Converting BLOB, stored on a database, to an image on an HTML website
Solution 1
image is stored in database in binary format so once it comes to server using decode function to get it back to image
image.decode('base64')
this will convert your blob to image
Solution 2
Depending on how its encoded, you can also possibly just use a Data URI for the image. Something like this might work if they are encoded as base64 PNGs.
<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAADIA..." />
As @Alok says, you might need to first convert it from binary blob to base64, then use the Data URI.
Solution 3
Well, you can either return an HTML response, and use a combination of the existing answers, or you can just return an image/jpeg
response, and dump the BLOB directly to stdout, with something like this...
def showFile():
# do SQL to retrieve blob where filename
conn, cursor = getConnectionAndCursor()
sql = """
select data
from upload
where id=1
"""
cursor.execute(sql)
data = cursor.fetchone()
blob = data[0]
print blob
if __name__ == "__main__":
form = cgi.FieldStorage()
if "show_file" in form:
print "Content-Type: image/jpeg"
print
showFile()
...but it depends on what you're trying to achieve.
Solution 4
It depends what you need to accomplish.
Single image on the HTML page.
1.1 Best approach is to use it with Content-Type: image/jpeg (if it's jpeg)
import sys def showFile(blob): print "Content-Type: image/jpeg\r\n" sys.stdout.flush() print sys.stdout.buffer.write(image) def getFile(): conn, cursor = getConnectionAndCursor() sql = """ select data from upload where id=1 """ cursor.execute(sql) data = cursor.fetchone() blob = data[0] return blob if __name__ == "__main__": form = cgi.FieldStorage() if "show_file" in form: image = getFile() showFile(image)
Why is the best approach? Because you can use requested url that triggers this script as source of an image tag in html file
Multiple images on one html page.
2.1 Convert blob in base64
import base64 blob = base64.b64encode(blob).decode('utf-8') # You need to decode it to get pure string and use it later in <img>
After you converted it you can place it.
print(f"<img src="data:image/jpeg;base64,{blob}>")
Notes: I am using python3.8 for the second example. I am assuming you are using cgi module.
user2332223
Updated on January 05, 2021Comments
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user2332223 over 3 years
This is my first question.
I am having users upload their own image to a database. That image is stored as a BLOB.
I was able to do this successfully. I am using MySQL for the database.
The part I am having trouble with is displaying that BLOB as an image on the website when its called upon.
Right now only the Binary data, lots of weird symbols are being displayed. I think its a problem with the HTTP header. Right now its in :
print "Content-Type: text/html"
I've tried:
print "Content-Type: image/jpeg"
I am using Python to connect with the database and write the HTML.
Edit: Code:
def showFile(): # do SQL to retrieve blob where filename conn, cursor = getConnectionAndCursor() sql = """ select data from upload where id=1 """ cursor.execute(sql) data = cursor.fetchone() blob = data[0] print "<hr>" print "This is what I'm trying" print """<img src="data:image/jpeg;base64,%s/>""" % data ###################################################################### if __name__ == "__main__": form = cgi.FieldStorage() if "show_file" in form: print "Content-Type: text/html" print printHeaders("Image upload example") showFile() printFooter()
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user2332223 about 11 yearsI gave this a try and decoding didn't work, but when I retrieved the BLOB from the database encoding it to base 64 and using the HTML that Reptilcus suggested work. Thank You
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user2332223 about 11 yearsI tried what Alok suggested, but when I retrieved the BLOB from the database encoding it to base 64 and using the HTML you suggested work. Thank You
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reptilicus about 11 yearsCool, if it worked then please upvote this answer so that others will be able to use it if they have the same problem.