// an object as output from an array

const fields = [
  {
    type: 'text',
    title: 'Title',
    name: 'title',
    constraints: {
      required: {
        message: '^Title is required',
        allowEmpty: false
      }
    },
  },
  {
    type: 'text',
    title: 'Slug',
    name: 'slug',
    constraints: {
      required: {
        message: '^Slug is required',
        allowEmpty: false
      },
      format: {
        pattern: '[a-z0-9_-]+',
        flags: 'i',
        message: '^Can only be a valid slug'
      }
    },
  },
  // etc.
];

const validationRules = fields.reduce(
  (rules, field) => Object.assign(rules, { [field.name]: field.constraints }),
  {}
);