Operation Contracts

For explicit write semantics, the schema instance exposes three synchronous built-in operation methods:

userSchema.create(input);
userSchema.replace(input);
userSchema.patch(input);

They all return the same { validatedObject, errors } shape, but they differ in how omitted fields are treated:

• create(): validates a create payload, enforces required, applies defaultTo, and leaves omitted optional fields omitted.
• replace(): validates a full replacement payload, enforces required, applies defaultTo, and preserves omitted fields.
• patch(): validates only explicitly provided fields and returns only the normalized fields that were touched.

These are built-in named operation contracts, not special cases in the engine. If you need a different contract, define a custom operation and the schema will generate a matching method alias automatically.

Worked operation example

This is easier to understand with one schema and three calls:

const profileSchema = createSchema({
  username: { type: 'string', required: true },
  bio: { type: 'string' },
  role: { type: 'string', defaultTo: 'member' }
})

Calling create():

profileSchema.create({
  username: '  alex  '
})

Result:

{
  validatedObject: {
    username: 'alex',
    role: 'member'
  },
  errors: {}
}

Calling replace() with the same payload:

profileSchema.replace({
  username: '  alex  '
})

Result:

{
  validatedObject: {
    username: 'alex',
    role: 'member'
  },
  errors: {}
}

Calling patch() with the same payload:

profileSchema.patch({
  username: '  alex  '
})

Result:

{
  validatedObject: {
    username: 'alex'
  },
  errors: {}
}

That difference is the whole point of operation contracts:

• create() and replace() walk the schema as a contract for the whole object.
• patch() walks only the fields the caller actually touched.
• Defaults apply on operations that opt into defaults.
• Missing required fields are only errors on operations that opt into required checks.