Address PR feedback

3 files changed, 8 insertions, 4 deletions

diff --git a/packages/pipeline/src/utils/constants.ts b/packages/pipeline/src/utils/constants.ts
new file mode 100644
index 000000000..56f3e82d8
--- /dev/null
+++ b/packages/pipeline/src/utils/constants.ts
@@ -0,0 +1,3 @@
+// Block number when the Exchange contract was deployed to mainnet.
+export const EXCHANGE_START_BLOCK = 6271590;
+export const INFURA_ROOT_URL = 'https://mainnet.infura.io';
diff --git a/packages/pipeline/src/utils/index.ts b/packages/pipeline/src/utils/index.ts
index 718ea6133..2096a0a39 100644
--- a/packages/pipeline/src/utils/index.ts
+++ b/packages/pipeline/src/utils/index.ts
@@ -1,5 +1,6 @@
 import { BigNumber } from '@0x/utils';
 export * from './transformers';
+export * from './constants';
 
 /**
  * If the given BigNumber is not null, returns the string representation of that
diff --git a/packages/pipeline/src/utils/transformers/big_number.ts b/packages/pipeline/src/utils/transformers/big_number.ts
index a0471a5e3..5f2e4d565 100644
--- a/packages/pipeline/src/utils/transformers/big_number.ts
+++ b/packages/pipeline/src/utils/transformers/big_number.ts
@@ -3,13 +3,13 @@ import { ValueTransformer } from 'typeorm/decorator/options/ValueTransformer';
 
 export class BigNumberTransformer implements ValueTransformer {
     // tslint:disable-next-line:prefer-function-over-method
-    public to(value: BigNumber): string {
-        return value.toString();
+    public to(value: BigNumber | null): string | null {
+        return value === null ? null : value.toString();
     }
 
     // tslint:disable-next-line:prefer-function-over-method
-    public from(value: string): BigNumber {
-        return new BigNumber(value);
+    public from(value: string | null): BigNumber | null {
+        return value === null ? null : new BigNumber(value);
     }
 }