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Code migration guide

Pine Script to MQL5: semantics before syntax

To convert Pine Script to MQL5, first specify when each rule runs, which bar it reads, and what an order means. Then rebuild the logic as an MT5 custom indicator or Expert Advisor. A converter can draft the source; compilation alone cannot establish equivalent signals or trades.

Open the MQL5 Coding AgentReview MQL5 AI Coding Agent

Bring source you have permission to use and a behavior contract to the MQL5 AI Coding Agent. Review the draft, compile it and compare its signals and trades in MT5.

Conversion map

What changes between TradingView and MetaTrader 5

The migration is a model translation. Use this map to decide where the source behavior belongs before writing target syntax.

Source and target platform conversion map
ConcernSource modelTarget modelMigration decision
Calculation timingPine indicators run on historical bars and realtime updates. Strategies normally calculate at bar close, but calculation settings can change that behavior.An MT5 indicator uses OnCalculate. An EA receives OnTick events for its chart symbol; a new bar requires an explicit check.For a closed-bar rule, evaluate the completed bar once when a new bar is detected. Define restart behavior so attaching the EA mid-bar does not unintentionally replay an entry.
Series and statePine history references count backward from the bar being evaluated. Realtime rollback restores ordinary state before another update; varip can preserve intrabar state.MQL5 array indexes depend on array direction. Indicator reads also have a requested shift: shift 0 is the current, unfinished bar.Write down timestamps for every input. A Pine current-bar value at its close corresponds to MT5 shift 1 after the next bar opens. Explicitly reproduce any state reset or persistence rule.
Indicator handles and output buffersThe source calculates fast and slow averages and plots their values on the chart.MQL5 iMA returns a handle. CopyBuffer reads values from that handle. Custom indicator plots use buffers bound with SetIndexBuffer.Create and check handles during initialization; release unused handles. Check the number of copied values before reading. After binding output buffers, explicitly choose their indexing direction and handle OnCalculate history resets.
Worked timing example: assumed valuesAssume one-minute bars identified by opening time. At the close of the 10:01 bar, fast/slow averages are 101/100; the 10:00 values were 99/100. The upward cross is true: 99 <= 100 and 101 > 100.At the first tick of the 10:02 bar, 10:01 is shift 1 and 10:00 is shift 2. Copy two values starting at shift 1 into ordinary fixed arrays: index 0 holds 10:00; index 1 holds 10:01.Expect one true signal for 10:01, even if several ticks arrive during 10:02. This is a synthetic acceptance case, not market data or a backtest. Also test equality on the newer bar: 100/100 must not count as an upward cross.
Order request versus executionWith default strategy timing, an order created at a bar close can first fill on the next available tick. The TradingView broker emulator supplies the simulated fill.An MT5 trade request, order, deal and position are different records. OrderSend returning true does not by itself prove that a trade filled.Compare the signal timestamp separately from the fill timestamp. Inspect the trade result retcode and track execution through OnTradeTransaction; reconcile rejection and partial execution before another entry attempt.
Position ownershipPine entry IDs, pyramiding and exit rules form the strategy specification.A netting account permits one position per symbol. A hedging account can hold several positions for the same symbol, including opposite directions.Read ACCOUNT_MARGIN_MODE. Define how the EA identifies its trades and closes or reduces them. Do not assume that a Pine entry ID maps directly to an independent MT5 position.

Code example

Read the existing MA-cross fragments with their timing limits

The Pine indicator below evaluates the current bar; the MQL5 fragment also requests shift 0. In its fixed arrays, index 0 is the older copied value and index 1 is the current value. These fragments illustrate a comparison only. The MQL5 side omits handle creation and copy-result checks, and neither example places orders. For the closed-bar acceptance case above, the target must instead read shifts 1 and 2 and process each signal bar once.

Pine Script source fragment
//@version=6
indicator("MA cross", overlay = true)
fast = ta.sma(close, 10)
slow = ta.sma(close, 20)
longSignal = ta.crossover(fast, slow)
plot(fast)
plot(slow)
MQL5 target fragment
double fast[2], slow[2];
CopyBuffer(fastHandle, 0, 0, 2, fast);
CopyBuffer(slowHandle, 0, 0, 2, slow);
bool longSignal = fast[0] <= slow[0] && fast[1] > slow[1];

Workflow

A four-step migration path

Keep generation, target-platform validation, and behavior comparison as separate stages.

  1. 1

    Write a behavior contract

    List inputs, formulas, lookbacks, state, plots, alerts and order rules from the complete permitted source. Include symbols, timeframes and Pine strategy settings. Resolve hidden libraries or unavailable data before requesting an MQL5 draft.

  2. 2

    Build the target structure

    Ask the MQL5 AI Coding Agent for the chosen indicator or EA. Specify event timing, handles, buffer direction and account mode. Request comments explaining each semantic decision so the generated source can be reviewed against the contract.

  3. 3

    Check values before trades

    Compile in MetaEditor 5, then log bar timestamps, input prices, indicator values and signals. Run the synthetic cross case above, an equality case, an insufficient-history case and an EA restart case. Diagnose the first mismatching bar before enabling orders.

  4. 4

    Reconcile order behavior

    Use MT5 Strategy Tester with recorded symbol, period, data and execution settings. Compare entry intent, requests, fills, position size and exits separately. Check rejected orders, repeat ticks, reversals and partial closes, then inspect demo-account behavior.

Manual decisions

Decisions code replacement cannot make

  • Choose a custom indicator for plots and signals or an Expert Advisor for trade execution. Convert only source code you own or have permission to use.
  • Record the Pine calculation settings, confirmed-bar policy, warm-up period, session and timeframe. Decide which state persists across bars and which resets between updates.
  • Specify sizing, entry ownership, duplicate-entry prevention, pyramiding, reversals and partial exits for the target netting or hedging account.

Limitations

What the draft cannot prove

  • Matching compiler output proves neither signal equivalence nor trading performance. Compare timestamps and intermediate values before comparing aggregate backtest results.
  • Different price feeds, sessions, spreads, commissions, contract sizes and fill assumptions can change results even when the formulas match. Record those assumptions with each comparison.
  • A closed-bar EA design cannot automatically preserve a Pine script that depends on intrabar updates or rollback. Higher-timeframe data and unavailable libraries need their own mapping.
  • Pineify can generate and revise a draft. MetaEditor compilation, MT5 testing and review of the intended account behavior remain separate checks. This guide is technical information, not investment advice or a return guarantee.

Use cases

When this conversion is useful

  • Move a Pine overlay into an MT5 custom indicator with named plots and buffers.
  • Rebuild a TradingView strategy as an MQL5 Expert Advisor with an explicit signal and order log.
  • Translate an owned Pine alert condition into an MT5 signal, then separately decide whether it should place an order.

FAQ

Pine Script to MQL5 questions

Official references

Build the MQL5 draft with its native model in view

Bring the complete source and your artifact, timing, data, and order requirements. Validate the result in MetaTrader 5.

Open the MQL5 Coding AgentProduct details