Handling Nullable Fields in Effect Schema with React Hook Form

Effect Schema + react-hook-form Compatibility Issue Or... I'm lost again

Problem: When using Effect Schema with

optionalWith({ nullable: true })

optionalWith({ nullable: true })

for database fields that can be NULL, the types become incompatible with react-hook-form's resolver.
Current Workaround: Using

as any

as any

type assertions in HealthScreeningForm.tsx (lines 89 and 196) with biome-ignore comments.
I'm using

@effect/sql-drizzle

@effect/sql-drizzle

with PostgreSQL where optional fields are stored as NULL in the database. My schema uses

Schema.optionalWith({ nullable: true })

Schema.optionalWith({ nullable: true })

to handle these nullable fields:

// Schema definition
medicalHistoryDiabetes: Schema.optionalWith(Schema.Boolean, { nullable: true });

// Schema definition
medicalHistoryDiabetes: Schema.optionalWith(Schema.Boolean, { nullable: true });

This creates the correct behavior for database operations (NULL

undefined conversion), but causes type incompatibility with

@hookform/resolvers/effect-ts

@hookform/resolvers/effect-ts

. The resolver sees the Encoded type which includes

null

null

, but react-hook-form expects only

boolean | undefined

boolean | undefined

for optional fields.

What I've Tried:
1. Custom transformation - Created

UndefinedFromNull

UndefinedFromNull

helper that transforms

T | null

T | null

T | undefined

T | undefined

, but wrapping with

Schema.optional()

Schema.optional()

re-introduces the null type in the Encoded side.
2. No optional wrapper - Using just the transformation without

Schema.optional()

Schema.optional()

makes all fields required in the struct (even though they can be undefined).
3. Different transformation approaches - Various attempts at Schema.transform and Schema.propertySignature, but the fundamental issue remains: the form resolver looks at the Encoded type which retains null.

Why These Failed:
- The effectTsResolver uses the Encoded type of the schema, not the decoded Type
- Any approach that keeps

null

null

in the Encoded type breaks react-hook-form
- Removing

Schema.optional

Schema.optional

makes fields required in TypeScript even when undefined
- The type system correctly identifies that

boolean | null | undefined

boolean | null | undefined

is not assignable to

boolean | undefined

boolean | undefined

Question:
Is there a recommended pattern for this use case?

Handling Nullable Fields in Effect Schema with React Hook Form

Effect Schema + react-hook-form Compatibility Issue Or... I'm lost again

Problem: When using Effect Schema with

optionalWith({ nullable: true })

optionalWith({ nullable: true })

for database fields that can be NULL, the types become incompatible with react-hook-form's resolver.
Current Workaround: Using

as any

as any

type assertions in HealthScreeningForm.tsx (lines 89 and 196) with biome-ignore comments.
I'm using

@effect/sql-drizzle

@effect/sql-drizzle

with PostgreSQL where optional fields are stored as NULL in the database. My schema uses

Schema.optionalWith({ nullable: true })

Schema.optionalWith({ nullable: true })

to handle these nullable fields:

// Schema definition
medicalHistoryDiabetes: Schema.optionalWith(Schema.Boolean, { nullable: true });

// Schema definition
medicalHistoryDiabetes: Schema.optionalWith(Schema.Boolean, { nullable: true });

This creates the correct behavior for database operations (NULL

undefined conversion), but causes type incompatibility with

@hookform/resolvers/effect-ts

@hookform/resolvers/effect-ts

. The resolver sees the Encoded type which includes

null

null

, but react-hook-form expects only

boolean | undefined

boolean | undefined

for optional fields.

What I've Tried:
1. Custom transformation - Created

UndefinedFromNull

UndefinedFromNull

helper that transforms

T | null

T | null

T | undefined

T | undefined

, but wrapping with

Schema.optional()

Schema.optional()

re-introduces the null type in the Encoded side.
2. No optional wrapper - Using just the transformation without

Schema.optional()

Schema.optional()

null

null

in the Encoded type breaks react-hook-form
- Removing

Schema.optional

Schema.optional

makes fields required in TypeScript even when undefined
- The type system correctly identifies that

boolean | null | undefined

boolean | null | undefined

is not assignable to

boolean | undefined

boolean | undefined

Question:
Is there a recommended pattern for this use case?

Handling Nullable Fields in Effect Schema with React Hook Form

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