- What is auto configuration ?
Wednesday, July 3, 2019
Tuesday, July 2, 2019
ReferenceError: MongoClient is not defined
Hi Guys ,
In this blog I will share information related to error : ReferenceError: MongoClient is not defined .
This error is related to the node.js code which is trying to connect to the database . To fix this check the following lines of code highlighted in yellow . You need to make sure module mongodb is imported and the MongoClient is referenced using the variable .
In this blog I will share information related to error : ReferenceError: MongoClient is not defined .
This error is related to the node.js code which is trying to connect to the database . To fix this check the following lines of code highlighted in yellow . You need to make sure module mongodb is imported and the MongoClient is referenced using the variable .
var mongo = require('mongodb'); | |
var url = "mongodb://localhost:27017/qanda"; | |
mongo.MongoClient.connect(url, function(err, db) { | |
if (err) throw err; | |
console.log("Database created!"); | |
db.close(); | |
}); |
Please make changes to the code and retest . Hope this will help you in resolving this issue .
MongoNetworkError: failed to connect to server MongoNetworkError: connect ECONNREFUSED
Hi Guys ,
You might have faced an error like MongoNetworkError: failed to connect to server [localhost:27017] on first connect [MongoNetworkError: connect ECONNREFUSED 127.0.0.1:27017]
We generally face this error when the database server is down , if you bring the database server up you will not face this error .
The full error is as follows :
(node:15564) DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.
F:\\study\nodejs\node_modules\mongodb\lib\topologies\server.js:240
throw err;
^
MongoNetworkError: failed to connect to server [localhost:27017] on first connect [MongoNetworkError: connect ECONNREFUSED 127.0.0.1:27017]
at Pool.<anonymous> (F:\\study\nodejs\node_modules\mongodb-core\lib\topologies\server.js:431:11)
at emitOne (events.js:116:13)
at Pool.emit (events.js:211:7)
at connect (F:\\study\nodejs\node_modules\mongodb-core\lib\connection\pool.js:557:14)
at makeConnection (F:\\study\nodejs\node_modules\mongodb-core\lib\connection\connect.js:39:11)
at callback (F:\\study\nodejs\node_modules\mongodb-core\lib\connection\connect.js:261:5)
at Socket.err (F:\\study\nodejs\node_modules\mongodb-core\lib\connection\connect.js:286:7)
at Object.onceWrapper (events.js:315:30)
at emitOne (events.js:116:13)
at Socket.emit (events.js:211:7)
The code snipped to connect to mongo db is as follows :
var mongo = require('mongodb'); | |
var url = "mongodb://localhost:27017/qanda"; | |
mongo.MongoClient.connect(url, function(err, db) { | |
if (err) throw err; | |
console.log("Database created!"); | |
db.close(); | |
}); |
Saturday, June 15, 2019
Sunday, June 9, 2019
Groovy Interview Questions
Important Interview Question in Groovy .
- Compare Java with Apache Groovy
- Groovy is a scripting language
- Less syntax
- default access modifier is public
- automatic getters and setters
- does not support ARM introduced in java 7
- allows variable substitution inside double quotes
- does not support anonymous inner class , lambda , use closure instead .
- groovy supports operator overloading
- What is AST transformations.
the ability to customize the Abstract Syntax Tree representing your programs before the compiler walks this tree to generate Java bytecode .
- Explain closure in groovy
{ [closureParameters -> ] statements }
- Explain GRAPE
Grape helps you download and cache external dependencies from within your script with a set of simple annotations.
@Grab('org.apache.httpcomponents:httpclient:4.2.1')
- What is the use of @GrabResolver
By default GRAPE uses Maven Central Repository , if we need to add our own repository we can use @GrabResolver .
Friday, May 17, 2019
Java Architect interview questions
- What are the 4 architecture domain TOGAF deal with ?
- business
- data
- application
- technology
- What is TOGAF ADM ?
It provides a tested and repeatable process for developing architectures .
- What are the phases within the ADM .
- preliminary
- architecture vision
- business architecture
- information system architecture
- technology architecture
- opportunities and solution
- migration planning
- implementation governance
- architecture change management
- requirement management
- What are the SOLID principles?
- Explain encryption in Java
Create key object using secret key spec passing key and algorithm
Cipher.getinstance blowfish
Set mode encrypt / decrypt
Cipher.dofinal//encrypted
Base64.encode // encoded
- A method is defined with return type string , I do not want to return anything but still want the method to compile , how can I achieve that ?
- How to access private variables of a class ?
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