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Article-22608-News-Calendar-SQLite-Persistence-Layer

This repository is an article-derived reference project based on the original MQL5 article. It does not claim to reproduce the full original source code unless files are explicitly attached.

Overview

This project documents the MQL5 article implementation that replaces a compile-time CSV news source with a shared SQLite database layer for a news dashboard Expert Advisor.

The described design persists:

  • economic calendar event history
  • triggered trade event IDs for restart-safe deduplication
  • a shared data store accessible from both live charts and the Strategy Tester

The article also adds a canvas-based download progress bar and a live-mode historical download workflow.

Original Article

  • Article ID: 22608
  • Author: Allan Munene Mutiiria
  • Publication date: 2026.05.26
  • Category: MQL5 Articles / Algorithmic trading / Economic calendar dashboard
  • URL: https://www.mql5.com/en/articles/22608

Repository Purpose

This repository serves as a reference/reconstruction project for the article’s architecture and code excerpts around persistent calendar storage in MQL5.

Its purpose is to capture the database-centered redesign introduced in this article:

  • replacing embedded CSV resources with SQLite
  • storing the database in the common terminal folder
  • sharing one persistent store between live mode and tester mode
  • restoring triggered trade IDs after restart
  • downloading historical calendar data on demand without recompilation

Key Concepts

  • SQLite integration through the MQL5 Database API
  • common-folder database sharing via DATABASE_OPEN_COMMON
  • schema creation for events and triggered tables
  • upsert-based event persistence using INSERT OR REPLACE
  • transaction-based bulk writes for calendar history imports
  • time-window event loading for tester execution
  • trade deduplication persistence using stored triggered event IDs
  • pruning old rows to limit database growth
  • canvas-based progress bar visualization during downloads
  • unified refresh logic across live and tester workflows

Algorithm / Architecture Summary

The article describes a two-table SQLite design:

  1. events table
  • stores calendar value records and display/trading metadata
  • uses value_id as the primary key
  • indexes event_time for fast time-range queries
  1. triggered table
  • stores previously traded event_id values
  • preserves deduplication state across restarts

Runtime flow

  • Initialization

  • open or create the shared database

  • create required schema if missing

  • branch by runtime mode:

  • tester mode: load events for the configured backtest window from SQLite

  • live mode: prune old rows, restore recent triggered IDs, optionally download historical data, then load current live events

  • Live download path

  • query calendar history from the MQL5 calendar API

  • enrich values with event/country metadata

  • convert them into the EA’s NewsEvent structure

  • upsert rows in a single database transaction

  • display progress using a CCanvas overlay

  • Trade deduplication

  • append fired event IDs to an in-memory array

  • persist them into the triggered table

  • reload the last 24 hours of triggered IDs on restart

  • Tick handling

  • use a single refresh path

  • redraw only when the event set changes

  • keep trade checks active on every tick

Mentioned or Attached Files

Explicitly attached files

  • MQL5 News Calendar EA PART 12.mq5 — main Expert Advisor entry point
  • News Core.mqh — shared data definitions, theme/layout data, helper structures
  • News Database.mqh — SQLite lifecycle, schema creation, upsert/load/prune/triggered-state functions, download progress support
  • News Interact.mqh — interaction handling and lifecycle wiring
  • News Logic.mqh — live calendar loading, filtering, trading logic, DB-backed deduplication
  • News Render.mqh — dashboard rendering

Files mentioned in text

  • no additional files were clearly mentioned beyond the attached module set

Statistics

  • Language: MQL5
  • Primary storage model: SQLite database in Common/Files
  • Tables described: 2 (events, triggered)
  • Index described: 1 (idx_events_time)
  • Article code scope: database layer, lifecycle integration, UI progress rendering, tester/live data flow

Tags

MQL5, MetaTrader 5, SQLite, Database API, Economic Calendar, News Trading, Strategy Tester, Persistence, Canvas UI, Expert Advisor

Difficulty

Intermediate to Advanced

Requires familiarity with:

  • MQL5 module organization
  • calendar API usage
  • database statements and transactions
  • canvas rendering
  • EA lifecycle and tester/live mode branching

Limitations

  • The full original repository content is not independently verified here beyond the article text and listed attachments.
  • This README is based on the article narrative and code excerpts; some implementation details may depend on prior parts of the series.
  • If the actual attached source files are not present in the processed repository input, this project should be treated as a reference reconstruction rather than a complete build-ready codebase.
  • Installation, compilation, and execution steps are not provided here because the article excerpt does not fully specify the complete environment and dependency setup.

Reference

Original article: https://www.mql5.com/en/articles/22608