Merge pull request #117 from Polymarket/fix/market-order-types

[PLAT-42] Fixing market orders args

package.json

@@ -1,7 +1,7 @@
 {
     "name": "@polymarket/clob-client",
     "description": "Typescript client for Polymarket's CLOB",
-    "version": "4.5.4",
+    "version": "4.5.5",
     "contributors": [
         {
             "name": "Jonathan Amenechi",

src/client.ts

@@ -103,6 +103,7 @@ import {
 } from "./endpoints";
 import { OrderBuilder } from "./order-builder/builder";
 import { END_CURSOR, INITIAL_CURSOR } from "./constants";
+import { calculateMarketPrice } from "./order-builder/helpers";
 
 export class ClobClient {
     readonly host: string;
@@ -507,8 +508,11 @@ export class ClobClient {
         const negRisk = options?.negRisk ?? false;
 
         if (!userMarketOrder.price) {
-            const marketPrice = await this.getPrice(tokenID, Side.BUY);
-            userMarketOrder.price = parseFloat(marketPrice);
+            userMarketOrder.price = await this.calculateMarketPrice(
+                tokenID,
+                Side.BUY,
+                userMarketOrder.amount,
+            );
         }
 
         if (!priceValid(userMarketOrder.price, tickSize)) {
@@ -824,6 +828,28 @@ export class ClobClient {
         return this.get(`${this.host}${GET_MARKET_TRADES_EVENTS}${conditionID}`);
     }
 
+    public async calculateMarketPrice(
+        tokenID: string,
+        side: Side,
+        amount: number,
+    ): Promise<number> {
+        const book = await this.getOrderBook(tokenID);
+        if (!book) {
+            throw new Error("no orderbook");
+        }
+        if (side === Side.BUY) {
+            if (!book.asks) {
+                throw new Error("no match");
+            }
+            return calculateMarketPrice(book.asks, amount);
+        } else {
+            if (!book.bids) {
+                throw new Error("no match");
+            }
+            return calculateMarketPrice(book.bids, amount);
+        }
+    }
+
     private canL1Auth(): void {
         if (this.signer === undefined) {
             throw L1_AUTH_UNAVAILABLE_ERROR;

src/order-builder/helpers.ts

@@ -16,6 +16,7 @@ import {
     TickSize,
     RoundConfig,
     CreateOrderOptions,
+    OrderSummary,
 } from "../types";
 import { decimalPlaces, roundDown, roundNormal, roundUp } from "../utilities";
 import {
@@ -268,7 +269,7 @@ export const buildMarketBuyOrderCreationArgs = async (
         feeRateBps,
         nonce,
         signer,
-        expiration: (userMarketOrder.expiration || 0).toString(),
+        expiration: "0",
         signatureType,
     } as OrderData;
 };
@@ -301,3 +302,15 @@ export const createMarketBuyOrder = async (
 
     return buildOrder(eoaSigner, exchangeContract, chainId, orderData);
 };
+
+export const calculateMarketPrice = (positions: OrderSummary[], amountToMatch: number) => {
+    let sum = 0;
+    for (let i = 0; i < positions.length; i++) {
+        const p = positions[i];
+        sum += parseFloat(p.size) * parseFloat(p.price);
+        if (sum >= amountToMatch) {
+            return parseFloat(p.price);
+        }
+    }
+    throw new Error("no match");
+};

src/types.ts

@@ -138,11 +138,6 @@ export interface UserMarketOrder {
      */
     nonce?: number;
 
-    /**
-     * Timestamp after which the order is expired.
-     */
-    expiration?: number;
-
     /**
      * Address of the order taker. The zero address is used to indicate a public order
      */