symbol exist HOW

symbol_exist — How it works¶

📌 Overview¶

This example demonstrates how to check whether a trading symbol exists in the terminal using the low-level asynchronous method symbol_exist().

The method is used for basic input data validation: before subscribing, before trading, or before loading symbol parameters.

It answers only one question:

Is a symbol with this name known to the terminal?

Method Signature¶

async def symbol_exist(
    symbol: str,
    deadline: Optional[datetime] = None,
    cancellation_event: Optional[asyncio.Event] = None,
):

Key points:

The method is asynchronous and must be called with await
symbol — symbol name as a string (e.g., "EURUSD")
deadline and cancellation_event control execution time
The method returns an object with information about symbol existence

🧩 Code Example — Checking Multiple Symbols¶

async def check_symbols(account: MT5Account, symbols: list[str]):
    results = {}

    for symbol in symbols:
        data = await account.symbol_exist(symbol=symbol)
        results[symbol] = data.exists

    for symbol, exists in results.items():
        status = "[OK]" if exists else "[ERROR]"
        print(f"{status} {symbol}: {'exists' if exists else 'not found'}")

    return results

In this example, symbol_exist() is used to sequentially check a list of symbols.

🟢 Detailed Explanation¶

1️⃣ Iterating Through Symbol List¶

for symbol in symbols:

The function iterates through a list of strings, where each string is a trading symbol name.

Checks are performed sequentially, for each symbol separately.

2️⃣ Checking Symbol Existence¶

data = await account.symbol_exist(symbol=symbol)

At this step, one asynchronous call is executed.

The symbol name is passed to the method
The terminal checks whether such a symbol is known
The result is returned as a response object

The method does not throw an error if the symbol is not found — this information is returned in the response data.

3️⃣ Extracting Check Result¶

results[symbol] = data.exists

The response object contains the exists field.

True — symbol exists
False — symbol not found

Only this fact is saved to the dictionary, without additional symbol information.

4️⃣ Processing Results¶

for symbol, exists in results.items():

After all checks are completed, results are processed separately.

This allows:

First collecting data
Then making decisions or displaying information

5️⃣ Displaying Information¶

status = "[OK]" if exists else "[ERROR]"
print(f"{status} {symbol}: {'exists' if exists else 'not found'}")

Regular application logic is used here:

A human-readable status is formed
Symbol name and check result are displayed

This code does not affect the check itself — it's only for convenience.

Summary¶

In this example, symbol_exist() is used as a simple way to verify the correctness of symbol names.

The method is called for each symbol separately, returns information about its existence, and all result processing logic remains on the calling code side.