書架ORM的MySQL如何選擇列1，列2的別名

Question

在原MySQL查詢，我有這樣的事情：

Select total_sales - over_head_costs As net_sales from departments; 

我怎樣才能實現與書架/ knex查詢同樣的事情？理想情況下不使用knex.raw。

我嘗試包括以下內容：

let Department = bookshelf.Model.extend({ 
    tableName: 'departments', 
    idAttribute: 'department_id', 
},{ 
    getDepartments: function(){ 
    return this.fetchAll({columns: ['department_id', 'department_name', 'over_head_costs', 'total_sales - over_head_costs AS net_sales']}) 
    .then(models=>models.toJSON()); 
    }, 
}); 

Answer 1

書架不具備此功能，但它帶來的一個插件是：Virtuals 。無需安裝任何東西，只需在使用bookshelf.plugin('virtuals')加載書架後立即加載它。

你的模型應該再像：

const Department = bookshelf.Model.extend({ 
    tableName: 'departments', 
    idAttribute: 'department_id', 
    virtuals: { 
    net_sales: function() { 
     return this.get('total_sales') - this.get('over_head_costs'); 
    } 
    } 
},{ 
    getDepartments: function(){ 
    return this.fetchAll({columns: ['department_id', 'department_name', 'over_head_costs', 'net_sales']}) 
    .then(models=>models.toJSON()); 
    }, 
});