Objective-C

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. Objective-C

#import <CkoStringBuilder.h>
#import <CkoHttpCurl.h>

BOOL success = NO;

success = NO;

//  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.
CkoStringBuilder *sbCurl = [[CkoStringBuilder alloc] init];
[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: @"}\""];

CkoHttpCurl *curl = [[CkoHttpCurl alloc] init];

//  Provide values for variables
[curl SetVar: @"name" varValue: @"José O'Connor"];
[curl SetVar: @"city" varValue: @"München"];
[curl SetVar: @"note" varValue: @"He said \"Hello, world!\" — and left…"];
[curl SetVar: @"bio" varValue: @"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.
CkoStringBuilder *sbRawRequest = [[CkoStringBuilder alloc] init];
success = [curl ToRawRequest: [sbCurl GetAsString] sb: sbRawRequest];
if (success == NO) {
    NSLog(@"%@",curl.LastErrorText);
    return;
}

NSLog(@"%@",[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
//    }
//  }