Validation and codecs

Dates and field codecs

schema: {happenedAt: 'date'} and dateFields: ['metadata.receivedAt'] parse stored values into Date. Generated date metadata is automatic. A codec handles arbitrary types:

const invoices = defineModel<Invoice>({
  name: 'Invoice',
  codecs: {
    issuedAt: dateCodec,
    total: {
      toDatabase: (v: Money) => ({ amount: v.amount, currency: v.currency }),
      fromDatabase: (v) => new Money(v),
    },
  },
});

Codecs run on insert, upsert, replacement, matching $set fields, and reads. A field cannot also use a date schema/dateFields transform. Partial projections parse only returned fields; included models use their own codecs.

Validation

validateCreate covers insert/upsert after metadata is added; validateReplace covers replacement. Each can be async and return a transformed document. Patch and raw mutation intentionally skip full-document validation. parse is an output transform, not storage validation.

const validated = defineModel<User>({
  name: 'User', plugins: [withModelValidator(userStandardSchema)],
});

withModelValidator() adapts Standard Schema v1, supports async validation and transformed output, and throws ModelValidationError with structured issues. Generated metadata survives validators that strip unknown keys. Existing validators conflict instead of being replaced. Transaction validation can repeat, so keep it deterministic and side-effect free.