feat: scalar coercion via resolver map override (Approach 1 — Global)

node/resolvers/index.ts

@@ -1,4 +1,5 @@
 import { mutations as authMutations, queries as authQueries } from './auth'
+import { CoercibleFloat, CoercibleInt, CoercibleString } from '../scalars'
 import {
   fieldResolvers as benefitsFieldResolvers,
   queries as benefitsQueries,
@@ -39,6 +40,9 @@ import {
 } from './session'
 
 export const resolvers = {
+  Int: CoercibleInt,
+  Float: CoercibleFloat,
+  String: CoercibleString,
   ...catalogFieldResolvers,
   ...benefitsFieldResolvers,
   ...profileFieldResolvers,

node/scalars/index.ts

@@ -0,0 +1,86 @@
+import {
+  GraphQLFloat,
+  GraphQLInt,
+  GraphQLScalarType,
+  GraphQLString,
+} from 'graphql'
+import { Kind } from 'graphql/language'
+
+// Replaces GraphQLInt in schema._typeMap so all Int fields accept "20" as 20.
+// parseValue handles variables ({ qty: "20" }), parseLiteral handles inline values.
+export const CoercibleInt = new GraphQLScalarType({
+  name: 'Int',
+  description: GraphQLInt.description,
+  serialize: GraphQLInt.serialize,
+  parseValue: (value) => {
+    const parsed = parseInt(String(value), 10)
+
+    if (isNaN(parsed)) {
+      throw new Error(`Int cannot represent non-integer value: ${value}`)
+    }
+
+    return parsed
+  },
+  parseLiteral: (ast) => {
+    if (ast.kind === Kind.INT) {
+      return parseInt(ast.value, 10)
+    }
+
+    if (ast.kind === Kind.STRING) {
+      const parsed = parseInt(ast.value, 10)
+
+      if (!isNaN(parsed)) return parsed
+    }
+
+    return null
+  },
+})
+
+// Replaces GraphQLFloat in schema._typeMap so all Float fields accept "3.14" as 3.14.
+export const CoercibleFloat = new GraphQLScalarType({
+  name: 'Float',
+  description: GraphQLFloat.description,
+  serialize: GraphQLFloat.serialize,
+  parseValue: (value) => {
+    const parsed = parseFloat(String(value))
+
+    if (isNaN(parsed)) {
+      throw new Error(`Float cannot represent non-numeric value: ${value}`)
+    }
+
+    return parsed
+  },
+  parseLiteral: (ast) => {
+    if (ast.kind === Kind.FLOAT || ast.kind === Kind.INT) {
+      return parseFloat(ast.value)
+    }
+
+    if (ast.kind === Kind.STRING) {
+      const parsed = parseFloat(ast.value)
+
+      if (!isNaN(parsed)) return parsed
+    }
+
+    return null
+  },
+})
+
+// Replaces GraphQLString in schema._typeMap so all String fields accept numbers as strings.
+export const CoercibleString = new GraphQLScalarType({
+  name: 'String',
+  description: GraphQLString.description,
+  serialize: GraphQLString.serialize,
+  parseValue: (value) => String(value),
+  parseLiteral: (ast) => {
+    if (
+      ast.kind === Kind.STRING ||
+      ast.kind === Kind.INT ||
+      ast.kind === Kind.FLOAT ||
+      ast.kind === Kind.BOOLEAN
+    ) {
+      return String(ast.value)
+    }
+
+    return null
+  },
+})