Eve: Building RESTful APIs with MongoDB and Flask Transcripts
Chapter: Setup and tools
Lecture: Installing Eve and its dependencies
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Installing Eve is a simple task.
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As with basically every other Python tool,
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you really want to install it into a virtual environment.
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A virtual environment is a Python environment
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where the Python interpreter, libraries and scripts installed into it
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are isolated from those installed in other virtual environments
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and any libraries installed in a system Python,
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like the one which is installed as part of your operating system.
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So let's install Eve.
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As you can see, I'm using a Mac here,
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if you are on Windows, don't worry,
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everything you see me doing during this course will also work on Windows
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just make sure that you are using backslashes
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whereas I'm typing forward slashes in the file paths,
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folder names, stuff like that.
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The first thing we want to do is make sure
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that Python is actually installed on our system and ready to work.
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So let's ask which Python 3, there it is, so we can use it.
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If you wanted to use Python 2,
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of course, we just have to go with Python.
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We now want to create our vital environment
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and within this virtual environment,
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we will install Eve and all of its dependencies,
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so Eve will be isolated from other Python installations in our system.
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When it comes to virtual environments in Python
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we are left with two options really,
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one is called virtual env, you probably know about it already
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because it's been around since forever,
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it is very nice because it works equally well on Python 2 and Python 3,
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so if you are working on Python 2, you probably want to use it.
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You actually have to install it because it doesn't come with Python
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but since we are working on Python 3,
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we want to use the new method which comes built in with the Python itself
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so we are going with Python 3 - m venv
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and then it wants a path, virtual envs/eve-course,
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so let's review this command here.
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Python 3 is, of course, the interpreter,
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- m is an option which is basically instructing Python
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to execute the following module here as a script and then we have a path,
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if the path doesn't exist on your system, it will be created for you.
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As you can see, I'm using a root folder for all my virtual environments
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and then I'm building an Eve course folder within the root folder.
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Let's execute it— bam,
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now let's take a look at our system,
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as you can see, I have a new folder here virtual env,
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and if I look at it there is my Eve course within it.
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If we inspect the Eve course, we see that the number of folders on the file
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we don't really care about what is being stored within this folder,
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we just need to know that this is where all of our packages will be installed
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and where the activation and the activation scripts
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for our virtual environment are also stored.
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How do we activate this virtual environment actually?
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Well, I just use the source command
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and then I go and use the activate script
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as you can see, the prompt has changed
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and it is telling me that now we are inside our virtual environment
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and since we are inside a virtual environment
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and every single virtual environment activated with Python
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comes with the installation tools
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we can already use pip
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and ask for what's installed in our environment right now,
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and of course, there is nothing because we just created this environment.
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Now I can go and finally install Eve with pip install eve.
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When I hit return here, it will go online, look up for Eve
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and then install Eve itself and all of its dependencies.
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There it goes.
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As you can see it's collecting all the info
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and then it is running all the setups,
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scrapes for each of the dependencies,
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and finally we get a very nice message here
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which is telling us all the dependencies
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with their versions which have been installed.
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Now, if I try pip freeze again
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I see that I have all of my dependencies ready to work
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and in fact, if I run Python, I get Python 3.6.
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I can for example import Eve— it works.
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And how do I deactivate my virtual environment?
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Well, it is very easy, I just need to use the deactivate command.
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As you can see, the prompt has changed back again
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to no virtual environment name
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and in fact, if I try to use pip here, it doesn't even work
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because it's not there, it only comes with virtual environment
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or I have to install it on my system Python,
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I can always go back to my
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virtual environment and again, ready to work.
