Retrieve stored image from mongodb using python

Question

from pymongo import MongoClient
from bson.objectid import ObjectId
import numpy as np
import gridfs 

import os,os.path
i=0
try:
    for file in os.listdir("/Users/sarthakgupta/Desktop/sae/Images"):
        if (file.endswith(".png") | file.endswith(".jpg")):
            filename = "/Users/sarthakgupta/Desktop/sae/Images/"+file
            datafile =  open(filename,"rb")
            thedata = datafile.read()
            datafile.close()


            c = MongoClient()
            i=i+1
            db = c.trial5
            fs = gridfs.GridFS(db)
            t = "class"+str(i)


            stored = fs.put(thedata,filename=q)

except IOError:
    print("Image file %s not found" %datafile)
    raise SystemExit

I stored image in a mongo db . Now i want to retrieve those images from database by the filename and to store the image(or pixels) of same filename in an array or list. Suppose if there is 2 images with filename "class1",then they should be in one array.

Hope my answer in another question may help you. stackoverflow.com/questions/22077720/… — CoderYel
– CoderYel, Commented Mar 22, 2017 at 11:28

A. Jesse Jiryu Davis · Accepted Answer · 2017-02-16 16:35:03Z

2

Create your fs variable like before, and:

data = fs.get_last_version(filename).read()

You could also query for a list of files like:

from bson import Regex
for f in fs.find({'filename': Regex(r'.*\.(png|jpg)')):
    data = f.read()

Also, a comment about your code: it's very slow to recreate the MongoClient and GridFS instances for every iteration of your loop. Create them once before you start looping, and reuse them.

answered Feb 16, 2017 at 16:35

A. Jesse Jiryu Davis

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5 Comments

Sarthak Gupta Over a year ago

When i use : 'data = fs.get_last_version(filename='class3') print(data)' i get the output : <gridfs.grid_file.GridOut object at 0x105279e80> . What does this mean ? and when i use 'data = fs.get_last_version(filename='class3').read() print(data)'. I get the output "b'\xff\xd8\xff\xe0\x00\x10JFIF\x00\x01\x01\x00\x00H\x00H\x00\x00\xff\xe1\x00XExif\x00\x00MM\x00*\x00\x00\x00\x08\x00\x02\x0......" in this form. How can i use this output ?.. Thanks for the suggestion

A. Jesse Jiryu Davis Over a year ago

"data" is the byte contents of the image. You could save those contents to a file named "image.jpg" or do whatever you want with them.

Sarthak Gupta Over a year ago

But when i tried to display the image using open cv , i get an error " a bytes-like object is required, not 'GridOut' " . Here's my code. nparr = np.fromstring(data1, np.uint8) img_np = cv2.imdecode(nparr, cv2.CV_LOAD_IMAGE_COLOR) print(img_np)

A. Jesse Jiryu Davis Over a year ago

f is a GridOut object. f.read() is the contents of the image. Pass f.read() to OpenCV.

Yash Agrawal Over a year ago

the for loop method is still showing error illegal expression on Regex.

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