add extracting pdf metadata tutorial

Author: x4nth055

README.md

@@ -160,6 +160,7 @@ This is a repository of all the tutorials of [The Python Code](https://www.thepy
     - [How to Encrypt and Decrypt PDF Files in Python](https://www.thepythoncode.com/article/encrypt-pdf-files-in-python). ([code](handling-pdf-files/encrypt-pdf))
     - [How to Merge PDF Files in Python](https://www.thepythoncode.com/article/merge-pdf-files-in-python). ([code](handling-pdf-files/pdf-merger))
     - [How to Sign PDF Files in Python](https://www.thepythoncode.com/article/sign-pdf-files-in-python). ([code](handling-pdf-files/pdf-signer))
+    - [How to Extract PDF Metadata in Python](https://www.thepythoncode.com/article/extract-pdf-metadata-in-python). ([code](handling-pdf-files/extract-pdf-metadata))
 
 - ### [Python for Multimedia](https://www.thepythoncode.com/topic/python-for-multimedia)
     - [How to Make a Screen Recorder in Python](https://www.thepythoncode.com/article/make-screen-recorder-python). ([code](general/screen-recorder))

handling-pdf-files/extract-pdf-metadata/README.md

@@ -0,0 +1 @@
+# [How to Extract PDF Metadata in Python](https://www.thepythoncode.com/article/extract-pdf-metadata-in-python)

handling-pdf-files/extract-pdf-metadata/bert-paper.pdf

@@ -0,0 +1,64 @@
+import pikepdf
+import datetime
+import re
+from dateutil.tz import tzutc, tzoffset
+import sys
+
+
+pdf_date_pattern = re.compile(''.join([
+    r"(D:)?",
+    r"(?P<year>\d\d\d\d)",
+    r"(?P<month>\d\d)",
+    r"(?P<day>\d\d)",
+    r"(?P<hour>\d\d)",
+    r"(?P<minute>\d\d)",
+    r"(?P<second>\d\d)",
+    r"(?P<tz_offset>[+-zZ])?",
+    r"(?P<tz_hour>\d\d)?",
+    r"'?(?P<tz_minute>\d\d)?'?"]))
+
+
+def transform_date(date_str):
+    """
+    Convert a pdf date such as "D:20120321183444+07'00'" into a usable datetime
+    http://www.verypdf.com/pdfinfoeditor/pdf-date-format.htm
+    (D:YYYYMMDDHHmmSSOHH'mm')
+    :param date_str: pdf date string
+    :return: datetime object
+    """
+    global pdf_date_pattern
+    match = re.match(pdf_date_pattern, date_str)
+    if match:
+        date_info = match.groupdict()
+
+        for k, v in date_info.items():  # transform values
+            if v is None:
+                pass
+            elif k == 'tz_offset':
+                date_info[k] = v.lower()  # so we can treat Z as z
+            else:
+                date_info[k] = int(v)
+
+        if date_info['tz_offset'] in ('z', None):  # UTC
+            date_info['tzinfo'] = tzutc()
+        else:
+            multiplier = 1 if date_info['tz_offset'] == '+' else -1
+            date_info['tzinfo'] = tzoffset(None, multiplier*(3600 * date_info['tz_hour'] + 60 * date_info['tz_minute']))
+
+        for k in ('tz_offset', 'tz_hour', 'tz_minute'):  # no longer needed
+            del date_info[k]
+
+        return datetime.datetime(**date_info)
+
+
+
+# get the target pdf file from the command-line arguments
+pdf_filename = sys.argv[1]
+# read the pdf file
+pdf = pikepdf.Pdf.open(pdf_filename)
+docinfo = pdf.docinfo
+for key, value in docinfo.items():
+    if str(value).startswith("D:"):
+        # pdf datetime format, convert to python datetime
+        value = transform_date(str(pdf.docinfo["/CreationDate"]))
+    print(key, ":", value)

handling-pdf-files/extract-pdf-metadata/extract_pdf_metadata.py

@@ -0,0 +1,10 @@
+import pikepdf
+import sys
+
+# get the target pdf file from the command-line arguments
+pdf_filename = sys.argv[1]
+# read the pdf file
+pdf = pikepdf.Pdf.open(pdf_filename)
+docinfo = pdf.docinfo
+for key, value in docinfo.items():
+    print(key, ":", value)

handling-pdf-files/extract-pdf-metadata/extract_pdf_metadata_simple.py

@@ -0,0 +1 @@
+pikepdf