// Import or include PouchDB library
const PouchDB = require('pouchdb');
// Create a new instance of PouchDB with the desired database name
const myDatabase = new PouchDB('my_database_name');
// Optionally, you can provide additional options when creating the database
// For example, to specify a different storage backend:
// const myDatabase = new PouchDB('my_database_name', {adapter: 'leveldb'});?require() or ES6 import.PouchDB constructor and passing the desired name for the database as a parameter. This will create a new database with the specified name.leveldb', 'indexeddb', 'websql', etc.) or other settings.// Import PouchDB library
const PouchDB = require('pouchdb');
// Create a new PouchDB instance
const myDatabase = new PouchDB('my_database_name');?PouchDB instance, you can use its APIs to perform various operations such as storing, querying, and replicating data.put() method, retrieve documents using the get() method, and query data using the find() method.// Add a document to the database
myDatabase.put({
_id: 'my_document_id',
name: 'John Doe',
age: 30
}).then(response => {
console.log('Document added:', response);
}).catch(error => {
console.error('Error adding document:', error);
});
// Retrieve a document from the database
myDatabase.get('my_document_id').then(document => {
console.log('Retrieved document:', document);
}).catch(error => {
console.error('Error retrieving document:', error);
});?db.info() method is used to get the information about the database. This method also accepts a callback function.db.info([callback]) ?info() method. Here the database name is my_database.//Requiring the package
var PouchDB = require('PouchDB');
//Creating the database object
var db = new PouchDB('my_database');
//Database information
db.info(function(err, info) {
if (err) {
return console.log(err);
} else {
console.log(info);
}
}); ?createIndex() method to create a full-text search index on a PouchDB database, and then use the search() method to perform full-text searches.
mapReduce() method to perform MapReduce queries on a PouchDB database, passing in the map and reduce functions.
db.destroy() method. It also accepts a callback function.db.destroy() ?db.destroy() method.//Requiring the package
var PouchDB = require('PouchDB');
//Creating the database object
var db = new PouchDB('my_database');
//deleting database
db.destroy(function (err, response) {
if (err) {
return console.log(err);
} else {
console.log ("Database Deleted");
}
}); ?//Requiring the package
var PouchDB = require('pouchdb');
//Creating the database object
var db = new PouchDB('http://localhost:5984/my_database');
//deleting database
db.destroy(function (err, response) {
if (err) {
return console.log(err);
} else {
console.log("Database Deleted");
}
}); ?db.put() method is used to create documents in PouchDB databases.db.put(document, callback) ?_rev is get generated. It is called revision marker. The _rev's value is a unique random number, which is changed every time we make changes to the document.db.put() method is used along with _rev value to update a document.
db.bulkDocs(docs, [options], [callback]) ?pouchdb-find plugin can be used:pouchdb-find plugin either via npm or by including it directly in your HTML file using a script tag.npm install pouchdb-find?pouchdb-find plugin and add it to your PouchDB instance.const PouchDB = require('pouchdb');
PouchDB.plugin(require('pouchdb-find'));?// Create indexes on fields you want to query
db.createIndex({
index: { fields: ['name'] }
});?find() method to perform queries on the database. Queries are specified using a MongoDB-like query syntax.// Perform a query to find documents with a specific field value
db.find({
selector: { name: 'John' }
}).then(result => {
console.log('Query result:', result);
}).catch(error => {
console.error('Query error:', error);
});?pouchdb-find plugin supports a variety of query operators and options, allowing you to perform complex queries such as range queries, logical operators, sorting, limiting results, and more.// Perform a query with advanced options
db.find({
selector: { age: { $gte: 18 } },
sort: [{ age: 'desc' }],
limit: 10
}).then(result => {
console.log('Advanced query result:', result);
}).catch(error => {
console.error('Advanced query error:', error);
});?updateIndex() and getIndexes() methods.// Update or rebuild indexes
db.updateIndex().then(() => {
console.log('Indexes updated');
}).catch(error => {
console.error('Index update error:', error);
});?getAttachment() method. This method allows you to fetch the attachment content associated with a specific document and attachment ID. Here's how you can retrieve an attachment in PouchDB :// Assuming 'db' is your PouchDB instance and 'docId' is the ID of the document
// and 'attachmentId' is the ID of the attachment you want to retrieve
db.getAttachment(docId, attachmentId).then(function(blob) {
// 'blob' is the attachment content retrieved as a Blob object
// You can use this blob to manipulate or display the attachment content as needed
}).catch(function(err) {
console.log('Error retrieving attachment:', err);
});?db' with your PouchDB instance.docId' with the ID of the document that contains the attachment.attachmentId' with the ID of the attachment you want to retrieve.getAttachment() method returns a Promise that resolves with a Blob object containing the attachment content. You can then use this Blob object to manipulate or display the attachment content in your application as needed.catch() block.removeAttachment() method. This method allows you to remove an attachment associated with a specific document and attachment ID. Here's how you can delete an attachment in PouchDB:// Assuming 'db' is your PouchDB instance and 'docId' is the ID of the document
// and 'attachmentId' is the ID of the attachment you want to delete
db.removeAttachment(docId, attachmentId).then(function() {
// Attachment successfully removed
}).catch(function(err) {
console.log('Error deleting attachment:', err);
});?db' with your PouchDB instance.docId' with the ID of the document from which you want to remove the attachment.attachmentId' with the ID of the attachment you want to delete.removeAttachment() method returns a Promise that resolves once the attachment has been successfully removed from the document. If the removal encounters an error (e.g., if the document or attachment does not exist), the Promise will be rejected, and you can handle the error accordingly in the catch() block.emit() function.function mapFunction(doc) {
if (doc.type === 'user') {
emit(doc.name, 1);
}
}?function reduceFunction(keys, values, rereduce) {
return sum(values);
}?query() method to execute MapReduce queries on the database. You can specify the Map and Reduce functions, as well as additional options such as key ranges and sorting criteria.db.query({
map: mapFunction,
reduce: reduceFunction,
group: true
}).then(function(result) {
console.log('Query result:', result);
}).catch(function(err) {
console.error('Query error:', err);
});?db.query({
map: mapFunction,
reduce: reduceFunction,
group: true,
descending: true
}).then(function(result) {
console.log('Query result:', result);
}).catch(function(err) {
console.error('Query error:', err);
});?pouchdb-upsert and pouchdb-find are both plugins for PouchDB that serve different purposes and provide different functionalities. Here's a comparison of the two plugins:pouchdb-upsert is a plugin for PouchDB that provides an "upsert" (update or insert) functionality for documents in the database.upsert() method provided by the pouchdb-upsert plugin allows you to perform upsert operations on documents using a single API call.// Example of using pouchdb-upsert to update or insert a document
db.upsert('doc_id', function(doc) {
// Update the existing document or create a new document
doc.name = 'John Doe';
return doc;
}).then(function(response) {
console.log('Upsert successful:', response);
}).catch(function(error) {
console.error('Upsert error:', error);
});?pouchdb-find is a plugin for PouchDB that provides advanced querying and indexing capabilities for documents in the database.query() method provided by the pouchdb-find plugin allows you to perform complex queries on the database using a MongoDB-like query syntax.pouchdb-find is useful for scenarios where you need to perform sophisticated queries on the database to retrieve subsets of documents that match certain criteria.// Example of using pouchdb-find to perform a query
db.find({
selector: { age: { $gte: 18 } },
sort: ['age']
}).then(function(result) {
console.log('Query result:', result);
}).catch(function(error) {
console.error('Query error:', error);
});?createIndex() method to create indexes on specific fields or combinations of fields.bulkDocs() method to perform batch operations on documents.PouchDB CORS Plugin" that is officially recognized or maintained by the PouchDB project. CORS (Cross-Origin Resource Sharing) issues are typically handled at the server level, and PouchDB itself doesn't explicitly provide a plugin specifically for CORS.replicate() method to replicate data between a PouchDB database and a remote IBM Cloudant server.