Order Types & Execution

This guide provides the technical specifications for BigONE's order system. It details the exact parameter combinations required for each order type to avoid 400 Bad Request errors.

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1. Parameter Matrix for Spot Trading

In Spot trading (POST /viewer/orders), strict validation is applied.

Order Type	side	price	amount	stop_price	operator	Note
LIMIT	Required	Required	Required	-	-	Standard hanging order.
MARKET	Required	-	Required	-	-	amount = Base Asset Quantity.
STOP_LIMIT	Required	Required	Required	Required	Required	Places LIMIT after trigger.
STOP_MARKET	Required	-	Required	Required	Required	Places MARKET after trigger.

warning

• "-" means the field should NOT be sent. If sent, it may cause an error or be ignored (best practice: do not send).
• MARKET Buy: Currently, BigONE Spot API typically requires amount (Base Asset) for Market Buys. If you want to "Spend 100 USDT", you must estimate the BTC amount yourself or check if quote_quantity is supported for that specific endpoint version.

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2. Parameter Matrix for Contract Trading

Contract trading (POST /orders) uses a slightly different schema.

Order Type	side	price	size	stop_price	reduceOnly	Note
LIMIT	Required	Required	Required	-	Optional	Standard.
MARKET	Required	-	Required	-	Optional	Executed at best price.
STOP_LIMIT	-	Required	-	Required	-	See Conditional Order Section below.

Contract Conditional Orders

In the Contract API, Stop/Trigger orders are often handled via a specific conditional object or distinct parameters depending on the API version.

• Standard Orders: Use LIMIT / MARKET.
• Stop Loss / Take Profit: These are often attached to a Position or sent with type=STOP_MARKET and reduceOnly=true.

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3. Time In Force (Execution Flags)

These flags modify how a LIMIT order is processed. They are ignored for MARKET orders.

POST_ONLY

• Payload: "post_only": true
• Logic:
  • If Order Price < Best Ask (for Buy): Order is Accepted (Maker).
  • If Order Price >= Best Ask (for Buy): Order is Rejected or Cancelled.
• Error Code: 50047 (Liquidity taken too much) or similar cancellation state.

IOC (Immediate or Cancel)

• Payload: "immediate_or_cancel": true
• Logic:
  • Matches available liquidity immediately.
  • Unfilled portion is Cancelled (not added to book).
  • Response: You will receive an Order ID, but its state will likely be FILLED or CANCELLED instantly.

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4. Detailed Behavior Scenarios

Scenario A: The "Fat Finger" Protection

You want to buy BTC. Current Price is $50,000. You accidentally send a LIMIT BUY at $55,000.

1. Standard LIMIT: The system matches you against the best sells ($50,000, $50,001...) up to $55,000.
   • Result: You buy immediately at market price, paying Taker fees.
2. With post_only: true: The system sees your price ($55,000) crosses the best ask ($50,000).
   • Result: Order is Rejected. You are saved from paying Taker fees or buying at a bad spread.

Scenario B: Stop Loss Logic

You hold a Long BTC Position. Current Price $50,000. You want to stop loss at $49,000.

1. STOP_MARKET:
   • stop_price: 49000
   • operator: LTE (Less Than or Equal)
   • Behavior: When Mark Price hits 49,000, a MARKET SELL is triggered.
   • Risk: If price crashes to 48,000 instantly, you sell at 48,000.
2. STOP_LIMIT:
   • stop_price: 49000
   • price: 48900 (Limit Price)
   • Behavior: When Mark Price hits 49,000, a LIMIT SELL at 48,900 is placed.
   • Risk: If price crashes straight to 48,000, your Limit (48,900) might not fill, leaving you holding the bag.

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5. Validation Error Codes

If you mess up the parameters, expect these errors:

• 10007 (Parameter Error):
  • Sending price for a MARKET order (in some strict validators).
  • Missing operator for a Stop order.
  • Sending amount with too many decimal places (violating asset_pair scale).
• 50047 (Liquidity Issue):
  • post_only order would have matched immediately.

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Conclusion

• Spot: Be strict. price and amount are Strings. Check the matrix.
• Contract: Be careful with reduceOnly. Use it for closing positions.
• Algo Trading: Always use post_only if your strategy relies on Maker rebates.