codegen: Set non-nullable values in constructor with zero/empty values

This is being done so that developers don't have issues with
accessing a non-nullable value and it being `null`, that causes a
runtime error.

Author: evaporei

src/codegen/schema.js

@@ -55,7 +55,7 @@ module.exports = class SchemaCodeGenerator {
     let klass = tsCodegen.klass(name, { export: true, extends: 'Entity' })
 
     // Generate and add a constructor
-    klass.addMethod(this._generateConstructor(name))
+    klass.addMethod(this._generateConstructor(name, def.get('fields')))
 
     // Generate and add save() and getById() methods
     this._generateStoreMethods(name).forEach(method => klass.addMethod(method))
@@ -72,14 +72,39 @@ module.exports = class SchemaCodeGenerator {
     return klass
   }
 
-  _generateConstructor(entityName) {
+  // Fields that are non-nullable get an empty/zero value set in the class constructor.
+  _generateDefaultFieldValues(fields) {
+    const indexOfIdField = fields.findIndex(field => field.getIn(['name', 'value']) === 'id')
+    const fieldsWithoutId = fields.remove(indexOfIdField)
+
+    const fieldsSetCalls = fieldsWithoutId
+      .map(field => {
+        const name = field.getIn(['name', 'value'])
+        const type = this._typeFromGraphQl(field.get('type'))
+        const isNullable = type instanceof tsCodegen.NullableType
+
+        return { name, type, isNullable }
+      })
+      .filter(({ isNullable }) => !isNullable)
+      .map(({ name, type, isNullable }) => {
+        const fieldTypeString = isNullable ? type.inner.toString() : type.toString()
+
+        return `
+        this.set('${name}', ${typesCodegen.initializedValueFromAsc(fieldTypeString)})`
+      })
+
+    return fieldsSetCalls.join('')
+  }
+
+  _generateConstructor(entityName, fields) {
     return tsCodegen.method(
       'constructor',
       [tsCodegen.param('id', tsCodegen.namedType('string'))],
       undefined,
       `
       super()
       this.set('id', Value.fromString(id))
+      ${this._generateDefaultFieldValues(fields)}
       `,
     )
   }

src/codegen/types/conversions.js

@@ -188,27 +188,28 @@ const VALUE_TO_ASSEMBLYSCRIPT = [
 const ASSEMBLYSCRIPT_TO_VALUE = [
   // Arrays
 
-  ['Array<Address>', '[Bytes]', code => `Value.fromBytesArray(${code})`],
-  ['Array<Bytes>', '[Bytes]', code => `Value.fromBytesArray(${code})`],
-  ['Array<boolean>', '[Boolean]', code => `Value.fromBooleanArray(${code})`],
-  ['Array<i32>', '[Int]', code => `Value.fromI32Array(${code})`],
-  ['Array<BigInt>', '[BigInt]', code => `Value.fromBigIntArray(${code})`],
-  ['Array<string>', '[String]', code => `Value.fromStringArray(${code})`],
-  ['Array<string>', '[ID]', code => `Value.fromStringArray(${code})`],
-  ['Array<BigDecimal>', '[BigDecimal]', code => `Value.fromBigDecimalArray(${code})`],
-  ['Array<string>', /\[.*\]/, code => `Value.fromStringArray(${code})`],
+  ['Array<Address>', '[Bytes]', code => `Value.fromBytesArray(${code})`, 'new Array(0)'],
+  ['Array<Bytes>', '[Bytes]', code => `Value.fromBytesArray(${code})`, 'new Array(0)'],
+  ['Array<boolean>', '[Boolean]', code => `Value.fromBooleanArray(${code})`, 'new Array(0)'],
+  ['Array<i32>', '[Int]', code => `Value.fromI32Array(${code})`, 'new Array(0)'],
+  ['Array<BigInt>', '[BigInt]', code => `Value.fromBigIntArray(${code})`, 'new Array(0)'],
+  ['Array<string>', '[String]', code => `Value.fromStringArray(${code})`, 'new Array(0)'],
+  ['Array<string>', '[ID]', code => `Value.fromStringArray(${code})`, 'new Array(0)'],
+  ['Array<BigDecimal>', '[BigDecimal]', code => `Value.fromBigDecimalArray(${code})`, 'new Array(0)'],
+  ['Array<string>', /\[.*\]/, code => `Value.fromStringArray(${code})`, 'new Array(0)'],
+  ['Array<string | null>', null, code => `Value.fromStringArray(${code})`, 'new Array(0)'],
 
   // Scalar values
 
-  ['Address', 'Bytes', code => `Value.fromBytes(${code})`],
-  ['Bytes', 'Bytes', code => `Value.fromBytes(${code})`],
-  ['boolean', 'Boolean', code => `Value.fromBoolean(${code})`],
-  ['i32', 'Int', code => `Value.fromI32(${code})`],
-  ['BigInt', 'BigInt', code => `Value.fromBigInt(${code})`],
-  ['string', 'String', code => `Value.fromString(${code})`],
-  ['string', 'ID', code => `Value.fromString(${code})`],
-  ['BigDecimal', 'BigDecimal', code => `Value.fromBigDecimal(${code})`],
-  ['string', /.*/, code => `Value.fromString(${code})`],
+  ['Address', 'Bytes', code => `Value.fromBytes(${code})`, 'Address.zero()'],
+  ['Bytes', 'Bytes', code => `Value.fromBytes(${code})`, 'Bytes.empty()'],
+  ['boolean', 'Boolean', code => `Value.fromBoolean(${code})`, 'false'],
+  ['i32', 'Int', code => `Value.fromI32(${code})`, '0'],
+  ['BigInt', 'BigInt', code => `Value.fromBigInt(${code})`, 'BigInt.zero()'],
+  ['string', 'String', code => `Value.fromString(${code})`, "''"],
+  ['string', 'ID', code => `Value.fromString(${code})`, "''"],
+  ['BigDecimal', 'BigDecimal', code => `Value.fromBigDecimal(${code})`, 'BigDecimal.zero()'],
+  ['string', /.*/, code => `Value.fromString(${code})`, "''"],
 ]
 
 /**

src/codegen/types/index.js

@@ -66,6 +66,27 @@ const findConversionToType = (fromTypeSystem, toTypeSystem, toType) => {
   return objectifyConversion(fromTypeSystem, toTypeSystem, conversion)
 }
 
+const findInitializationForType = (fromTypeSystem, toTypeSystem, ascType) => {
+  const conversions = conversionsForTypeSystems(fromTypeSystem, toTypeSystem)
+
+  const conversion = conversions.find(conversion =>
+    typeof conversion.get(0) === 'string'
+      ? conversion.get(0) === ascType
+      : ascType.match(conversion.get(0)),
+  )
+
+  if (conversion === undefined) {
+    throw new Error(
+      `Conversion from '${fromTypeSystem}' to '${toTypeSystem}' for ` +
+        `target type '${ascType}' is not supported`,
+    )
+  }
+
+  const conversionObj = objectifyConversion(fromTypeSystem, toTypeSystem, conversion)
+
+  return conversionObj.get('convert')(conversion.get(3))
+}
+
 // High-level type system API
 
 const ascTypeForEthereum = ethereumType =>
@@ -95,6 +116,9 @@ const valueToAsc = (code, valueType) =>
 const valueFromAsc = (code, valueType) =>
   findConversionToType('AssemblyScript', 'Value', valueType).get('convert')(code)
 
+const initializedValueFromAsc = ascType =>
+  findInitializationForType('AssemblyScript', 'Value', ascType)
+
 module.exports = {
   // ethereum <-> AssemblyScript
   ascTypeForEthereum,
@@ -107,4 +131,5 @@ module.exports = {
   valueTypeForAsc,
   valueToAsc,
   valueFromAsc,
+  initializedValueFromAsc,
 }

src/codegen/types/index.test.js

@@ -449,4 +449,26 @@ describe('AssemblyScript -> Value', () => {
     expect(codegen.valueFromAsc('x', '[String]')).toBe('Value.fromStringArray(x)')
     expect(codegen.valueTypeForAsc('Array<string>')).toBe('[String]')
   })
+
+  describe('Initialization for zero/empty values', () => {
+    test('Array<string>', () => {
+      expect(codegen.initializedValueFromAsc('Array<string>')).toBe('Value.fromStringArray(new Array(0))')
+    })
+
+    test('Array<string | null>', () => {
+      expect(codegen.initializedValueFromAsc('Array<string | null>')).toBe('Value.fromStringArray(new Array(0))')
+    })
+
+    test('i32', () => {
+      expect(codegen.initializedValueFromAsc('i32')).toBe('Value.fromI32(0)')
+    })
+
+    test('string', () => {
+      expect(codegen.initializedValueFromAsc('string')).toBe("Value.fromString('')")
+    })
+
+    test('BigInt', () => {
+      expect(codegen.initializedValueFromAsc('BigInt')).toBe('Value.fromBigInt(BigInt.zero())')
+    })
+  })
 })