# Validation

The @potionapps/forms package includes a ValidatorEcto module by default which contains validation rules meant to work with Ecto. The validation rules have the same names as Ecto validation rules, but in camel case.

The useForm hook accepts a fields argument which accepts fields in the form:

export interface Field {
  label?: string,
  name: string,
  options?: any[]
  type?: string,
  validations?: Validation[]
}

Where a Validation is defined as:

export interface Validation {
  name: string,
  params?: {[key: string]: any},
  fn?: ValidationFnCustom
}

export type ValidationFnCustom = (validation: Validation, params: any, data: any) => string[]
export type ValidationFn = (validation: Validation, params: any, data: any) => boolean

Example of a set of fields for use in useForm:

[
  {
    "name": "deletedAt",
    "type": "utc_datetime",
    "validations": []
  },
  {
    "name": "email",
    "type": "string",
    "validations": [
      {
        "name": "email"
      },
      {
        "name": "email"
      }
    ]
  },
  {
    "name": "roles",
    "options": [
      "admin",
      "guest"
    ],
    "type": "checkbox",
    "validations": [
      {
        "name": "roles",
        "params": {
          "values": [
            "admin",
            "guest"
          ]
        }
      }
    ]
  }
]

# Custom Validator

If you'd like to use a validator other than ValidatorEcto, the useForm hook accepts a validator argument that will be used to validate your data.

Your validator must adhere to the validator convention:

export type Validator = (data: object, fields: Field[]) => {[key: string]: string[]}