Refactor JSON parsing in HttpClient

5 files changed, 111 insertions, 53 deletions

diff --git a/packages/connect/src/http_client.ts b/packages/connect/src/http_client.ts
index da052ba3c..f738c7e07 100644
--- a/packages/connect/src/http_client.ts
+++ b/packages/connect/src/http_client.ts
@@ -18,7 +18,7 @@ import {
     TokenPairsItem,
     TokenPairsRequest,
 } from './types';
-import {typeConverters} from './utils/type_converters';
+import {relayerResponseJsonParsers} from './utils/relayer_response_json_parsers';
 
 /**
  * This class includes all the functionality related to interacting with a set of HTTP endpoints
@@ -48,18 +48,13 @@ export class HttpClient implements Client {
         const requestOpts = {
             params: request,
         };
-        const tokenPairs = await this._requestAsync('/token_pairs', HttpRequestType.Get, requestOpts);
-        assert.doesConformToSchema(
-            'tokenPairs', tokenPairs, schemas.relayerApiTokenPairsResponseSchema);
-        _.each(tokenPairs, (tokenPair: object) => {
-            typeConverters.convertStringsFieldsToBigNumbers(tokenPair, [
-                'tokenA.minAmount',
-                'tokenA.maxAmount',
-                'tokenB.minAmount',
-                'tokenB.maxAmount',
-            ]);
-        });
-        return tokenPairs;
+        const result = await this._requestAsync(
+            '/token_pairs',
+            HttpRequestType.Get,
+            relayerResponseJsonParsers.parseTokenPairsJson,
+            requestOpts,
+        );
+        return result;
     }
     /**
      * Retrieve orders from the API
@@ -73,10 +68,13 @@ export class HttpClient implements Client {
         const requestOpts = {
             params: request,
         };
-        const orders = await this._requestAsync(`/orders`, HttpRequestType.Get, requestOpts);
-        assert.doesConformToSchema('orders', orders, schemas.signedOrdersSchema);
-        _.each(orders, (order: object) => typeConverters.convertOrderStringFieldsToBigNumber(order));
-        return orders;
+        const result = await this._requestAsync(
+            `/orders`,
+            HttpRequestType.Get,
+            relayerResponseJsonParsers.parseOrdersJson,
+            requestOpts,
+        );
+        return result;
     }
     /**
      * Retrieve a specific order from the API
@@ -85,10 +83,12 @@ export class HttpClient implements Client {
      */
     public async getOrderAsync(orderHash: string): Promise<SignedOrder> {
         assert.doesConformToSchema('orderHash', orderHash, schemas.orderHashSchema);
-        const order = await this._requestAsync(`/order/${orderHash}`, HttpRequestType.Get);
-        assert.doesConformToSchema('order', order, schemas.signedOrderSchema);
-        typeConverters.convertOrderStringFieldsToBigNumber(order);
-        return order;
+        const result = await this._requestAsync(
+            `/order/${orderHash}`,
+            HttpRequestType.Get,
+            relayerResponseJsonParsers.parseOrderJson,
+        );
+        return result;
     }
     /**
      * Retrieve an orderbook from the API
@@ -100,10 +100,13 @@ export class HttpClient implements Client {
         const requestOpts = {
             params: request,
         };
-        const orderBook = await this._requestAsync('/orderbook', HttpRequestType.Get, requestOpts);
-        assert.doesConformToSchema('orderBook', orderBook, schemas.relayerApiOrderBookResponseSchema);
-        typeConverters.convertOrderbookStringFieldsToBigNumber(orderBook);
-        return orderBook;
+        const result = await this._requestAsync(
+            '/orderbook',
+            HttpRequestType.Get,
+            relayerResponseJsonParsers.parseOrderbookResponseJson,
+            requestOpts,
+        );
+        return result;
     }
     /**
      * Retrieve fee information from the API
@@ -115,10 +118,13 @@ export class HttpClient implements Client {
         const requestOpts = {
             payload: request,
         };
-        const fees = await this._requestAsync('/fees', HttpRequestType.Post, requestOpts);
-        assert.doesConformToSchema('fees', fees, schemas.relayerApiFeesResponseSchema);
-        typeConverters.convertStringsFieldsToBigNumbers(fees, ['makerFee', 'takerFee']);
-        return fees;
+        const result = await this._requestAsync(
+            '/fees',
+            HttpRequestType.Post,
+            relayerResponseJsonParsers.parseFeesResponseJson,
+            requestOpts,
+        );
+        return result;
     }
     /**
      * Submit a signed order to the API
@@ -129,10 +135,16 @@ export class HttpClient implements Client {
         const requestOpts = {
             payload: signedOrder,
         };
-        await this._requestAsync('/order', HttpRequestType.Post, requestOpts);
+        await this._requestAsync(
+            '/order',
+            HttpRequestType.Post,
+            _.noop,
+            requestOpts,
+        );
     }
-    private async _requestAsync(path: string, requestType: HttpRequestType,
-                                requestOptions?: HttpRequestOptions): Promise<any> {
+    private async _requestAsync<T>(path: string, requestType: HttpRequestType,
+                                   jsonParser: (json: any) => T,
+                                   requestOptions?: HttpRequestOptions): Promise<T> {
         const params = _.get(requestOptions, 'params');
         const payload = _.get(requestOptions, 'payload');
         let query = '';
@@ -154,6 +166,6 @@ export class HttpClient implements Client {
             throw Error(response.statusText);
         }
         const json = await response.json();
-        return json;
+        return jsonParser(json);
     }
 }
diff --git a/packages/connect/src/utils/orderbook_channel_message_parsers.ts b/packages/connect/src/utils/orderbook_channel_message_parser.ts
index d9a84cca2..adc565d29 100644
--- a/packages/connect/src/utils/orderbook_channel_message_parsers.ts
+++ b/packages/connect/src/utils/orderbook_channel_message_parser.ts
@@ -7,10 +7,10 @@ import {
     OrderbookChannelMessageTypes,
 } from '../types';
 
-import {typeConverters} from './type_converters';
+import {relayerResponseJsonParsers} from './relayer_response_json_parsers';
 
-export const orderbookChannelMessageParsers = {
-    parser(utf8Data: string): OrderbookChannelMessage {
+export const orderbookChannelMessageParser = {
+    parse(utf8Data: string): OrderbookChannelMessage {
         const messageObj = JSON.parse(utf8Data);
         const type: string = _.get(messageObj, 'type');
         assert.assert(!_.isUndefined(type), `Message is missing a type parameter: ${utf8Data}`);
@@ -18,15 +18,15 @@ export const orderbookChannelMessageParsers = {
         switch (type) {
             case (OrderbookChannelMessageTypes.Snapshot): {
                 assert.doesConformToSchema('message', messageObj, schemas.relayerApiOrderbookChannelSnapshotSchema);
-                const orderbook = messageObj.payload;
-                typeConverters.convertOrderbookStringFieldsToBigNumber(orderbook);
-                return messageObj;
+                const orderbookJson = messageObj.payload;
+                const orderbook = relayerResponseJsonParsers.parseOrderbookResponseJson(orderbookJson);
+                return _.assign(messageObj, {payload: orderbook});
             }
             case (OrderbookChannelMessageTypes.Update): {
                 assert.doesConformToSchema('message', messageObj, schemas.relayerApiOrderbookChannelUpdateSchema);
-                const order = messageObj.payload;
-                typeConverters.convertOrderStringFieldsToBigNumber(order);
-                return messageObj;
+                const orderJson = messageObj.payload;
+                const order = relayerResponseJsonParsers.parseOrderJson(orderJson);
+                return _.assign(messageObj, {payload: order});
             }
             default: {
                 return {
diff --git a/packages/connect/src/utils/relayer_response_json_parsers.ts b/packages/connect/src/utils/relayer_response_json_parsers.ts
new file mode 100644
index 000000000..02d88f26d
--- /dev/null
+++ b/packages/connect/src/utils/relayer_response_json_parsers.ts
@@ -0,0 +1,42 @@
+import {assert} from '@0xproject/assert';
+import {schemas} from '@0xproject/json-schemas';
+import * as _ from 'lodash';
+
+import {
+    FeesResponse,
+    OrderbookResponse,
+    SignedOrder,
+    TokenPairsItem,
+} from '../types';
+
+import {typeConverters} from './type_converters';
+
+export const relayerResponseJsonParsers = {
+    parseTokenPairsJson(json: any): TokenPairsItem[] {
+        assert.doesConformToSchema('tokenPairs', json, schemas.relayerApiTokenPairsResponseSchema);
+        return json.map((tokenPair: any) => {
+            return typeConverters.convertStringsFieldsToBigNumbers(tokenPair, [
+                'tokenA.minAmount',
+                'tokenA.maxAmount',
+                'tokenB.minAmount',
+                'tokenB.maxAmount',
+            ]);
+        });
+    },
+    parseOrdersJson(json: any): SignedOrder[] {
+        assert.doesConformToSchema('orders', json, schemas.signedOrdersSchema);
+        return json.map((order: object) => typeConverters.convertOrderStringFieldsToBigNumber(order));
+    },
+    parseOrderJson(json: any): SignedOrder {
+        assert.doesConformToSchema('order', json, schemas.signedOrderSchema);
+        return typeConverters.convertOrderStringFieldsToBigNumber(json);
+    },
+    parseOrderbookResponseJson(json: any): OrderbookResponse {
+        assert.doesConformToSchema('orderBook', json, schemas.relayerApiOrderBookResponseSchema);
+        return typeConverters.convertOrderbookStringFieldsToBigNumber(json);
+    },
+    parseFeesResponseJson(json: any): FeesResponse {
+        assert.doesConformToSchema('fees', json, schemas.relayerApiFeesResponseSchema);
+        return typeConverters.convertStringsFieldsToBigNumbers(json, ['makerFee', 'takerFee']);
+    },
+};
diff --git a/packages/connect/src/utils/type_converters.ts b/packages/connect/src/utils/type_converters.ts
index 28810af1a..5ba1b8291 100644
--- a/packages/connect/src/utils/type_converters.ts
+++ b/packages/connect/src/utils/type_converters.ts
@@ -1,15 +1,17 @@
 import {BigNumber} from 'bignumber.js';
 import * as _ from 'lodash';
 
-// TODO: convert all of these to non-mutating, pure functions
 export const typeConverters = {
-    convertOrderbookStringFieldsToBigNumber(orderbook: object): void {
-        _.each(orderbook, (orders: object[]) => {
-            _.each(orders, (order: object) => this.convertOrderStringFieldsToBigNumber(order));
-        });
+    convertOrderbookStringFieldsToBigNumber(orderbook: any): any {
+        const bids = _.get(orderbook, 'bids', []);
+        const asks = _.get(orderbook, 'asks', []);
+        return {
+            bids: bids.map((order: any) => this.convertOrderStringFieldsToBigNumber(order)),
+            asks: asks.map((order: any) => this.convertOrderStringFieldsToBigNumber(order)),
+        };
     },
-    convertOrderStringFieldsToBigNumber(order: object): void {
-        this.convertStringsFieldsToBigNumbers(order, [
+    convertOrderStringFieldsToBigNumber(order: any): any {
+        return this.convertStringsFieldsToBigNumbers(order, [
             'makerTokenAmount',
             'takerTokenAmount',
             'makerFee',
@@ -18,9 +20,11 @@ export const typeConverters = {
             'salt',
         ]);
     },
-    convertStringsFieldsToBigNumbers(obj: object, fields: string[]): void {
+    convertStringsFieldsToBigNumbers(obj: any, fields: string[]): any {
+        const result = _.assign({}, obj);
         _.each(fields, field => {
-            _.update(obj, field, (value: string) => new BigNumber(value));
+            _.update(result, field, (value: string) => new BigNumber(value));
         });
+        return result;
     },
 };
diff --git a/packages/connect/src/ws_orderbook_channel.ts b/packages/connect/src/ws_orderbook_channel.ts
index a669d8094..849fb9a4e 100644
--- a/packages/connect/src/ws_orderbook_channel.ts
+++ b/packages/connect/src/ws_orderbook_channel.ts
@@ -11,7 +11,7 @@ import {
     WebsocketClientEventType,
     WebsocketConnectionEventType,
 } from './types';
-import {orderbookChannelMessageParsers} from './utils/orderbook_channel_message_parsers';
+import {orderbookChannelMessageParser} from './utils/orderbook_channel_message_parser';
 
 /**
  * This class includes all the functionality related to interacting with a websocket endpoint
@@ -97,7 +97,7 @@ export class WebSocketOrderbookChannel implements OrderbookChannel {
         if (!_.isUndefined(message.utf8Data)) {
             try {
                 const utf8Data = message.utf8Data;
-                const parserResult = orderbookChannelMessageParsers.parser(utf8Data);
+                const parserResult = orderbookChannelMessageParser.parse(utf8Data);
                 if (parserResult.requestId === requestId) {
                     switch (parserResult.type) {
                         case (OrderbookChannelMessageTypes.Snapshot): {