Syntax

The exchange.Buy() function is used to place a buy order. The Buy() function is a member function of the exchange object exchange. The Buy() function operates on the exchange account bound to the exchange object exchange. The purpose of the member functions (methods) of the exchange object is only related to exchange, which will not be repeated in the rest of this document.


    
    
    
exchange.Buy(price, amount)


    
    
    
exchange.Buy(price, amount, ...args)

Examples

The order number returned by exchange.Buy() can be used to query order information and cancel orders.


    javascript
    
    
function main() {
    var id = exchange.Buy(100, 1);
    Log("id:", id);
}


    python
    
    
def main():
    id = exchange.Buy(100, 1)
    Log("id:", id)


    rust
    
    
fn main() {
    let id = exchange.Buy(100, 1).unwrap();
    Log!("id:", id);
}


    c++
    
    
void main() {
    auto id = exchange.Buy(100, 1);
    Log("id:", id);
}

When placing an order for a cryptocurrency futures contract, you must pay attention to whether the trading direction is set correctly. If the trading direction does not match the trading function, an error will be reported:

```log

direction is sell, invalid order type Buy

direction is buy, invalid order type Sell

direction is closebuy, invalid order type Buy

direction is closesell, invalid order type Sell

```


    javascript
    
    
// The following are incorrect calls
function main() {
    exchange.SetContractType("quarter")

    // Set the short direction
    exchange.SetDirection("sell")
    // Placing a buy order will report an error; shorting can only sell
    var id = exchange.Buy(50, 1)

    // Set the long direction
    exchange.SetDirection("buy")
    // Placing a sell order will report an error; going long can only buy
    var id2 = exchange.Sell(60, 1)

    // Set the close-long direction
    exchange.SetDirection("closebuy")
    // Placing a buy order will report an error; closing long can only sell
    var id3 = exchange.Buy(-1, 1)

    // Set the close-short direction
    exchange.SetDirection("closesell")
    // Placing a sell order will report an error; closing short can only buy
    var id4 = exchange.Sell(-1, 1)
}


    python
    
    
# The following are incorrect calls
def main():
    exchange.SetContractType("quarter")
    exchange.SetDirection("sell")
    id = exchange.Buy(50, 1)
    exchange.SetDirection("buy")
    id2 = exchange.Sell(60, 1)
    exchange.SetDirection("closebuy")
    id3 = exchange.Buy(-1, 1)
    exchange.SetDirection("closesell")
    id4 = exchange.Sell(-1, 1)


    rust
    
    
// The following are incorrect calls
fn main() {
    let _ = exchange.SetContractType("quarter");

    // Set the short direction
    let _ = exchange.SetDirection("sell");
    // Placing a buy order will report an error; shorting can only sell
    let id = exchange.Buy(50, 1);

    // Set the long direction
    let _ = exchange.SetDirection("buy");
    // Placing a sell order will report an error; going long can only buy
    let id2 = exchange.Sell(60, 1);

    // Set the close-long direction
    let _ = exchange.SetDirection("closebuy");
    // Placing a buy order will report an error; closing long can only sell
    let id3 = exchange.Buy(-1, 1);

    // Set the close-short direction
    let _ = exchange.SetDirection("closesell");
    // Placing a sell order will report an error; closing short can only buy
    let id4 = exchange.Sell(-1, 1);
}


    c++
    
    
// The following are incorrect calls
void main() {
    exchange.SetContractType("quarter");
    exchange.SetDirection("sell");
    auto id = exchange.Buy(50, 1);
    exchange.SetDirection("buy");
    auto id2 = exchange.Sell(60, 1);
    exchange.SetDirection("closebuy");
    auto id3 = exchange.Buy(-1, 1);
    exchange.SetDirection("closesell");
    auto id4 = exchange.Sell(-1, 1);
}

Spot market order.


    javascript
    
    
// For example, trading pair: ETH_BTC, market order buy
function main() {
    // Place a market order to buy, buying ETH worth 0.1 BTC (quote currency)
    exchange.Buy(-1, 0.1)
}


    python
    
    
def main():
    exchange.Buy(-1, 0.1)


    rust
    
    
// For example, trading pair: ETH_BTC, market order buy
fn main() {
    // Place a market order to buy, buying ETH worth 0.1 BTC (quote currency)
    let _ = exchange.Buy(-1, 0.1);
}


    c++
    
    
void main() {
    exchange.Buy(-1, 0.1);
}

Returns

Type Description

string / null value

Returns the order Id if the order is placed successfully, and returns a null value if the order fails. The Id attribute of the order Order structure on the FMZ platform consists of the exchange symbol code and the exchange's original order Id, separated by an English comma. For example, the Id attribute format of an order for the OKX exchange spot trading pair ETH_USDT is: ETH-USDT,1547130415509278720. When calling the exchange.Buy() function to place an order, the returned order Id is consistent with the Id attribute of the order Order structure.

Arguments

Name	Type	Required	Description
price	number	Yes	The `price` parameter is used to set the order price.
amount	number	Yes	The `amount` parameter is used to set the order amount.
arg	string / number / bool / object / array / any (any type supported by the platform)	No	Extension parameter used to output accompanying information to this order log. Multiple `arg` parameters can be passed in.