PouchDB is an open-source JavaScript database inspired by Apache CouchDB that is designed to run well within the browser.
In this article , I will be explaining about the installation of pouchDB and also some basic CRUD operations involved.
Before playing with database we need to install it , below I have mentioned the installation methods for the database.
Installation
For installing pouchDB in your system , you can either include the cdn or install using package manager like npm , bower etc.
Using npm :
npm install --save pouchdb after installing using , you have to use require inorder to use pouchDB for your application.
let PouchDB = require('pouchdb'); let db = new PouchDB('my_database'); Now the installation part is done , we will see some basic CRUD operations using pouchDB. You can also refer to pouchDB’s official documentation, mentioned the link below,
Getting started Guide with PouchDB
WORKING WITH DATABASE :
CREATING THE DATABASE :
You can create the local database using PouchDB constructor. Method goes as follows
let PouchDB = require('pouchdb'); let db = new PouchDB('test_db1'); console.log ("Database created Successfully."); GETTING THE INFO ABOUT THE DATABASE :
You can get the information about the database using info() method
let PouchDB = require('pouchdb'); let db = new PouchDB('test_db1'); console.log ("Database created Successfully."); //You can get the basic information about the database using the method named info() db.info((err,info) => { if(!err){ console.log(info) } }); Now if you run the file from command line , you will be getting the output as below,
{ adapter:"idb" auto_compaction:false db_name:"test_db222" doc_count:0 idb_attachment_format:"binary" update_seq:0 } DELETING THE DATABASE :
You can delete the database using db.destroy method. Example for deleting the method goes as follows
//Requiring the package var PouchDB = require('PouchDB'); //Creating the database object var db = new PouchDB('test_db222'); //deleting database db.destroy(function (err, response) { if (err) { return console.log(err); } else { console.log ("Database Deleted"); } }); WORKING WITH DOCUMENTS :
PouchDB is a no-sql database , so instead of storing the data in relational form , data is stored in the form of documents. You can perform the basic CRUD operations in documents.
Comparison chart from pouch db official docs
CREATING A DOCUMENT :
Documents can be created using db.put method.
let PouchDB = require('pouchdb'); let db = new PouchDB('test_db222'); console.log ("Database created Successfully."); //creating a new database //Preparing the document let doc = { _id : '002', name: 'Karthi', age : 23, designation : 'Designer' } //Inserting Document db.put(doc, function(err, response) { if (err) { return console.log(err); } else { console.log("Document created Successfully",response); } }); You will get the following message from the console if you run the program
Document created successfully //Document created Successfully {ok: true, id: "003", rev: "1-325eb8a7f91c4035a033fca9f5c32f52"} If you try to add the same document , you will get the following error
//CustomPouchError { status: 409, name: "conflict", message: "Document update conflict", error: true, id: "003" } DISPLAYING THE DOCUMENT :
You can display the document using db.get which will take a key as argument which is supposed to be unique.
let PouchDB = require('pouchdb'); let db = new PouchDB('test_db222'); //success message console.log ("Database created Successfully."); //getting the document from the database db.get('002',(err,info)=>{ if(!err){ console.log("db value",info) } else{ console.log("err field",err) } }); You will get the output as follows
{name: "Karthi", age: 23, designation: "Designer", _id: "002", _rev: "1-38fd304f70974adeb370e3cf8bc89f39"} UNDERSTANDING REVISIONS (_rev)
The new field _rev is called revision-marker which will be updated whenever you create or update the documents.We will be using _rev when we are updating the documents.
UPDATING THE DOCUMENTS :
So inorder to update the documents , you need to get the _rev but you don’t need to manually add the _rev as it is already present in the doc which we will be fetching.
let PouchDB = require('pouchdb'); let db = new PouchDB('test_db222'); //creating the db console.log ("Database created Successfully."); //get the data and update db.get('002').then(function (doc) { // update their age doc.age = 40; // put them back return db.put(doc); }).then(function () { // fetch data again return db.get('002'); }).then(function (doc) { console.log(doc); }); Now you will get the following result in the console
{name: "Karthi", age: 40, designation: "Designer", _id: "002", _rev: "3-9a7dac1a7b1a4332b9d44d9dd5dca757"} DELETING THE DOCUMENTS:
You can use the db.delete() method to delete the documents in the database.
let PouchDB = require('pouchdb'); //require the package let db = new PouchDB('test_db222'); //created the db console.log ("Database created Successfully."); //get the doc db.get('002').then(function (doc) { // remove the doc return db.remove(doc._id, doc._rev); }).then(function(err,info){ //print the data if(!err){ console.log("info",info) }else{ console.log(err) } }); You will get the following output with result
{ ok: true, id: "002", rev: "4-d6f058da696f4760b31492c9f00ad1ec" } Conclusion:
That's pretty much it. Thank you for taking the time to read the blog post. If you found the post useful , add ❤️ to it and let me know if I have missed something in the comments section. Feedback on the blog are most welcome.
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