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-node/test/subgraph/example1/abis/Example1.json

@@ -13,6 +13,12 @@
         "internalType": "uint8",
         "name": "param2",
         "type": "uint8"
+      },
+      {
+        "indexed": false,
+        "internalType": "uint256",
+        "name": "param3",
+        "type": "uint256"
       }
     ],
     "name": "Test",

packages/graph-node/test/subgraph/example1/generated/Example1/Example1.ts

@@ -30,6 +30,10 @@ export class Test__Params {
   get param2(): i32 {
     return this._event.parameters[1].value.toI32();
   }
+
+  get param3(): BigInt {
+    return this._event.parameters[2].value.toBigInt();
+  }
 }
 
 export class Example1__structMethodResultValue0Struct extends ethereum.Tuple {

packages/graph-node/test/subgraph/example1/generated/schema.ts

@@ -105,6 +105,7 @@ export class Author extends Entity {
     this.set("name", Value.fromString(""));
     this.set("rating", Value.fromBigDecimal(BigDecimal.zero()));
     this.set("paramInt", Value.fromI32(0));
+    this.set("paramBigInt", Value.fromBigInt(BigInt.zero()));
     this.set("paramBytes", Value.fromBytes(Bytes.empty()));
   }
 
@@ -170,6 +171,15 @@ export class Author extends Entity {
     this.set("paramInt", Value.fromI32(value));
   }
 
+  get paramBigInt(): BigInt {
+    let value = this.get("paramBigInt");
+    return value!.toBigInt();
+  }
+
+  set paramBigInt(value: BigInt) {
+    this.set("paramBigInt", Value.fromBigInt(value));
+  }
+
   get paramBytes(): Bytes {
     let value = this.get("paramBytes");
     return value!.toBytes();

packages/graph-node/test/subgraph/example1/schema.graphql

@@ -18,6 +18,7 @@ type Author @entity {
   name: String! # string
   rating: BigDecimal!
   paramInt: Int! # uint8
+  paramBigInt: BigInt! # uint256
   paramBytes: Bytes!
   blogs: [Blog!]! @derivedFrom(field: "author")
 }

packages/graph-node/test/subgraph/example1/src/mapping.ts

@@ -10,6 +10,7 @@ export function handleTest (event: Test): void {
   log.debug('event.address: {}', [event.address.toHexString()]);
   log.debug('event.params.param1: {}', [event.params.param1]);
   log.debug('event.params.param2: {}', [event.params.param2.toString()]);
+  log.debug('event.params.param3: {}', [event.params.param3.toString()]);
   log.debug('event.block.hash: {}', [event.block.hash.toHexString()]);
   log.debug('event.block.stateRoot: {}', [event.block.stateRoot.toHexString()]);
 
@@ -32,8 +33,9 @@ export function handleTest (event: Test): void {
   // Entity fields can be set based on event parameters
   author.name = event.params.param1;
   author.paramInt = event.params.param2;
+  author.paramBigInt = event.params.param3;
   author.paramBytes = event.address;
-  author.rating = BigDecimal.fromString('4');
+  author.rating = BigDecimal.fromString('3.2132354');
 
   // Entities can be written to the store with `.save()`
   author.save();

packages/graph-node/test/subgraph/example1/subgraph.yaml

@@ -19,7 +19,7 @@ dataSources:
         - name: Example1
           file: ./abis/Example1.json
       eventHandlers:
-        - event: Test(string,uint8)
+        - event: Test(string,uint8,uint256)
           handler: handleTest
       blockHandlers:
         - handler: handleBlock