Oracle - Handling Exceptions to Oracle Queries

In Oracle DB, if we already have data in the table and would like to use exceptions to handle errors, please follow below approach:

declare
 e_col_exists exception;
 pragma exception_init(e_col_exists,-1430);
 e_invalid_identifier exception;
 pragma exception_init(e_invalid_identifier,-904);
begin
  begin
    execute immediate 'alter table tbl_questions add value_new varchar2(4000 CHAR) null';
    exception
      when e_col_exists then
        null;
  end;
  begin
    execute immediate 'update tbl_questions set value_new = value';
  end;
  begin
    execute immediate 'alter table tbl_questions drop column value';
    exception
      when e_invalid_identifier then
        null;
  end;
  begin
    execute immediate 'alter table tbl_questions rename column value_new to value';
    exception
      when e_invalid_identifier then
        null;
  end;
end;  
/
------
Explanation:
1. e_col_exists exception:
This exception is likely used to handle situations where a column referenced in your code doesn't actually exist in the table you're trying to access.
The pragma exception_init line associates the exception with the error code -1430. This error code typically corresponds to the ORA-01430 error message, which indicates "column does not exist".
2. e_invalid_identifier exception:
This exception is likely used to handle situations where an identifier (e.g., a variable name, column name, etc.) used in your code is invalid or doesn't follow the naming conventions.
The pragma exception_init line associates the exception with the error code -904. This error code typically corresponds to the ORA-00904 error message, which indicates "invalid identifier".
By defining these custom exceptions, you can make your code more robust and easier to maintain. When either of these exceptions is raised, your code can handle the error gracefully instead of crashing or producing unexpected results.
Here are some additional points to note:
You can define custom exceptions to handle any specific error conditions you want to anticipate in your code.
It's generally considered good practice to define custom exceptions for situations that are specific to your application logic and not already covered by standard Oracle error codes.
You can use exception handlers to trap these custom exceptions and take appropriate actions when they occur.
I hope this explanation helps! Feel free to ask if you have any other questions.

Python method to convert Array to Unique Array

Python Function to filter array and create unique array list

def array_unique(array_list):
    list = np.array(array_list)
    return np.unique(list)

Python - To read file content & write into a file

from pathlib import Path


# Read file content
def read_file():
    test_file = "example/you_test_file.txt"

    contents = Path(test_file).read_text()

    print (contents) # print file content

    #debug(contents) # use can also use my custom debug method to see log in file



# To write message to file for debugging
def debug(message="", type="w+"):
	filePath = "test/debug.txt" # don't forgot to create a empty file

    with open(filePath, type) as f:
        f.write(str(message) + "\n\n")
    f.close()
    

Simple bash stements to set values covering following two scenarios: 1. Set username/password variable if value passed on running the file 2. Or (step 1 doesn't pass values), set them on prompt arguments Create a login.sh file using the below content:

#!/bin/sh

# set -o errexit -o nounset -o xtrace

echo "Initialising Username/Password: "

if test "${1+x}"; then # Set values from inline statement
  username=$1
  password=$2  
else # Otherwise, set values from arguments
  read -p 'Username: ' username
  read -sp 'Password: ' password
fi

echo 'Username: ' $username '| Password: ' $password

1. First scenario, passing the values whilst running the file

$ sh login.sh nepal.user Pokhara123
Username:  nepal.user | Password:  Pokhara123

2. Second scenario, passing the values on prompt arguments

$ sh login.sh 

$ sh login.sh
Initialising Username/Password:
Username: nepal.user
Password: Pokhara123
Username:  nepal.user | Password:  Pokhara123

Build Dynamic Marshal_With in Flask (Python) based on conditions

To create a dynamic marshalling based on condition or parameter type, please follow the instruction below:

# Constants
MARSHELL_WITH_SCHEMAS = {
    "condition_1": Condition1Schema,
    "condition_2": Condition2Schema,
}


# To build dynamic marshalling based on report type
def selective_marshal_with():
    def decorator(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            condition_type = kwargs.get("condition_type", None)

            # Get marshalled with dynamic schema by condition type
            marshal_with_func = marshal_with(MARSHELL_WITH_SCHEMAS.get(condition_type, None))(func)

            return marshal_with_func(*args, **kwargs)

        return wrapper

    return decorator

# Actual class to connect view to URL
class MyViewClass(MethodResource, Resource):
    @doc(description="My View API", tags=["My View List"])
    @use_kwargs(MyQueryParams, location="query")
    @selective_marshal_with()
    @standard_api("My View List")
    def get(self, **kwargs):
        # you get code here....
    

The MyQueryParams can/should be in seperate schema file for e.g. rest/db/schema/my_view_schema.py

class MyQueryParams(Schema):
    """Query parameters for View List API."""

    condition_type = fields.Str(attribute="condition_type", required=True)

Hope it helps!

Count number of PDF file pages in PHP

Below function returns the number of pages count in PHP

function getPageCount(StreamInterface $stream): int
{
        $result = 0;

        $stream->rewind();

        while (! $stream->eof()) {
            $chunk = $stream->read(4096);

            //  looking for root node PDF 1.7+
            $found = \preg_match('/\/Type\s*?\/Pages(?:(?!\/Parent).)*\/Count\s?(?\d+)/', $chunk, $matches);

            if (0 < $found) {
                return (int) $matches['value'];
            }

            //  looking for root node PDF < 1.7
            $found = \preg_match('/\/Count\s?(?\d+)\s?\/Type\s*?\/Pages/', $chunk, $matches);

            if (0 < $found) {
                return (int) $matches['value'];
            }
            
            //  looking for root node PDF 1.7
            // Both regex1 & regex2 should work, but $regex2 is preferred.
            $regex1 = '/(?<=\/Type\s\/Pages\s(.*)\/Count\s)\d*/gs';
            $regex2 = '/\/Type\s*?\/Pages\s.*\/Count\s?(?\d+)/s';
            $found = \preg_match($regex2, $chunk, $matches);
            
            if (0 < $found) {
                return (int) $matches['value'];
            }

            //  looking for /Type/Page
            $found = \preg_match_all('/\/Type\s*?\/Page\s+/', $chunk, $matches);

            if (0 < $found) {
                $result += $found;
            }
        }

        $stream->rewind();

        return $result;
}

PHP Regex function to extract text between tags for a synopsis or intro text

The following method prepare the synopsis from the body and the second part is for unit tests:

Hope it helps!