Models validator

Models Validator for Objects. For example, for JSON-parsed Objects that received from network.

---

Docs for models:

All model fields describes as:
from: fieldType

fieldType can be declared as:

• Simple type: String, Number, Date, Object, Array,...

  Array in this case can contain any elements of any types

• Enum: new Set(["some_val", 456, "val2"]) (Field can only be "some_val" or 456 or "val2")
• Specialized Array (fixed length): [Number, String, String] (specialized type of every element in array)
• Specialized Array (unlimited length):

  {
    type: Array,
    item: /**{{fieldType}}**/,
  }

• Long type declaration (you can set optional param):

  {
    type: /**{{fieldType}}**/,
    optional: true, // |=>  field will not be exists in result object if it's not provided
    default: "SomeDefaultValue", // => If field not provided in source data, it will have this value
    from: "some_name", // |=>  field will be searched in the source model as a field with the name "some_name" 
  }

• Nested object declaration:

  {
    type: Object,
    fields: {
      // from: fieldType,
      // ...    
    }
  }

Fields options at long declaration as a result:

• type {{fieldType}} - Describes the type to which the original field value is converted.
• optional [Boolean] - If it has value "false", field can be not provided.
• default [Any value that converts to {{fieldType}}] - If field is optional and it's not provided in source data, it will have this value.
• from [String] - Name of field with which it will be searched in the source model
• item {{long or short fieldType}} - If field type is Array, it can be long or short declaring of field type.
• fields {Object} - If field type is Object, it must be Object with long or short declaring of each object field.

---

Example model description:

const exampleModel = {
  field1: String, // |=> "some_string"
  field2: Number, // |=> 123.4123
  field3: Object, // |=> {any_fields: any_values, ...}
  field4: Array,  // |=> [any_types, ...]
  field5: [Number, String], // |=> [123.1244, "some_string"]
  field6: new Set(["some_val", 456, "val2"]), // |=> Enumeration. Can only be "some_val" or 456 or "val2"
  field7: {
    type: String
  }, // Equals as `field7: String`
  field8: {
    type: Object,
    fields: {
      // ... Any fields of nested model, for example:
      field8_1: String,
    },
  },
  field9: {
    type: Number,
    optional: true, // |=>  field will not be exists in result object if it's not provided
  },
  field10: {
    type: Array,
    item: String, // |=> short or long declaration of each field in array
    from: "some_field_10", // |=> field will searched as field "some_field_10" and written in "field10"
  },
  field11: {
    type: Array,
    item: {  // example of long declaration of each field in array:
      type: Object,
      fields: {
        field11_1: String,
      }
    },
  },
}

---

Example model validation:

const UserModel = { // declare model
  age: Number,
  userName: {
    type: [String, String], // maybe ["name", "surname"]
    from: "user_name", // name in API model
  }, 
  sex: new Set(['male', 'female']), // one of two values
  children: {
    type: Array, // array with unlimited length
    optional: true, // mey be not exists
    item: {
      type: Object,
      fields: {
        name: String,
        age: Number,
      }
    }
  }
}

const response = fetch('/user', {method: 'GET'}); // get unvalidated JSON data
const data = validateModel(UserModel, await response.text()); // validate

For more examples you can see file with tests validateModel.test.js