postgres-dynamic 0.0.3

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postgres-dynamic - Python-PostgreSQL Dynamic Query Builder

Postgres dynamic is a simple query builder developed for internal usage. It currently supports select, insert, update, and delete statements. The purpose of this library is for better managament and maintenance of the code used in our environment.

Parameter Format:

• connection_string: dict

  connection_string = {
      'PG_HOST': 'YOUR_CONNETION_HOST_ADDRESS',
      'PG_PORT': 'YOUR_CONNECTION_PORT',
      'PG_DATABASE': 'YOUR_CONNECTION_DATABASE_NAME',
      'PG_USER': 'YOUR_CONNECTION_USERNAME',
      'PG_PASSWORD': 'YOUR_CONNECTION_PASSWORD',
  }
  

• connection_object: Callable

  connection_object = psycopg2.connect(host,port,database,user,password) #object created from psycopg2.connect()
  

• where: List(dict)

  where = [
      {
          'column_name': 'some_column_name', 
          'value': 'some_value', # can accept str, int, list, or tuple
          'operator': 'some_operator', # can be omitted (accepted operators are =, >, <, >=, <=, IN),
          'conjunction': 'some_conjunction', # can be omitted, used when you need to specify more than one conditions and will link with next index value (accepted conjunctions are AND, OR)
      },
  ],
  

• main_table: Union[dict, str]

  For select query

  main_table = {
      'table': 'some_table_name', 
      'alias': 'some_alias_for_table',
  },
  

  For transaction query

  main_table = 'some_table_name'
  

• join_table: List(dict)

  join_table = [
      {
          'table': 'some_table_name', 
          'alias': 'some_alias_for_table', 
          'join_method': 'join_method', # accepted join methods are (INNER, LEFT, RIGHT, FULL) 
          'on': 'matching_column_on_both_table',
      },
  ]
  

• column_name: List(str)

  column_name = ['some_column_name', 'some_column_name', 'some_column_name',]
  

• column_and_value: dict

  column_and_value = {
      'some_column_name': 'some_value', # for multiple values just provide more key:value pair 
  }
  

• order: dict

  order = {
      'some_column_name': 'ASC', # accepted order values are (ASC, DESC), for multiple order conditions just provide more key:value pair 
  }
  

Usage & Code Samples

Example DB

table: employees

id	first_name	last_name
1	Alex	Garcia
2	Joe	Black
3	John	Doe
4	Barry	Allen
5	Charlie	Cox

table: salaries

employee_id	salary
1	120,000
2	135,000
3	150,000
4	180,000
5	120,000

• SELECT

  • Single Select
    Single select always return a single value from the query, based on fetchone in psycopg2 and returning a dictionary with {column_name: value} of the tables.

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    Parameters:

    connection_string #required
    main_table #required
    where #required
    join_table #optional (if omitted it won't join to any table)
    column_name #optional (if omitted it will select all columns on the provided table)
    

    Code samples:

    # without joining table
    
    from postgres_dynamic import PGDGet
    import asyncio
    
    query_result = PGDGet.get_one(
        connection_string={
            'PG_HOST': 'localhost',
            'PG_PORT': 5432,
            'PG_DATABASE': 'postgres',
            'PG_USER': 'postgres',
            'PG_PASSWORD': 'password'  
        },
        main_table={'table': 'employees'},
        where=[
            {'column_name': 'id', 'value': '1'},
        ],
        column_name=['first_name']
    )
    
    result = asyncio.run(query_result)
    print(result)
    
    # {'first_name': 'Alex'}
    

    # with join table salaries
    
    query_result = PGDGet.get_one(
        connection_string={
            'PG_HOST': 'localhost',
            'PG_PORT': 5432,
            'PG_DATABASE': 'postgres',
            'PG_USER': 'postgres',
            'PG_PASSWORD': 'password'  
        },
        main_table={'table': 'employees', 'alias': 'emp'},
        join_table=[
            {'table': 'salaries', 'alias': 'sal', 'join_method': 'INNER', 'on': 'emp.id = sal.employee_id'}
        ],
        where=[
            {'column_name': 'id', 'value': '1'},
        ],
    )
    
    result = asyncio.run(query_result)
    print(result)
    
    # {'id': '1', 'first_name': 'Alex', 'last_name': 'Garcia', 'employee_id': '1', 'salary': 120000}
    

  • Multi Select Multi select always return a dict with key data, based on fetchall in psycopg2 and returning a list of dictionary with {column_name: value} of the tables. Parameters:

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    connection_string #required
    main_table #required
    where #optional (if omitted no condition will be passed)
    join_table #optional (if omitted it won't join to any table)
    column_name #optional (if omitted it will select all columns on the provided table)
    order #optional (if omitted it won't sort the query)
    limit #optional (if a limit count is given, no more than that many rows will be returned but possibly fewer, if the query itself yields fewer rows)
    offset #optional (it used to skip that many rows before beginning to return rows)
    
    notes:
    - If both OFFSET and LIMIT appear, then OFFSET rows are skipped before starting to count the LIMIT rows that are returned
    - When using LIMIT, it is important to use an ORDER BY clause that constrains the result rows into a unique order. Otherwise you will get an unpredictable subset of the query's rows.
    - For paging, you can specify 0 or 1 for the starting point of the first page
    

    Code samples:

    from postgres_dynamic import PGDGet
    import asyncio
    
    query_result = PGDGet.get_all(
        connection_string={
            'PG_HOST': 'localhost',
            'PG_PORT': 5432,
            'PG_DATABASE': 'postgres',
            'PG_USER': 'postgres',
            'PG_PASSWORD': 'password'  
        },
        main_table={'table': 'employees'},
        limit=3,
        offset=2
    )
    
    result = asyncio.run(query_result)
    print(result)
    
    # {'data': [{'id': '4', 'first_name': 'Barry', 'last_name': 'Allen'}, {'id': '5', 'first_name': 'Charlie', 'last_name': 'Cox'}]}
    

• INSERT

  • Insert Statement
    Insert will not return anyting, and will not saved changes to the database unless you specify commit=True in the parameters.

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    Parameters:

    connection_object #required
    main_table #required
    column_and_value #required
    commit #optional (if omitted, default value will be False which will not saving any changes to database)
    

    Code samples:

    # with auto commit
    
    from postgres_dynamic import PGDTransaction
    import asyncio
    
    connection_object = psycopg2.connect(database='postgres', host='localhost', port=5432, user='postgres', password='password')
    query_result = PGDTransaction.insert(
        connection_object=connection_object,
        main_table='employees',
        column_and_value={'id': 6, 'first_name': 'Harrison', 'last_name': 'Ford'},
        commit=True
    )
    
    result = asyncio.run(query_result)
    print(result)
    
    # None
    # will insert a new employee to the employees table
    

    # without auto commit
    
    connection_object = psycopg2.connect(database='postgres', host='localhost', port=5432, user='postgres', password='password')
    query_result = PGDTransaction.insert(
        connection_object=connection_object,
        main_table='salaries',
        column_and_value={'employee_id': 6, 'salary': 250000},
    )
    
    result = asyncio.run(query_result)
    print(result)
    
    # None
    # will insert a new salary to the salaries table
    
    # save changes to the database
    connection_object.commit()
    
    

• UPDATE

  • Update Statement
    Update will not return anyting, and will not saved changes to the database unless you specify commit=True in the parameters.

    Show more...

    Parameters:

    connection_object #required
    main_table #required
    column_and_value #required
    where #required
    commit #optional (if omitted, default value will be False which will not saving any changes to database)
    

    Code samples:

    # with auto commit
    
    from postgres_dynamic import PGDTransaction
    import asyncio
    
    connection_object = psycopg2.connect(database='postgres', host='localhost', port=5432, user='postgres', password='password')
    query_result = PGDTransaction.update(
        connection_object=connection_object,
        main_table='employees',
        column_and_value={'first_name': 'Tyler', 'last_name': 'Oakley'},
        where=[
            {'column_name': 'id', 'value': '6'},
        ],
        commit=True
    )
    
    result = asyncio.run(query_result)
    print(result)
    
    # None
    # will update employee first_name and last_name with id 6
    

    # without auto commit
    
    connection_object = psycopg2.connect(database='postgres', host='localhost', port=5432, user='postgres', password='password')
    query_result = PGDTransaction.update(
        connection_object=connection_object,
        main_table='salaries',
        column_and_value={'salary': 450000},
        where=[
            {'column_name': 'employee_id', 'value': '6'},
        ],
    )
    
    result = asyncio.run(query_result)
    print(result)
    
    # None
    # will update the salary with employee_id 6
    
    # save changes to the database
    connection_object.commit()
    
    

• DELETE

  • Delete Statement
    Delete will not return anyting, and will not saved changes to the database unless you specify commit=True in the parameters.

    Show more...

    Parameters:

    connection_object #required
    main_table #required
    where #required
    commit #optional (if omitted, default value will be False which will not saving any changes to database)
    

    Code samples:

    # with auto commit
    
    from postgres_dynamic import PGDTransaction
    import asyncio
    
    connection_object = psycopg2.connect(database='postgres', host='localhost', port=5432, user='postgres', password='password')
    query_result = PGDTransaction.delete(
        connection_object=connection_object,
        main_table='salaries',
        where=[
            {'column_name': 'employee_id', 'value': '6'},
        ],
        commit=True
    )
    
    result = asyncio.run(query_result)
    print(result)
    
    # None
    # will delete salary data with employee_id 6
    

    # without auto commit
    
    connection_object = psycopg2.connect(database='postgres', host='localhost', port=5432, user='postgres', password='password')
    query_result = PGDTransaction.delete(
        connection_object=connection_object,
        main_table='employees',
        where=[
            {'column_name': 'id', 'value': '6'},
        ],
    )
    
    result = asyncio.run(query_result)
    print(result)
    
    # None
    # will delete the employee with id 6
    
    # save changes to the database
    connection_object.commit()