Mongodatabase with Python for Students.pptx

MongoDB With Python
MongoDB is a document database with the scalability and flexibility that you want with the querying and
indexing that you need
Requirements:
Install MongoDB Community Server
Download Mongosh
Pip install pymongo
import pymongo

Creating a Database
 To create a database in MongoDB, start by creating a MongoClient object, then specify a
connection URL with the correct ip address and the name of the database you want to create.
 MongoDB will create the database if it does not exist, and make a connection to it.
import pymongo
myclient = pymongo.MongoClient("mongodb://localhost:27017/")
mydb = myclient["avanthi"]

Creating a Collection
A collection in MongoDB is the same as a table in SQL databases.
 To create a collection in MongoDB, use database object and specify the name of the collection you
want to create.
 MongoDB will create the collection if it does not exist.
import pymongo
mycol = mydb["customers"]

Insert Into Collection
 To insert a record, or document as it is called in MongoDB, into a collection, we use the insert_one()
method.
 The first parameter of the insert_one() method is a dictionary containing the name(s) and value(s) of
each field in the document you want to insert.
import pymongo
mydict = { “name”: “RKREDDY”, “address”: “Hyderabad”: “college”: “Avanthi”}
x = mycol.insert_one(mydict)

Insert Multiple Documents
 To insert multiple documents into a collection in MongoDB, we use the
insert_many() method.
 The first parameter of the insert_many() method is a list containing
dictionaries with the data you want to insert:

import pymongo
mylist = [
{ "name": "rkr", "address": "Nandhyal"},
{ "name": "Jyothi", "address": "Amaravathi"},
{ "name": "Ramya", "address": "Kmamareddy"},
{ "name": "Ramya", "address": "Siddipet"},
{ "name": "Sweety", "address": "Karimanagar"},
{ "name": "Anil", "address": "Kurnool"},
{ "name": "Vijay", "address": "DSNR"},
{ "name": "Madhu", "address": "Kakinada"}
]
x = mycol.insert_many(mylist)
#print list of the _id values of the inserted documents:
print(x.inserted_ids)

Find One
 In MongoDB we use the find() and find_one() methods to find data in a collection.
 Just like the SELECT statement is used to find data in a table in a MySQL database.
 To select data from a collection in MongoDB, we can use the find_one() method.
 The find_one() method returns the first occurrence in the selection.
import pymongo
x = mycol.find_one()
print(x)

Find All
 To select data from a table in MongoDB, we can also use the find() method.
 The find() method returns all occurrences in the selection.
 The first parameter of the find() method is a query object. In this example we use an empty
query object, which selects all documents in the collection.
import pymongo
for x in mycol.find():
print(x)

Return Only Some Fields
 The second parameter of the find() method is an object describing which fields to include in the
result.
 This parameter is optional, and if omitted, all fields will be included in the result.
import pymongo
for x in mycol.find({},{ "_id": 0, "name": 1, "address": 1 }):
print(x)

 You are not allowed to specify both 0 and 1 values in the same object
import pymongo
for x in mycol.find({},{ "address": 0 }):
print(x)

Filter the Result
 When finding documents in a collection, you can filter the result by using a query object.
 The first argument of the find() method is a query object, and is used to limit the search.
import pymongo
myquery = { "address": "kurnool" }
mydoc = mycol.find(myquery)
for x in mydoc:
print(x)

Advanced Query
 To make advanced queries you can use modifiers as values in the query object.
 E.g. to find the documents where the "address" field starts with the letter "S" or higher (alphabetically), use
the greater than modifier: {"$gt": "S"}:
import pymongo
myquery = { "address": { "$gt": "K" } }
for x in mydoc:
print(x)

 To find only the documents where the "address" field starts with the letter "S", use the regular
expression {"$regex": "^S"}:
import pymongo
myquery = { "address": { "$regex": "^R" } }
for x in mydoc:
print(x)

Sort the Result
 Use the sort() method to sort the result in ascending or descending order.
 The sort() method takes one parameter for "fieldname" and one parameter for "direction"
(ascending is the default direction).
import pymongo
mydb = myclient["aavanthi"]
mydoc = mycol.find().sort("name")
for x in mydoc:
print(x)

Sort Descending
 Use the value -1 as the second parameter to sort descending.
 sort("name", 1) #ascending
 sort("name", -1) #descending
import pymongo
mydoc = mycol.find().sort("name", -1)
for x in mydoc:
print(x)

Delete Document
 To delete one document, we use the delete_one() method.
 The first parameter of the delete_one() method is a query object defining which document to delete.
import pymongo
myquery = { "address": "Kurnool" }
mycol.delete_one(myquery)

Delete Many Documents
 To delete more than one document, use the delete_many() method.
import pymongo
myquery = { "address": {"$regex": "^S"} }
x = mycol.delete_many(myquery)
print(x.deleted_count, " documents deleted.")

Delete All Documents in a Collection
To delete all documents in a collection, pass an empty query object to the delete_many() method:
import pymongo
x = mycol.delete_many({})
print(x.deleted_count, " documents deleted.")

Delete Collection(DROP)
 You can delete a table, or collection as it is called in MongoDB, by using the drop() method.
import pymongo
mycol.drop()

Update Collection
 You can update a record, or document as it is called in MongoDB, by using the update_one()
method.
 The first parameter of the update_one() method is a query object defining which document to
update.
import pymongo
myquery = { "address": "Nandhyal" }
newvalues = { "$set": { "address": "Ongole" } }
mycol.update_one(myquery, newvalues)
#print "customers" after the update:
for x in mycol.find():
print(x)

Update Many
 To update all documents that meets the criteria of the query, use the update_many() method.
 Update all documents where the address starts with the letter "S":
import pymongo
myquery = { "address": { "$regex": "^K" } }
newvalues = { "$set": { "name": "Ramakrishna" } }
x = mycol.update_many(myquery, newvalues)
print(x.modified_count, "documents updated.")

Limit the Result
 To limit the result in MongoDB, we use the limit() method.
 The limit() method takes one parameter, a number defining how many documents to return.
 Consider you have a "customers" collection:
import pymongo
myresult = mycol.find().limit(5)
#print the result:
for x in myresult:
print(x)

Mongodatabase with Python for Students.pptx

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