Couchbase 节点 Js sdk 连接

Question

我正在尝试连接我的 couchbase 服务器，但是当我尝试在我的 express.js 应用上的 app.js 上创建连接实例时收到警告消息。

这里是 app.js

const express = require('express');
const bodyParser = require('body-parser');
const couchbase = require('couchbase');

const app = express();
const userRoutes = require('./routes/route');


app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: true}));

//COUCHBASE CONNECTION
const cluster = couchbase.connect('couchbase://localhost', {username: 'admin', password: '5121451214'},(err,cluster) => { 
    const bucket =  cluster.bucket('test_data_bucket');
    module.exports.bucket = bucket;
}); 



app.use('/',userRoutes);

app.listen(process.env.port || 3000);

console.log('Web Server is listening at port '+ (process.env.port || 3000));

这是我的AutherModel

const N1qlQuery = require('couchbase').N1qlQuery;
const data_bucket = require('../app').bucket;


function AuthorModel (){}

AuthorModel.getAll = function (callback)
{
    data_bucket.get('invoice_32212100000218', (err, res) => {
        if(error)
        {
            return callback(error,null);
        }

        callback(null,res);
    });
}


module.exports.AuthorModel = AuthorModel;

当我运行 node app.js 时出现此错误

node:2410417) Warning: Accessing non-existent property 'bucket' of module exports inside circular dependency
(Use `node --trace-warnings ...` to show where the warning was created)

//更改后的结果

connection.js

const couchbase = require('couchbase');

//COUCHBASE CONNECTION
couchbase.connect('couchbase://localhost', {username: 'admin', password: '5121451214'},(err,cluster) => {
  const bucket =  cluster.bucket('test_data_bucket');
  const defautScope = bucket.scope('_default');
  const defaultCollection = defautScope.collection('_default');

  module.exports.bucket = bucket;
  module.exports.cluster = cluster;
  module.exports.defaultCollection = defaultCollection;
});

author.js 模型

 const connection = require('../config/connection');
    
    const data_bucket = connection.bucket;
    const data_cluster = connection.cluster;
    const data_collection = connection.defaultCollection;
    
    
    module.exports = {
        getUsers  ()
        {
            const data = data_collection.get('invoice_32212100000218', (err, res) => {
                console.log(res);
            });
    
            return 'Hello from express';
        }
     }

收到此错误

TypeError: Cannot read properties of undefined (reading 'get')

Answer 1

循环依赖警告很可能是因为您正在从app.js 导出存储桶，需要在您的模型中使用它，它也可能包含在app.js 的某处，从而形成循环依赖。

要解决此问题，我建议将连接代码移动到单独的文件中，以便您可以在模型和路由中需要它的任何地方使用它。

重要提示：如果您使用的是 Node.js SDK 3.0 或更高版本，则需要在集合级别对象上调用.get()，而不是在存储桶上。您可以轻松地从连接代码中导出所需的集合。请参阅以下使用默认范围和集合的连接文件示例：

// connection.js
const couchbase = require('couchbase')

//COUCHBASE CONNECTION
const cluster = couchbase.connect('couchbase://localhost', {username: 'admin', password: '5121451214'},(err,cluster) => {
  const bucket =  cluster.bucket('test_data_bucket');
  const defautScope = bucket.scope('_default');
  const defaultCollection = defautScope.collection('_default')

  module.exports.bucket = bucket;
  module.exports.cluster = cluster;
  module.exports.defaultCollection = defaultCollection;
});

然后，您可以轻松地在模型中要求 connection.js 并根据需要获取存储桶、集群或集合级别的对象：

const connection = require('../connection');

const data_bucket = connection.bucket;
const data_cluster = connection.cluster;
const data_collection = connection.defaultCollection;