Blob data from Oracle to text file using python

Question

I have been trying to get the blob data from oracle into a text file using Python. I couldn’t find the answer on any of the other links.

Below is my code :

sql_string = """select 
   event_id
   ,blob_length
   ,blob field
from table"""

  cur.execute(sql_string)
    path = "P:/Folders/"

    for row in cur:
        filename = path +  "notes_" + str(row[0]) + "_" + str(row[1]) + ".txt"      
        f = codecs.open(filename, encoding='utf-8', mode='wb+')
        f.write(row[2])
        f.close()

I get the below error

TypeError: utf_8_encode() argument 1 must be str, not cx_Oracle.LOB

I have tried a few other ways but the problem is that even other approaches that I’ve seen only handle strings and not blobs.

Asked By: Doodle

||

Source

Answer 1

You have to use the cx_oracle.LOB.read() method to get the content of the LOB object:

f.write(row[2].read())

Answered By: blhsing

Answer 2

Implemented what @blhsing suggested and it worked out perfectly

    for row in cur:
        filename = path +  "notes_" + str(row[0]) + "_" + str(row[1]) + ".txt"      
        print(row[2].read())
        f = open(filename, "wb")
        f.write(row[2].read())
        f.close()

Answered By: Doodle

Answer 3

If your LOBs are small enough to fit in memory you’ll get better performance if you fetch BLOBs as LONG_BINARY (and use LONG_STRING for CLOBs):

def OutputTypeHandler(cursor, name, defaultType, size, precision, scale):
    if defaultType == cx_Oracle.CLOB:
        return cursor.var(cx_Oracle.LONG_STRING, arraysize = cursor.arraysize)
    if defaultType == cx_Oracle.BLOB:
        return cursor.var(cx_Oracle.LONG_BINARY, arraysize = cursor.arraysize)

See the cx_Oracle example at https://github.com/oracle/python-cx_Oracle/blob/master/samples/ReturnLobsAsStrings.py

Answered By: Christopher Jones

Answer 4

Exporting as TSV (tab separated file) from DataGrip or similar tools, you can convert the hex-data of the blob to Python blob data this way:

import binascii
hexContent = blobContent[1:-1]
blob = binascii.unhexlify(hexContent)

Then you can save it to a file (remember ‘wb’ to save as blob), or work with it as normal blob in other ways

Answered By: Punnerud

Blob data from Oracle to text file using python

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