Handle BigNumber event params and customize Decimal (#63)

* Handle BigNumber event params in watchers

* Customize decimal according to limits of IEEE-754 decimal128

* Add definition for custom scalar BigDecimal

packages/graph-test-watcher/src/artifacts/Example.json

@@ -14,11 +14,41 @@
           "internalType": "uint8",
           "name": "param2",
           "type": "uint8"
+        },
+        {
+          "indexed": false,
+          "internalType": "uint256",
+          "name": "param3",
+          "type": "uint256"
         }
       ],
       "name": "Test",
       "type": "event"
     },
+    {
+      "inputs": [
+        {
+          "internalType": "uint128",
+          "name": "bidAmount1",
+          "type": "uint128"
+        },
+        {
+          "internalType": "uint128",
+          "name": "bidAmount2",
+          "type": "uint128"
+        }
+      ],
+      "name": "addMethod",
+      "outputs": [
+        {
+          "internalType": "uint256",
+          "name": "",
+          "type": "uint256"
+        }
+      ],
+      "stateMutability": "pure",
+      "type": "function"
+    },
     {
       "inputs": [],
       "name": "emitEvent",
@@ -44,6 +74,42 @@
       ],
       "stateMutability": "view",
       "type": "function"
+    },
+    {
+      "inputs": [
+        {
+          "internalType": "uint128",
+          "name": "bidAmount1",
+          "type": "uint128"
+        },
+        {
+          "internalType": "uint128",
+          "name": "bidAmount2",
+          "type": "uint128"
+        }
+      ],
+      "name": "structMethod",
+      "outputs": [
+        {
+          "components": [
+            {
+              "internalType": "uint128",
+              "name": "bidAmount1",
+              "type": "uint128"
+            },
+            {
+              "internalType": "uint128",
+              "name": "bidAmount2",
+              "type": "uint128"
+            }
+          ],
+          "internalType": "struct Example.Bid",
+          "name": "",
+          "type": "tuple"
+        }
+      ],
+      "stateMutability": "pure",
+      "type": "function"
     }
   ],
   "storageLayout": {

packages/graph-test-watcher/src/entity/Author.ts

@@ -27,6 +27,9 @@ export class Author {
   @Column('integer')
   paramInt!: number
 
+  @Column('bigint', { transformer: bigintTransformer })
+  paramBigInt!: number
+
   @Column('varchar')
   paramBytes!: string
 

packages/graph-test-watcher/src/indexer.ts

@@ -584,10 +584,11 @@ export class Indexer implements IndexerInterface {
     switch (logDescription.name) {
       case TEST_EVENT: {
         eventName = logDescription.name;
-        const { param1, param2 } = logDescription.args;
+        const { param1, param2, param3 } = logDescription.args;
         eventInfo = {
           param1,
-          param2
+          param2,
+          param3: BigInt(param3.toString())
         };
 
         break;

packages/graph-test-watcher/src/resolvers.ts

@@ -5,6 +5,8 @@
 import assert from 'assert';
 import BigInt from 'apollo-type-bigint';
 import debug from 'debug';
+import Decimal from 'decimal.js';
+import { GraphQLScalarType } from 'graphql';
 
 import { ValueResult, BlockHeight } from '@vulcanize/util';
 
@@ -23,6 +25,19 @@ export const createResolvers = async (indexer: Indexer, eventWatcher: EventWatch
   return {
     BigInt: new BigInt('bigInt'),
 
+    BigDecimal: new GraphQLScalarType({
+      name: 'BigDecimal',
+      description: 'BigDecimal custom scalar type',
+      parseValue (value) {
+        // value from the client
+        return new Decimal(value);
+      },
+      serialize (value: Decimal) {
+        // value sent to the client
+        return value.toFixed();
+      }
+    }),
+
     Event: {
       __resolveType: (obj: any) => {
         assert(obj.__typename);

packages/graph-test-watcher/src/schema.gql

@@ -62,6 +62,7 @@ union Event = TestEvent
 type TestEvent {
   param1: String!
   param2: Int!
+  param3: BigInt!
 }
 
 type ResultIPLDBlock {
@@ -110,6 +111,7 @@ type Author {
   name: String!
   rating: BigDecimal!
   paramInt: Int!
+  paramBigInt: BigInt!
   paramBytes: Bytes!
   blogs: [Blog!]!
 }