The HasOne association in ExtJS needs some love - it would be nice if we could specify a 'name', which generates all of the necessary variables following a convention. This makes defining the association a lot less verbose Before and After examples are included.

1_OverrideToHasOne.js

// Apply an override to the HasOne association, allowing a 'name' parameter to generate the getter, setter, associationKey, and associatedName
Ext.override(Ext.data.association.HasOne, {
  constructor: function(config) {
    if (config.name ) {
      Ext.applyIf(config, {
        getterName: 'get' + Ext.String.capitalize(config.name),
        setterName: 'set' + Ext.String.capitalize(config.name),
        associationKey: config.name,
        associatedName: config.name
      })
    }
    this.callParent([config])
  }
})

2_Before.js

// BEFORE

// A JobPosition has a title (a field), a manager (a person), and an occupant (another person)
Ext.define('JobPosition', {
  extend: 'Ext.data.Model',
  fields: [
    { name: 'title', type: 'string' }
  ],
  hasOne: [
    { model: 'Person', getterName: 'getManager', setterName: 'setManager', associationKey: 'manager', associatedName: 'manager' },
    { model: 'Person', getterName: 'getOccupant', setterName: 'setOccupant', associationKey: 'occupant', associatedName: 'occupant' }
  ]
})
// a Person has a first and last name
Ext.define('Person', {
  extend: 'Ext.data.Model',
  fields: [
    { name: 'first', type: 'string' },
    { name: 'last', type: 'string' }
  ]
})

3_After.js

// AFTER

// A JobPosition has a title (a field), a manager (a person), and an occupant (another person)
Ext.define('JobPosition', {
  extend: 'Ext.data.Model',
  fields: [
    { name: 'title', type: 'string' }
  ],
  hasOne: [
    { model: 'Person', name: 'manager' },
    { model: 'Person', name: 'occupant' }
  ]
})
// a Person has a first and last name
Ext.define('Person', {
  extend: 'Ext.data.Model',
  fields: [
    { name: 'first', type: 'string' },
    { name: 'last', type: 'string' }
  ]
})