbCurl.AppendLn("    name")
sbCurl.AppendLn("  }")
sbCurl.AppendLn("}" & Chr(34))

Dim curl As ChilkatHttpCurl
curl.Initialize("curl")

'  Provide values for variables
curl.SetVar("name", "José O'Connor")
curl.SetVar("city", "München")
curl.SetVar("note", "He said " & Chr(34) & "Hello, world!" & Chr(34) & " — 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 ChilkatStringBuilder
sbRawRequest.Initialize
success = curl.ToRawRequest(sbCurl.GetAsString, sbRawRequest)
If success = False Then
    Log(curl.LastErrorText)
    Return
End If


Log(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
'    }
'  }