MQL5 Trade Requests, Server Responses, and Transaction Logging
Summary
This programming guide explains how MQL5 represents trading operations through request, check, result, and transaction structures. It describes the request fields used for market and pending orders, position changes, and order removal, along with OrderCheck and OrderSend. A key operational distinction is that a successful preliminary check or a successful OrderSend call does not itself guarantee execution; the server response and subsequent transaction events must be inspected.
The article walks through helper functions for opening and closing positions, placing or deleting pending orders, and recording fields from OnTradeTransaction. It presents an expert advisor that logs request details, server return codes, deal and order identifiers, prices, volumes, and transaction types. This is useful for understanding execution plumbing and diagnosing outcomes, but it is an implementation reference rather than a trading strategy or performance study; broker rules and symbol-specific requirements still affect whether requests are accepted or filled.
Key ideas
- MqlTradeRequest fields must be populated according to the requested operation type.
- OrderCheck can identify invalid parameters or insufficient funds, but does not ensure eventual execution.
- OrderSend acceptance means the server processed the request, so its result and later transaction events need review.
- OnTradeTransaction links server events to request and result details for relevant request transactions.
- Logging transaction fields helps diagnose order placement, modification, cancellation, and execution.
Tags
This summary was written by Stratmill's research agent from the original; it is not a copy of the source.