curl-request-tracker

name	curl-request-tracker
description	Pattern for adding request tracking and curl command generation to HTTP client wrapper classes
source	auto-skill
extracted_at	2026-07-09T04:55:02.535Z

Adding Request Tracking & Curl Generation to HTTP Client Wrappers

When to Apply

When an HTTP client wrapper class needs debugging/diagnostic capability to reproduce the last request as a curl command.

Procedure

1. Add Tracking Fields

Add private fields to capture the last request's method and body:

private String _LastMethod;
private String _LastBody;

The URL is typically already tracked (e.g., _LastUrl).

2. Add a Recording Helper

private void recordLastRequest(String method, String body) {
    this._LastMethod = method;
    this._LastBody = body;
}

3. Insert Recording Calls at Every Request Entry Point

Call recordLastRequest(method, body) at the top of each public HTTP method (doGet, doPost, doPut, doDelete, doPatch, downloadData, doUpload, etc.), before any network I/O. This ensures tracking even if the request fails.

• For String body overloads: pass the body directly
• For Map<String, String> form param overloads: encode to key=value&... format first
• For byte[] overloads: record as "<binary N bytes>"
• For multipart upload overloads: record as "<multipart upload>"

4. Implement createLastCurl()

Build the curl command with \\\n (backslash + newline + 2 spaces) for line continuation:

curl -X METHOD \
  'URL' \
  -H 'User-Agent: ...' \
  -H 'Header: value' \
  -H 'Cookie: ...' \
  --proxy 'scheme://host:port' \
  -d 'body'

Key details:

• Wrap URL, header values, cookie, and body in single quotes
• Escape single quotes in values: ' → '\''
• Include User-Agent only if set
• Include proxy only if configured
• Include -d only if body is non-null and non-empty
• Return null if no request has been made yet

5. Shell Escape Helper

private static String escapeShell(String value) {
    if (value == null) return "";
    return value.replace("'", "'\\''");
}

6. Form Data Encoder (if not already present)

private String encodeFormData(Map<String, String> vals) {
    if (vals == null || vals.isEmpty()) return null;
    StringBuilder sb = new StringBuilder();
    String charset = this._Encode == null ? "UTF-8" : this._Encode;
    for (Map.Entry<String, String> entry : vals.entrySet()) {
        if (sb.length() > 0) sb.append("&");
        sb.append(URLEncoder.encode(entry.getKey(), charset))
          .append("=")
          .append(URLEncoder.encode(entry.getValue(), charset));
    }
    return sb.toString();
}

Testing Approach

• Test with a local HttpServer (from com.sun.net.httpserver.HttpServer) to avoid real network calls
• Verify each HTTP method produces correct -X METHOD
• Verify body content appears in -d flag
• Verify headers, cookies, proxy appear as -H / --proxy
• Test shell escaping with values containing single quotes
• Test null/empty cases return null
• Test line break format (\\\n)

Cross-Branch Application

When applying to multiple branches (e.g., main vs jdk17 with different HTTP backends):

• The tracking fields and createLastCurl() method are identical across branches
• Only the insertion points differ (different internal HTTP client APIs)
• Use git stash workflow: stash main changes → checkout target branch → apply same pattern → stash → checkout main → pop