nautechsystems/nautilus_trader · error · anyhow::Error

Order side not set

Error message

Order side not set

What it means

OrderBuilder::build requires side to be explicitly set before constructing the proto Order; dYdX orders must declare BUY or SELL. The error is thrown when the builder's optional side field is still None.

Source

Thrown at crates/adapters/dydx/src/grpc/order.rs:420

        self
    }

    /// Set order's expiration.
    #[must_use]
    pub fn until(mut self, gtof: OrderGoodUntil) -> Self {
        self.until = Some(gtof);
        self
    }

    /// Build the order.
    ///
    /// # Errors
    ///
    /// Returns an error if the order parameters are invalid.
    pub fn build(self) -> Result<Order, anyhow::Error> {
        let side = self
            .side
            .ok_or_else(|| anyhow::anyhow!("Order side not set"))?;
        let size = self
            .size
            .ok_or_else(|| anyhow::anyhow!("Order size not set"))?;

        // Quantize size
        let quantums = self.market_params.quantize_quantity(size)?;

        // Build order ID
        let order_id = Some(OrderId {
            subaccount_id: Some(SubaccountId {
                owner: self.subaccount_owner.clone(),
                number: self.subaccount_number,
            }),
            client_id: self.client_id,
            order_flags: match self.flags {
                OrderFlags::ShortTerm => 0,
                OrderFlags::LongTerm => 64,
                OrderFlags::Conditional => 32,

View on GitHub (pinned to 18893faf8b)

Solutions

1. Always call .side(...) on the builder before .build()
2. Ensure the side-mapping from your internal order type to OrderSide cannot fall through to unset
3. Add a validation check on the caller side before invoking build

Example fix

// before
let builder = OrderBuilder::new(params).size(size).until(until);
let order = builder.build()?;
// after
let builder = OrderBuilder::new(params)
    .side(side) // must be set before build
    .size(size)
    .until(until);
let order = builder.build()?;

anyhow::ensure!(side.is_some(), "side must be set before build()");

When it happens

Trigger: Calling build() (e.g. via build_conditional_order) without having called the builder's side setter, or a code path that conditionally sets side and skips it.

Common situations: Conditional order construction where side is derived from trigger logic and a branch forgets to set it; refactoring that renamed/moved the side() call; passing an OrderSide that failed to map and defaulted to None.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• Order size not set
• Order expiration (until) not set
• slots lock poisoned
• AX whoami account {} supplied no fee rates
• DEX {} does not have initialize event set.

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/978be47fe3e8e782. Report an issue: GitHub.