Python DB 连接 PostgreSQL 错误（模块）

Question

目前，我正在使用Python 学习数据库。

我正在尝试在 OOP 范式下建立 postgresql 数据库连接。 我按照article 中的所有步骤操作，但运行代码时出现错误。

所有代码都是一样的，我只是用我的数据库设置修改了database.ini 文件。

**database.ini代码：

[postgresql]
host = localhost
port = 5432
database = dvdrental
user = postgres
password = 1234

**config.py代码：

# import libraries
from configparser import ConfigParser
import configparser
from pathlib import Path

def get_project_root() -> Path:
    ''' Return project root folder '''
    return Path(__file__).parents[1]

def config(config_db):
    
    section = 'postgresql'
    
    config_file_path = 'config/' + config_db

    if (len(config_file_path) > 0 and len(section) > 0):
        # create an instance of ConfigParser class
        config_parser = ConfigParser()

        # read the configuration file
        config_parser.read(config_file_path)

        # if the configuration file contains the provided section name
        if(config_parser.has_section(section=section)):
            # read options of the sections
            config_params = config_parser.items(section=section)

            # convert the list object to a python dictionary object
            # define an empty dict
            db_conn_dict = {}

            # loop in the list
            for config_param in config_params:
                # get options key and value
                key = config_params[0]
                value = config_params[1]

                # add the key value pair in the dictionary object
                db_conn_dict[key] = value
            
            # get connection object use above dictionary object
            return db_conn_dict

**db_conn.py代码：

# import libraries
import pandas as pd 
import psycopg2
from config.config import config

# take in a PostgreSQL table and outputs a pandas dataframe
def load_db_table(config_db, query):
    params = config(config_db)
    engine = psycopg2.connect(**params)
    data = pd.read_sql(query, con = engine)
    return data

**main.py代码：

# import library
from src.data.db_conn import load_db_table
from config.config import get_project_root

# project root
PROJECT_ROOT = get_project_root()

# read database
df = load_db_table(config_db = 'database.ini', query = 'SELECT * FROM actor LIMIT 5')

print(df)

问题是，当我运行程序时，我得到了error：

TypeError: connect() keywords must be strings
PS D:\ASUS\MY CODES PYTHON\Iochordxsyy\db_connection> python main.py
Traceback (most recent call last):
  File "main.py", line 9, in <module>
    df = load_db_table(config_db = 'database.ini', query = 'SELECT * FROM actor LIMIT 5')
  File "D:\ASUS\MY CODES PYTHON\Iochordxsyy\db_connection\src\data\db_conn.py", line 9, in load_db_table
    engine = psycopg2.connect(**params)
TypeError: connect() keywords must be strings

这是我debugged我的代码时的消息：

Exception has occurred: TypeError
connect() argument after ** must be a mapping, not NoneType
  File "D:\ASUS\MY CODES PYTHON\Iochordxsyy\db_connection\src\data\db_conn.py", line 9, in load_db_table
    engine = psycopg2.connect(**params)
  File "D:\ASUS\MY CODES PYTHON\Iochordxsyy\db_connection\main.py", line 9, in <module>
    df = load_db_table(config_db = 'database.ini', query = 'SELECT * FROM actor LIMIT 5')

我检查了所有代码都与文章相同，但我不知道为什么仍然会出现错误。你有什么想法吗？

如果您有任何想法/解决方案，我们将不胜感激。

谢谢。

信用： 感谢上述文章的作者。

Answer 1

对齐this:config.py的缩进，如下图。

if (len(config_file_path) > 0 and len(section) > 0):
    # create an instance of ConfigParser class
    config_parser = ConfigParser()

    # read the configuration file
    config_parser.read(config_file_path)

    # if the configuration file contains the provided section name
    if(config_parser.has_section(section=section)):
        # read options of the sections
        config_params = config_parser.items(section=section)

        # convert the list object to a python dictionary object
        # define an empty dict
        db_conn_dict = {}

        # loop in the list
        for config_param in config_params:
            # get options key and value
            key = config_params[0]
            value = config_params[1]

            # add the key value pair in the dictionary object
            db_conn_dict[key] = value
        
        # get connection object use above dictionary object
return db_conn_dict

Answer 2

[已解决]

大家好，我得到了答案。 config.ini 文件中有错误脚本。 I change the script from "config_params[]" to "config_param[]"

** 正确脚本：

...
key = config_param[0]
value = config_param[1]
...

感谢所有的cmets。

Answer 3

我认为 database.ini 中的“username”关键字必须是“user”。

** database.ini 代码：

[postgresql]
host = localhost
port = 5432
database = dvdrental
user = postgres
password = 1234