symbol info double HOW

symbol_info_double — How it works¶

📌 Overview¶

This example demonstrates how to retrieve a numeric property of a trading symbol using the low-level asynchronous method symbol_info_double().

The method is used to read symbol parameters that are represented in MetaTrader as floating-point numbers: swaps, spreads, price step, minimum distances, and other trading characteristics.

Each method call requests one specific numeric property of one symbol.

Method Signature¶

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

Key points:

The method is asynchronous and must be called with await
symbol — trading symbol name (e.g., "GBPUSD")
property specifies which numeric property of the symbol to retrieve
deadline and cancellation_event control execution time
The method returns an object with the numeric property value

🧩 Code Example — Getting Swap Rates for a Symbol¶

async def get_swap_info(account: MT5Account, symbol: str):
    # Get long swap
    long_swap_data = await account.symbol_info_double(
        symbol,
        market_info_pb2.SYMBOL_SWAP_LONG
    )

    # Get short swap
    short_swap_data = await account.symbol_info_double(
        symbol,
        market_info_pb2.SYMBOL_SWAP_SHORT
    )

    print(f"Swap for {symbol}:")
    print(f"  Long: {long_swap_data.value:.2f}")
    print(f"  Short: {short_swap_data.value:.2f}")

    return {
        "long": long_swap_data.value,
        "short": short_swap_data.value
    }

In this example, symbol_info_double() is used to retrieve swap values for long and short positions for one symbol.

🟢 Detailed Explanation¶

1️⃣ Requesting Numeric Symbol Property¶

long_swap_data = await account.symbol_info_double(
    symbol,
    market_info_pb2.SYMBOL_SWAP_LONG
)

At this step, one asynchronous call is executed.

The symbol name is passed to the method
The second argument specifies the type of numeric property
A request to the terminal is executed

The result is a response object containing the property value.

2️⃣ Repeated Call for Another Property¶

short_swap_data = await account.symbol_info_double(
    symbol,
    market_info_pb2.SYMBOL_SWAP_SHORT
)

The method is called again, but with a different property value.

Important:

Each call requests exactly one property
Values are not cached
Each parameter is retrieved with a separate request

3️⃣ Extracting Numeric Value¶

long_swap_data.value
short_swap_data.value

The returned object contains a value field.

This field holds the numeric property value
The value type is float

After extracting .value, you can work with the number as a regular Python value.

4️⃣ Using Retrieved Data¶

return {
    "long": long_swap_data.value,
    "short": short_swap_data.value
}

The retrieved values are combined into a dictionary.

This is done solely for convenience of the calling code — the symbol_info_double() method:

Does not combine properties
Does not interpret values
Does not know how they will be used

Summary¶

In this example, symbol_info_double() is used as a source of numeric trading symbol parameters.

The method is called as many times as properties need to be retrieved, and all processing and data combination logic is performed on the user side.