Helpers

namespace Helpers

Import const { Types: { Helpers } } = require('mythix-orm');

Helpers are a set of utilities used to assist with defaultValue attributes on model fields.

Default values for fields in Mythix ORM are generally used in two different places: As column values directly, or as DEFAULT VALUE for columns when defining tables in the database. When creating tables the defaultValue of a field will generally only ever be used if it has the remote flag set. Otherwise, Mythix ORM simply provides the defaultValue to the database directly during INSERT and UPDATE operations.

const { Model, Types } = require('mythix-orm');

class TestModel extends Model {
  static fields = {
    myCustomDate: {
      type: Types.STRING(32),
      // Inform Mythix ORM that our `defaultValue` should be
      // applied on every `UPDATE` operation... even if the
      // field already has a value.
      defaultValue: Types.Helpers.defaultValueFlags(() => {
        return (new Date()).toISOString();
      }, { onUpdate: true }),
      allowNull: false,
      index: true,
    }
  };
}

function checkDefaultValueFlags(
    func: Function,
    checkFlags: Array<string>,
): boolean 📜

Check if the provided defaultValue method has specific flags set. The flags are provided via their name.

Arguments:

• func: Function

  The defaultValue function to check.

• checkFlags: Array<string>

  The flags to check. Acceptable values are: [ 'onInitialize', 'onInsert', 'onUpdate', 'onStore', 'literal', 'remote' ]

Return value: boolean

Return true if all provided checkFlags are true. If any provided flag results in false, then the method will return false. In short, all provided flags must be true, otherwise false is returned.

See also: Helpers.defaultValueFlags

function defaultValueFlags(
    func: Function,
    flags: object,
): Function 📜

Give a defaultValue method certain flags to assist Mythix ORM in working with a field's defaultValue.

defaultValue flags change the way a defaultValue for a field behaves. For example, if the FLAG_LITERAL is set, then the database will not escape the default value.

By default, all defaultValue attributes on fields (that are methods) have the flags FLAG_ON_INITIALIZE, which simply tells Mythix ORM to call the defaultValue method and assign the result to the field as soon as the model is instantiated. This is the default behavior of all defaultValue attributes... unless the defined flags change that default behavior. As soon as any flag is set on a defaultValue method, the FLAG_ON_INITIALIZE value will be cleared.

This adds an attribute named mythixFlags to the provided method. This attribute is then used by Mythix ORM to know what to do with the defaultValue method provided on a field.

Arguments:

• func: Function

  The defaultValue function to apply flags to.

• flags: object

  An object, specifying which flags to enable or disable. The allowed properties are listed in the table below.

  Option	Type	Default Value	Description
  onInitialize	boolean	true	If true, then assign the defaultValue as soon as a model is instantiated.
  onInsert	boolean	false	If true, then only assign the defaultValue when an INSERT operation is being executed.
  onUpdate	boolean	false	If true, then only assign the defaultValue when an UPDATE operation is being executed.
  onStore	boolean	false	If true, then only assign the defaultValue when an INSERT or UPDATE operation is being executed.
  literal	boolean	false	If true, then inform Mythix ORM that the value is a literal, and not to escape it.
  remote	boolean	false	If true, then inform Mythix ORM that the value is provided by the database itself.

Return value: Function

The method provided, with a new mythixFlags assigned to it.

function getDefaultValueFlags(
    func,
): number 📜

Fetch the mythixFlags attribute on the provided function. If none is found, or no method is provided, then the value 0 will be returned instead.

Arguments:

• func

Return value: number

The defaultValue flags as a bitmask. If none is found, or no method is provided, then 0 will be returned instead.

See also: Helpers.defaultValueFlags

property Helpers::FLAG_LITERAL: number = 0x08

This flag informs Mythix ORM that the defaultValue is intended to be a literal value, and should not be escaped.

property Helpers::FLAG_ON_INITIALIZE: number = 0x01

This flag informs Mythix ORM that the defaultValue should be fetched and used as soon as a model instance is first initialized.

property Helpers::FLAG_ON_INSERT: number = 0x02

This flag informs Mythix ORM that the defaultValue should only be used on INSERT operations.

property Helpers::FLAG_ON_STORE: number = 0x06

This flag informs Mythix ORM that the defaultValue should only be used on INSERT and UPDATE operations.

property Helpers::FLAG_ON_UPDATE: number = 0x04

This flag informs Mythix ORM that the defaultValue should only be used on UPDATE operations. This is used for example by Types.DATE.Defaults.NOW.UPDATE.

property Helpers::FLAG_REMOTE: number = 0x10

This flag informs Mythix ORM that the defaultValue is provided by the database itself. For example the Types.BIGINT.Defaults.AUTO_INCREMENT type uses this flag.