Fields with Arguments Incorrectly Generated as Primitive Properties

[aezapata]

Fields with Arguments Incorrectly Generated as Primitive Properties

Bug Description

The generator incorrectly treats GraphQL fields that have arguments as primitive properties in the MST model, when they should be handled as computed fields or methods.

Expected Behavior

Fields with arguments should:

1. Not be added to the MST model .props()
2. Not generate getter-style selectors
3. Generate method-style selectors that accept arguments

Actual Behavior

Fields with arguments are:

1. Added to MST model props as stored properties
2. Generate getter-style selectors that ignore the arguments
3. Added to primitiveFields and included in modelPrimitives

Example

GraphQL Schema

type OfferBundleAggregation {
  estimatedMonthlyRevenue: OfferPrice!
  estimatedMonthlyProfit: OfferPrice
  price: OfferPrice!
  hashRate24Hr(unit: HashRateUnit): Float
  hashRateIdeal(unit: HashRateUnit): Float
  powerUsage24Hr(unit: PowerUnit): Float
  powerManufacturer(unit: PowerUnit): Float
}

Current Generated Output (Incorrect)

export const OfferBundleAggregationModelBase = ModelBase
  .named('OfferBundleAggregation')
  .props({
    __typename: types.optional(types.literal("OfferBundleAggregation"), "OfferBundleAggregation"),
    // ❌ These should NOT be properties since they have arguments
    hashRate24Hr: types.union(types.undefined, types.null, types.number),
    hashRateIdeal: types.union(types.undefined, types.null, types.number),
    powerUsage24Hr: types.union(types.undefined, types.null, types.number),
    powerManufacturer: types.union(types.undefined, types.null, types.number),
    // ... other props
  })

export class OfferBundleAggregationModelSelector extends QueryBuilder {
  // ❌ These should NOT be getters since they require arguments
  get hashRate24Hr() { return this.__attr(`hashRate24Hr`) }
  get hashRateIdeal() { return this.__attr(`hashRateIdeal`) }
  get powerUsage24Hr() { return this.__attr(`powerUsage24Hr`) }
  get powerManufacturer() { return this.__attr(`powerManufacturer`) }
  // ... other methods
}

Expected Generated Output

export const OfferBundleAggregationModelBase = ModelBase
  .named('OfferBundleAggregation')
  .props({
    __typename: types.optional(types.literal("OfferBundleAggregation"), "OfferBundleAggregation"),
    // ✅ Only fields without arguments should be properties
    // hashRate24Hr, hashRateIdeal, etc. should NOT be here
  })

export class OfferBundleAggregationModelSelector extends QueryBuilder {
  // ✅ Fields with arguments should be methods
  hashRate24Hr(args: {unit: HashRateUnit}) { return this.__attr(`hashRate24Hr`, args) }
  hashRateIdeal(args: {unit: HashRateUnit}) { return this.__attr(`hashRateIdeal`, args) }
  powerUsage24Hr(args: {unit: PowerUnit}) { return this.__attr(`powerUsage24Hr`, args) }
  powerManufacturer(args: {unit: PowerUnit}) { return this.__attr(`powerManufacturer`, args) }
  // ... other methods
}

Root Cause

In the handleFieldType() function around line 449, when processing SCALAR fields, the code adds ALL scalar fields to primitiveFields regardless of whether they have arguments:

case "SCALAR":
  primitiveFields.push(fieldName)  // ❌ This happens even for fields with args
  // ...

Proposed Fix

The logic should check for arguments before classifying fields:

case "SCALAR":
  if (fieldArgs && fieldArgs.length > 0) {
    // Fields with arguments should be treated as methods, not stored properties
    nonPrimitiveFields.push([fieldName, fieldType.name, fieldArgs])
  } else {
    // Only fields without arguments should be primitives
    primitiveFields.push(fieldName)
  }
  // ... rest of scalar handling

Environment

• mst-gql version: ^0.17.2
• Node version: v18.17.0

Additional Context

This affects any GraphQL schema that uses scalar fields with arguments for computed values, which is a common pattern for fields that need unit conversions, formatting options, or other parameterized transformations.