如何在 nodejs 中的控制器中访问常量变量

Question

>我在模型文件中定义了一个常量变量，并尝试在将数据插入表时访问此常量变量，然后它显示未定义。我正在使用sequlaize ORM和nodejs。我想为状态定义三个值，例如活动 = 1、非活动 = 2、已删除 = 3，或者是否有任何其他解决方案来定义它。我正在使用续集ORM 4+版本。

Model code is here
var Sequalize = require('sequelize');
var sequalize = require('../../config/db_config');
const ACTIVE = '1';
const INACTIVE = '2';
const DELETED = '3';
const User = sequalize.define('user',{
user_id_pk : {
type : Sequelize.INTEGER,
allowNull : false,
primaryKey : true,
autoIncrement : true
},
user_type : Sequelize.INTEGER,
first_name : Sequelize.STRING,
middle_name : Sequelize.STRING,
last_name : Sequelize.STRING,
password : Sequelize.STRING,
email : Sequelize.STRING,
mobile_no : Sequelize.STRING,
is_email_verified : {
type:Sequalize.INTEGER,
defaultValue : 0
},
gender : Sequelize.STRING,
profile_image: Sequelize.STRING,
dob : Sequelize.DATE,
is_active : Sequelize.STRING,
created_date : Sequelize.DATE,
created_by : Sequelize.INTEGER,
updated_date : Sequelize.DATE,
updated_by : Sequelize.INTEGER,
},{
timestamps: false,
paranoid: true,
underscored: true,
freezeTableName: true,
tableName: 'user',
createdAt:'created_date',
updatedAt:'updated_date'
});
User.sync({force:false}).then(() => {
console.log('Table is created!');    
}).catch(err => {
console.log('An error occur when table is created!');
});
module.exports = User;
Controller code is here 
userController.saveUser = function(req,res){
console.log(user.ACTIVE);return false;
user.findOrCreate({
where:{
first_name: req.body.first_name,
email: req.body.email,
boltt_code: req.body.boltt_code
},
defaults:{
first_name: req.body.fihhrst_name,
middle_name : 'Rajeev',
last_name : 'Varshney',
email: req.body.email,
boltt_code: req.body.boltt_code,
is_active : '1',
}
})
.spread( function(user, created) {
var msg = '';
if(created){
msg = 'User inserted successfully!';
}else{
msg = 'User already exist!';
}
res.status(200).send({error : false,message : msg2, data : user });
})
.catch((err) => {
console.log('Oops something wrong! ' + err);
});
};

Answer 1

如果你想在同一个文件中使用这些变量，你只需要声明它们并使用它。 如果要从另一个文件访问它们，则必须导出变量：

const ACTIVE = '1';
const INACTIVE = '2';
const DELETED = '3';
exports.ACTIVE = ACTIVE;
exports.INACTIVE = INACTIVE;
exports.DELETED = DELETED;

现在，您可以要求文件和访问变量。

Answer 2

We can initialize constant variable to model instance after creating the model instance. 
const ACTIVE = 1;
const INACTIVE = 2;
const DELETED = 3;
const user = sequelize.define('user',{..},{
});
User.ACTIVE = ACTIVE;
User.INACTIVE = INACTIVE;
User.DELETED = DELETED;
module.exports = User;

Answer 3

在ModelCore中.js文件不仅导出用户，还导出常量：

// ModelCore.js
var Sequalize = require('sequelize');
var sequalize = require('../../config/db_config');
const ACTIVE = '1';
const INACTIVE = '2';
const DELETED = '3';
const User = sequalize.define('user', {...});
module.exports = {
User,
CODES: {
ACTIVE,
INACTIVE,
DELETED
}
}

现在将其导入到您的控制器代码中.js：

// ControllerCode.js
const modelCore = require('./path/to/ModelCore');
const user = modelCore.User;
const {CODES} = modelCore;
//Using codes now should work
console.log(CODES.ACTIVE);
console.log(CODES.INACTIVE);
console.log(CODES.DELETED);
// Rest of your Controller code...