Ошибка modulenotfounderror no module named psycopg2

A common error you may encounter when using Python is modulenotfounderror: no module named ‘psycopg2’.

This error occurs when the Python interpreter cannot detect the Psycopg library in your current environment.

You can install Psycopg2 in Python 3 with python3 -m pip install psycopg2-binary.

This tutorial goes through the exact steps to troubleshoot this error for the Windows, Mac and Linux operating systems.

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ModuleNotFoundError: no module named ‘psycopg2’

What is ModuleNotFoundError?

The ModuleNotFoundError occurs when the module you want to use is not present in your Python environment. There are several causes of the modulenotfounderror:

The module’s name is incorrect, in which case you have to check the name of the module you tried to import. Let’s try to import the re module with a double e to see what happens:

import ree

---------------------------------------------------------------------------
ModuleNotFoundError                       Traceback (most recent call last)
1 import ree

ModuleNotFoundError: No module named 'ree'

To solve this error, ensure the module name is correct. Let’s look at the revised code:

import re

print(re.__version__)

2.2.1

You may want to import a local module file, but the module is not in the same directory. Let’s look at an example package with a script and a local module to import. Let’s look at the following steps to perform from your terminal:

mkdir example_package

cd example_package

mkdir folder_1

cd folder_1

vi module.py

Note that we use Vim to create the module.py file in this example. You can use your preferred file editor, such as Emacs or Atom. In module.py, we will import the re module and define a simple function that prints the re version:

import re

def print_re_version():

    print(re.__version__)

Close the module.py, then complete the following commands from your terminal:

cd ../

vi script.py

Inside script.py, we will try to import the module we created.

import module

if __name__ == '__main__':

    mod.print_re_version()

Let’s run python script.py from the terminal to see what happens:

Traceback (most recent call last):
  File "script.py", line 1, in ≺module≻
    import module
ModuleNotFoundError: No module named 'module'

To solve this error, we need to point to the correct path to module.py, which is inside folder_1. Let’s look at the revised code:

import folder_1.module as mod

if __name__ == '__main__':

    mod.print_re_version()

When we run python script.py, we will get the following result:

2.2.1

Lastly, you can encounter the modulenotfounderror when you import a module that is not installed in your Python environment.

What is Psycopg2?

Psycopg2 is a PostgreSQL database adapter for Python. It provides an API to connect to an external database.

The simplest way to install psycopg2 is to use the package manager for Python called pip. The following installation instructions are for the major Python version 3.

Always Use a Virtual Environment to Install Packages

It is always best to install new libraries within a virtual environment. You should not install anything into your global Python interpreter when you develop locally. You may introduce incompatibilities between packages, or you may break your system if you install an incompatible version of a library that your operating system needs. Using a virtual environment helps compartmentalize your projects and their dependencies. Each project will have its environment with everything the code needs to run. Most ImportErrors and ModuleNotFoundErrors occur due to installing a library for one interpreter and trying to use the library with another interpreter. Using a virtual environment avoids this. In Python, you can use virtual environments and conda environments. We will go through how to install psycopg2 with both.

How to Install Psycopg2 on Windows Operating System

First, you need to download and install Python on your PC. Ensure you select the install launcher for all users and Add Python to PATH checkboxes. The latter ensures the interpreter is in the execution path. Pip is automatically on Windows for Python versions 2.7.9+ and 3.4+.

You can check your Python version with the following command:

python3 --version

You can install pip on Windows by downloading the installation package, opening the command line and launching the installer. You can install pip via the CMD prompt by running the following command.

python get-pip.py

You may need to run the command prompt as administrator. Check whether the installation has been successful by typing.

pip --version

Psycopg2 installation on Windows Using pip

To install psycopg2, first create the virtual environment. The environment can be any name, in this we choose “env”:

virtualenv env

You can activate the environment by typing the command:

envScriptsactivate

You will see “env” in parenthesis next to the command line prompt. You can install psycopg2 within the environment by running the following command from the command prompt.

python3 -m pip install psycopg2-binary

We use python -m pip to execute pip using the Python interpreter we specify as Python. Doing this helps avoid ImportError when we try to use a package installed with one version of Python interpreter with a different version. You can use the command which python to determine which Python interpreter you are using.

How to Install Psycopg2 on Mac Operating System using pip

Open a terminal by pressing command (⌘) + Space Bar to open the Spotlight search. Type in terminal and press enter. To get pip, first ensure you have installed Python3:

python3 --version

Python 3.8.8

Download pip by running the following curl command:

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py

The curl command allows you to specify a direct download link. Using the -o option sets the name of the downloaded file.

Install pip by running:

python3 get-pip.py

To install psycopg2, first create the virtual environment:

python3 -m venv env

Then activate the environment using:

source env/bin/activate 

You will see “env” in parenthesis next to the command line prompt. You can install psycopg2 within the environment by running the following command from the command prompt.

python3 -m pip install psycopg2-binary

How to Install Psycopg2 on Linux Operating Systems

All major Linux distributions have Python installed by default. However, you will need to install pip. You can install pip from the terminal, but the installation instructions depend on the Linux distribution you are using. You will need root privileges to install pip. Open a terminal and use the commands relevant to your Linux distribution to install pip.

Installing pip for Ubuntu, Debian, and Linux Mint

sudo apt install python-pip3

Installing pip for CentOS 8 (and newer), Fedora, and Red Hat

sudo dnf install python-pip3

Installing pip for CentOS 6 and 7, and older versions of Red Hat

sudo yum install epel-release

sudo yum install python-pip3

Installing pip for Arch Linux and Manjaro

sudo pacman -S python-pip

Installing pip for OpenSUSE

sudo zypper python3-pip

Psycopg2 installation on Linux with Pip

To install psycopg2, first create the virtual environment:

python3 -m venv env

Then activate the environment using:

source env/bin/activate 

You will see “env” in parenthesis next to the command line prompt. You can install psycopg2 within the environment by running the following command from the command prompt.

Once you have activated your virtual environment, you can install psycopg2 using:

python3 -m pip install psycopg2-binary

Installing Psycopg2 Using Anaconda

Anaconda is a distribution of Python and R for scientific computing and data science. You can install Anaconda by going to the installation instructions. Once you have installed Anaconda, you can create a virtual environment and install psycopg2.

To create a conda environment you can use the following command:

conda create -n psycopg2 python=3.8

You can specify a different Python 3 version if you like. Ideally, choose the latest version of Python. Next, you will activate the project container. You will see “psycopg2” in parentheses next to the command line prompt.

source activate psycopg2

Now you’re ready to install psycopg2 using conda.

Once you have activated your conda environment, you can install psycopg2 using the following command:

conda install -c anaconda psycopg2

Check Psycopg2 Version

Once you have successfully installed psycopg2, you can check its version. If you used pip to install psycopg2, you can use pip show from your terminal.

python3 -m pip show psycopg2-binary

Name: psycopg2-binary
Version: 2.9.3
Summary: psycopg2 - Python-PostgreSQL Database Adapter

Second, within your python program, you can import psycopg2 and then reference the __version__ attribute:

import psycopg2
print(psycopg2.__version__)

2.9.3

If you used conda to install psycopg2, you could check the version using the following command:

conda list -f psycopg2

# Name                    Version                   Build  Channel
psycopg2                  2.8.5            py38hddc9c9b_0    anaconda

Summary

Congratulations on reading to the end of this tutorial. The modulenotfounderror occurs if you misspell the module name, incorrectly point to the module path or do not have the module installed in your Python environment. If you do not have the module installed in your Python environment, you can use pip to install the package. However, you must ensure you have pip installed on your system. You can also install Anaconda on your system and use the conda install command to install psycopg2.

Go to the online courses page on Python to learn more about Python for data science and machine learning.

For further reading on missing modules in Python, go to the article:

• How to Solve Python ModuleNotFoundError: no module named ‘urllib2’.
• How to Solve ModuleNotFoundError: no module named ‘plotly’.
• How to Solve Python ModuleNotFoundError: no module named ‘boto3’.

Have fun and happy researching!

Many developers face the issue of the No module named ‘psycopg2’ when they try to take their project to the production level. With the help of this article, we will understand the cause of the error and the possible solutions to avoid them. Let’s dive in.

What is ‘psycopg2’?

‘psycopg2’ is the most popular database adapter dealing in PostgreSQL. Its core is to completely implement the Python DB API 2.0 specification and the thread-safety. That means it can allow several threads to share a standard connection. It can easily handle concurrent insertion and deletion in an application. It can create or destroy lots of connections simultaneously.

Architechture behind ‘psycopg2’

‘psycopg2’ uses a libpq wrapper, which implements the C programming language interface. It consists of a set of library functions that allow client programs to receive the results of the queries passed to the PostgreSQL backend server.

Cause behind the error: No module named ‘psycopg2’

To execute the program smoothly, some pre-requisites should be met. Failing to meet these requirements will trigger import errors during the compilation.

Pre-requisites are :

1. Python Version
   • 3.6 to 3.9
2. PostgreSQL server versions
   • 7.4 to 13
3. PostgreSQL client library version
   • from 9.1
4. C compiler
5. Package such as python-dev or python3-dev to install python header files.
6. libpq-dev package containing libpq header files.
7. pg-config file should be present in the PATH file. It compiles ‘psycopg2‘

If the system does not meet the above requirements, the ‘psycopg2’ module will not be installed, leading to no modules name ‘psycopg2’ error. This error is often viewed by programmers who don’t have a C compiler in their system. As the binaries fail to install, the module will not work.

Resolving the issue: No module named ‘psycopg2’

To resolve the issue, we must satisfy all the pre-requisites laid by the ‘psycopg2’ to meet its build requirements. However, pyscopg2 also provides us with a binary package with its versions of C libraries, libpq, and libssl, which will be used regardless of other libraries available to the client.

Perform these commands to resolve the issue:

pip uninstall psycopg2
pip install psycopg2-binary

Running the above commands will solve the problem, but the installation may fail in a few cases due to a non-supportive environment. Follow these steps to install the precompiled library –

1. Go to the Precompiled Library Packages list.
2. Then download the wheel file (.whl) for the psycopg module.
3. Then use the command pip install <file>.whl to install the library using downloaded wheel file.

Using the above steps will guarantee installing psycopg2 on your computer.

Working On Incorrect Virtual Enviornment?

Many “No module named psycopg2” errors occur due to working on incorrect virtual environments and installing the ‘psycopg2’ on a different environment. Suppose you have two versions of python3 installed, and how will you install ‘psycopg2’ to a specific python?

Use the following command to call your python and install the package in your respective environment –

python3 -m pip install psycopg2

This will ensure that you install the psycopg2 module in the working environment. Hopefully, this resolves the issue. Moreover, if you face the C Compiler issues in this method, use the precompiled method as mentioned last way.

Recommended Reading | [Solved] No Module Named Numpy in Python

Resolving No module named ‘psycopg2’ in AWS EC2 lambda/ Linux OS

However, one cannot rely on binary packages if they are using them in production, and we should build the ‘psycopg2’ from the source. Because upgrading the system libraries will not upgrade the libraries used by ‘psycopg2'. Hence, there might be a dependencies error.

One can perform these commands to solve the problem

sudo apt install gcc g++ build-essential
sudo apt install python3-dev
sudo apt install libpq-dev
python -m pip install psycopg2

How to solve the No module named ‘psycopg2’ Error in Conda/Anaconda?

Conda or Anaconda has its virtual environment. So to work ‘psycopg2’, you have to install psycopg2 on Conda Environment. Use conda install psycopg2 to install psycopg2.

How to solve the No module named ‘psycopg2’ Error in Jupyter?

In most cases, Jupyter Notebook works in the anaconda environment. Use the conda install psycopg2 command to install the package in Jupyter. If it’s not working on Anaconda Environment, you have to find the location of the working environment and install the package there.

Conclusion

So, in this way, one can resolve the import error related to the PostgreSQL connection. A quick tip is to keep in mind the requisites we should follow before executing any program. We can permanently activate a python virtual window and maintain that virtual window according to the project’s needs. Now it’s your time to leverage the DB connection and create fantastic projects with ‘psycopg2’ and PostgreSQL.

Bon Codage!

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Django is a powerful and feature-rich framework that allows you to build web applications with database capabilities. However, when working with Django and database management systems such as PostgreSQL, these two technologies are different as they are made using different languages.

Thus, you must have an intermediary that allows the two technologies to communicate and interact. An example of an intermediary is the psycopg2 database driver that enables you to perform database operations on PostgreSQL using Python.

But even with the best tool, you can sometimes have some frustrating moments when dealing with database connections. Whether you have a misconfigured DATABASE setting, syntax error, or mistyped code, these errors can be pretty disappointing to troubleshoot and fix.

One common exception you may get when working with PostgreSQL and Django is the ModuleNotFound Exception. The exception is just a simple way that Django tells you that it cannot find the file referenced in the import statement.

Thus, the psycopg2 binary cannot be located because either it has not been installed in your Python virtual environment or you have a misconfigured setting.

Let’s look in detail at the reasons that would lead you down the path of connection errors with the psycopg2 module.

Reasons why psycopg2 is not working with Django

There are a couple of reasons why the psycopg2 module may not be working in your Django project:

1. The psycopg2 binary is not installed in your virtual environment.
2. For Python versions < 3.4, you have not installed psycopg2-binary binary in your Python virtual environment.
3. You have not configured Django to use the psycopg2 module in your database ENGINE setting.
4. You have a misconfigured database connection that could arise from incorrect or mistyped database engine settings.

Here is a detailed explanation as to why you may have database connection details when working with PostgreSQL and Django and the approach to fix the error.

The psycopg2 module is not installed in your Python virtual environment

When working with Python Django and PostgreSQL databases, a database driver is needed for the two technologies to communicate. Thus, you must install the psycopg2 database driver in your Python virtual environment you have installed Django.

The most common contributor to the exception “django.core.exceptions.ImproperlyConfigured: Error loading psycopg2 module: No module named ‘psycopg2’” in Django arises from not installing the psycopg2 module.

Thus, to fix the ‘No module named psycopg2’ error, you must install psycopg2 in your virtual environment.

Here are the steps to fix the No module named ‘psycopg2‘ in Django by installing the psycopg2 module.

Step 1: Activate the virtual environment you have installed Django

Open the Terminal window and type the following

source path_to_env/bin/activate 

# example
source ~/.virtualenvs/DjangoBlogEnv/bin/activate  

Step 2: Install the psycopg2 module using pip

After activating the virtual environment, type the following command to install the psycopg2 module.

pip install psycopg2

Step 3: Add ‘django.db.backends.postgresql’ as the default ENGINE

After installing psycopg2, you must configure Django to use PostgreSQL as the default database.

Open the settings.py file and locate the DATABASES dictionary.

Add ‘ENGINE’: ‘django.db.backends.postgresql’, line.

Step 4: Run your migrations

You should run your migrations now that you have installed psycopg2 and configured Django to use the PostgreSQL database engine.

python manage.py migrate

Try rerunning your Django development server; you should not get the ModuleNotFound exception again.

python manage.py runserver

The psycopg2-binary module is not installed for Python versions lower than 3.4

If you use a Python version lower than 3.4, installing psycopg2 will not work for your Django project due to concurrency problems with binary packages. Instead, you should install psycopg2-binary to use PostgreSQL with Python.

Here are the steps to configure the Django project using a Python version lower than 3.4 to use PostgreSQL.

Step 1: Activate the virtual environment you have installed Django

Open the Terminal window and type the following

source path_to_env/bin/activate 

# example
source DjangoBlogEnv/bin/activate  

Step 2: Install the psycopg2-binary module using pip

After activating the virtual environment, type the following command to install the psycopg2-binary module.

pip install psycopg2-binary

Step 3: Add ‘django.db.backends.postgresql’ as the default ENGINE

After installing psycopg2, you must configure Django to use PostgreSQL as the default database.

Open the settings.py file and locate the DATABASES dictionary.

Add ‘ENGINE’: ‘django.db.backends.postgresql’, line.

Step 4: Run your migrations

You should run your migrations now that you have installed psycopg2 and configured Django to use the PostgreSQL database engine.

python manage.py migrate

Try rerunning your Django development server; you should not get the ModuleNotFound exception again.

python manage.py runserver

Not configuring Django to use psycopg2 module in your database connection settings

If you have not configured Django to use the psycopg2 module, you will likely get an error when connecting Django and PostgreSQL. Another reason you may have a ‘ModuleNotFound: no module named psycopg2’ error in Django is that you have a mistyped database connection settings.

For example, having a mistyped ENGINE value will lead to a ModuleNotFound error.

Check that you have configured your Django DATABASES dictionary well.

Use the following code for reference:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'DATABASE_NAME',
        'USER': 'DB_USER',
        'PASSWORD': 'DB_PASSWORD',
        'HOST': 'localhost or AWS RDS URL',
        'PORT': '5432',
    }
}

The default port for connecting the PostgreSQL database to Django is 5432. Thus, in your Django settings, do not forget to specify the PORT. Besides, the PORT value should be a string.

However, you are at liberty to use another port number provided other services on your Linux system do not use it. When using a different port for your PostgreSQL database, you need to specify that particular port number in the PORT field.

How to fix ModuleNotFound: no module named psycopg2

There are a few reasons why your PostgreSQL connection with Django is not working while using the psycopg2 module. To fix the ModuleNotFound: no module named psycopg2 in Django, check that you have the following.

1. Installed psycopg2 or psycopg2-binary installed in your Python virtual environment. You can install the psycopg2 binary by activating your Django project virtual environment and executing 'pip install psycopg2' or 'pip install psycopg2-binary'
2. Configured Django database connection details correctly. A misconfiguration in your DATABASES setting in your Django settings is a common cause for the ModuleNotFound exception. Ensure you have correctly typed the database ENGINE value. Check that you have the following line in your DATABASES settings variable: 'ENGINE': 'django.db.backends.postgresql',
3. You have activated the correct virtual environment that has the psycopg2 installed. When using a virtual environment, make sure you have activated it by running source path_to_env/bin/activate command before your try to use psycopg2.
4. Installed all the dependencies, including the postgresql-libs, on your Linux machine.

Related Questions

How to install psycopg2 in VS Code?

When using Visual Studio Code, you can install psycopg2 easily by following these steps:

Step 1: Open VS code and activate the virtual environment for your Django project

Open the terminal window in visual studio code by pressing CTRL + `

Type the following command to activate the virtual environment:

source /path_to_your_env_folder/bin/activate

Step 2: Install psycopg2 using pip

After activating the virtual environment, type the following command to install psycopg2 or psycopg2-binary module using pip.

pip install psycopg2

# or

pip install psycopg2-binary

After you have successfully installed the psycopg2 module, you should be able to connect PostgreSQL to your Django project.

How to install psycopg2 with pipenv

Follow these steps to install psycopg2 using pipenv:

Step 1: Navigate into your project root directory

Using the Terminal, navigate into the root directory of your Django project using the cd command.

cd /path_to_project_directory/

Step 2: Activate pipenv environment using pipenv shell command

pipenv shell

Step 3: Install psycopg2 using pipenv

Install the psycopg2 module using pipenv by running the following command:

pipenv install psycopg2

If you have Python version 3.4 and lower, use the following command:

pipenv install psycopg2-binary

After a successful installation, you may configure your Django or Python project to use the PostgreSQL database.

How do I know if psycopg2 is installed?

Python provides several ways to check if psycopg2 is installed in your virtual environment. You can use either of the following ways to ensure you have installed psycopg2 correctly:

Check the list of installed modules using Python

Inside your Python project, create a new file called check.py and paste the following code:

from importlib import util
if util.find_spec("psycopg2"):
    print("psycopg2 is installed")
else:
    print("psycopg2 is not installed")

Activate the virtual environment you want to check if psycopg2 is installed.

source /path_to_env/bin/activate

Run the Python file by executing the following command:

python check.py

You should get a result indicating whether psycopg2 is installed.

Check your requirements.txt file or run pip freeze to see whether psycopg2 is installed

If you have a requirements.txt file, you can check whether psycopg2 or psycopg2-binary is listed.

Besides, you can run pip freeze command to check psycopg2 installation. You should see psycopg2 listed if it is installed.

Otherwise, you will not find it. Because of that, you have to install psycopg2 by running pip install psycopg2

Can psycopg2 connect to MySQL?

You cannot use psycopg2 as a database adapter for MySQL. Psycopg2 is a database driver designed for PostgreSQL database management system and is incompatible with MySQL.

If you wish to use MySQL database in your Django project, you need to install a different database driver such as mysql-client. The mysql-client adapter is designed to connect to the MySQL database when using Python.

To use the MySQL database with Django, you need to modify your Django project settings to interact with the MySQL backend.

First, install mysql-client by executing the following command:

pip install mysql-client

Secondly, open your project settings.py file, and inside the DATABASES variable, replace the ENGINE dictionary key to look like this:

DATABASES = {
    'default': {
        # replaced line
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'DB_NAME',
        'USER': 'DB_USER',
        'PASSWORD': 'DB_USER_PASSWORD',
        'HOST':'localhost',
        'PORT':'3306',
    }
}