Node.js MongoDB
Deleting the documents
Delete Document
To delete a document as db.collection.deleteOne() method is
called. This method deletes only one document. The first parameter of the deleteOne() method is a query object that defines
the document to be deleted.
db.collection.deleteOne( <filter>, { writeConcern: <document>, collation: <document> } )
- The filter is a document provides deletion criteria using query operators. An empty document { } can be to delete the first document in the collection.
- writeConcern document is used to represent the write concern and it is optional.
- collation is a document used to provide the collation for the operation.
If the query finds multiple documents, then the first document will be deleted only.
(if you haven't idea about Node.js MongoDB create a collection, insert data and find data see previous tutorials)
For example,
const MongoClient = require('mongodb').MongoClient; const url = "mongodb://localhost:27017/"; MongoClient.connect(url, function(error, database) { if (error) throw error; var dbo = database.db("testdb"); var query={};//delete first document dbo.collection("employee").deleteOne(query,function(error, obj) { if (error) throw error; console.log('First document deleted successfully'); database.close(); }); }); Output: First document deleted successfully
deleting a document by field name.
const MongoClient = require('mongodb').MongoClient; const url = "mongodb://localhost:27017/"; MongoClient.connect(url, function(error, database) { if (error) throw error; var dbo = database.db("testdb"); var query={name:'Krish'};//delete by field document dbo.collection("employee").deleteOne(query,function(error, obj) { if (error) throw error; console.log(obj.result.n+' documents deleted successfully'); database.close(); }); });
Deleting Many documents
db.collection.deleteMany() method can be used to remove all the documents found by the query.
db.collection.deleteMany( <filter>, { writeConcern: <document>, collation: <document> } )
- The filter is a document provides deletion criteria using query operators. An empty document { } will delete all the documents in the collection.
- writeConcern document is used to represent the write concern and it is optional.
- collation is a document used to provide the collation for the operation.
If the query finds multiple documents, then all the documents will be deleted.
For example,
const MongoClient = require('mongodb').MongoClient; const url = "mongodb://localhost:27017/"; MongoClient.connect(url, function(error, database) { if (error) throw error; var dbo = database.db("testdb"); var query={salary:{$gte:'13000'}};//delete more than one documents dbo.collection("employee").deleteMany(query,function(error, obj) { if (error) throw error; console.log(obj.result.n+' documents deleted successfully'); database.close(); }); }); Output: 4 documents deleted successfully
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