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In this video we'll install Sequelize and set our project up with it.
Getting Started
If you're following along, be sure to install the application's dependencies (listed in the provided package.json file) by running the following command:
npm install
After the application's dependencies have finished installing, run the following command to fix any security vulnerabilities that can be automatically fixed:
npm audit fix
Note: Some security vulnerabilities need to be manually reviewed and updated to be fixed. For the purposes of this workshop, it's okay to hold off on updating these kinds of vulnerabilities.
Sequelize Installation
npm install sequelize
npm install sqlite3
npm install sequelize-cli
Note: As of npm 5.0, the npm install command will save dependencies by default, so the --save option isn't necessary to include.
String Based Operators Warning
If you install Sequelize 4.0 (or later), you'll receive the following warning when starting the application:
String based operators are now deprecated. Please use Symbol based operators for better security, read more at http://docs.sequelizejs.com/manual/tutorial/querying.html#operators
Updating your Sequelize configuration file (/config/config.json) to the following will disable string based operators and prevent the warning from displaying:
{
"development": {
"dialect": "sqlite",
"storage": "development.db",
"operatorsAliases": false
},
"test": {
"dialect": "sqlite",
"storage": "test.db",
"operatorsAliases": false
},
"production": {
"dialect": "sqlite",
"storage": "production.db",
"operatorsAliases": false
}
}
For more information about this issue, see http://docs.sequelizejs.com/manual/tutorial/querying.html#operators-security.
Commands
npm 5.2 introduced the
npxutility, which can be used in place ofnode_modules/.bin/when interacting with tools like the Sequelize CLI.
To obtain a list of commands:
npx sequelize help
To initialize the project:
npx sequelize init
To see how the model:create command works:
npx sequelize model:create --help
To generate a model, use the following command pattern:
npx sequelize model:create --name ModelName --attributes attribute1:data_type,attribute2:data_type
To generate the "Article" model shown in the video, use the command:
npx sequelize model:create --name Article --attributes title:string,author:string,body:text
Running this command with version 4.0 of the Sequelize CLI generates the following model:
'use strict';
module.exports = (sequelize, DataTypes) => {
const Article = sequelize.define('Article', {
title: DataTypes.STRING,
author: DataTypes.STRING,
body: DataTypes.TEXT
}, {});
Article.associate = function(models) {
// associations can be defined here
};
return Article;
};
Sequelize Methods Used
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We'll be using the Sequelize ORM
in our project.
0:00
It's one of the most popular ORMs for
Node.js.
0:04
If you go to Getting Started,
0:08
it should show you what NPM
packages you need to install.
0:10
How to set up the database connection and
how to set up a model.
0:14
Then, theres the most common gotchas that
you'll encounter when using promises.
0:21
We're going to install sequelize and
sequellite three.
0:27
Since we're using a sequellite
databases in our example app.
0:32
A lot of code in this getting
started document is good to use
0:56
as a reference when
building your own models.
0:59
But when you're building
any sizable application,
1:03
writing all of this boilerplate
code by hand can get tiresome.
1:06
And you could easily make a mistake.
1:10
Many development tools have what you call,
a CLI or command line interface.
1:17
That is a special piece of software that
is used to aid in the development process.
1:23
It generates a lot of boilerplate or
1:28
standard code that you'd
write all the time.
1:30
Let's get that installed.
1:33
You can run the Sequelize CLI by typing,
1:48
node _modules/.bin/sequelize.
1:52
Any decenct CLI will have a help command.
1:56
If you ever to get stuck you can
always run the CLI with the help flag.
2:08
The two commands we'll be using are init,
2:16
which initializes the project and
model create, to create a model.
2:20
We'll use the help command to
see how we use it shortly.
2:30
First, let's initialize our
project with the init command.
2:34
This will initialize all
the configuration code,
2:43
folders and helpers that we need for
our application.
2:46
It sets up four folders,
Config, Migrations, models.
2:55
And seeders.
3:04
Let's look first at the config folder
3:07
where we add code to configure
out database connections.
3:10
For development testing and
production environments.
3:13
In the newly created config folder,
there is a JSON config file.
3:17
This contains three configurations for
3:21
the three main environments
you need in any application.
3:24
Your development environment
when your programming your app.
3:29
Testing, for running automated
tests to make sure your code
3:33
interacts correctly with the database.
3:37
And production, for the live site, filled
with real data your application needs.
3:39
This is configured with boilerplate
credentials for a MySQL Database but
3:46
we want to use other relational databases.
3:51
In this case, we're using SQLite.
3:54
Remember, on the getting
started documentation,
3:56
there was a section saying how
to set up a database connection.
4:00
All the options here can be
specified in the config file.
4:04
Ideally in development,
4:09
you want to use the same database
you would use in production.
4:10
But you could use a SQLite in
a development and testing environment and
4:13
PostgreSQL for production.
4:18
For example, you could use SQLite so
4:20
that you don't need to install
a heavier database on your laptop.
4:22
And PostgreSQL for
a powerful Linux server in production.
4:26
See how you can specify a dialect or
the specific version of SQL we're using.
4:30
We can use that for our environments.
4:38
Since we're using SQL light,
4:52
a file based database that doesn't
require credentials or a host.
4:54
We can use the storage
key with the files path.
4:58
The sequelize SLI created
a few directories,
5:39
including the config
directory we just looked at.
5:42
Another important folder
is the models folder,
5:48
which holds the code that maps
JavaScript objects to database tables.
5:51
In the models folder,
5:56
there's an index Index JS file, this
file will import any models we define.
5:57
For example,
6:02
we'll be creating an article model to
map properties of a JavaScript object.
6:03
That we can use in our
programming code to columns
6:08
in a database table named articles.
6:12
The index file also exposes the sequalized
package whenever we import models
6:15
into our application code.
6:20
This means, whenever we import models,
we'll have this sequalized package.
6:22
With all of the methods and
functionality to use.
6:27
Let's generate our first model,
an article.
6:35
To see how we can use the model:create
command, we can run the sequelize command.
6:39
And then,
type in the command help:model:create.
6:49
Here's an example of how to use it.
6:58
You can specify the model name, which
matches a table name in the database.
7:00
In this example, sequelize will look for
the information in the users table.
7:05
An important distinction,
is that the model name is singular and
7:10
that the table name is plural and
lowercase.
7:14
This is a convention sequelize uses,
it's automatic and
7:18
you don't have to worry about it.
7:22
Then, the mode attributes our properties,
which match the column names in the table.
7:24
Each attribute has the data type after it.
7:30
In other words, in this example, this
code creates a model for the users table.
7:33
With three columns, first name,
last name, and bio.
7:38
Let's create our article generating
command using this example.
7:44
We need to start with
the sequelize command model:create.
7:49
Then the name of our model.
8:00
Then we can specify the attributes.
8:05
Which is a title, which is a string.
8:12
Author.
8:20
Which is a string.
8:23
And body, which is a body of text or
a large string.
8:27
When we hit return,
the model code is generated and
8:32
a new JavaScript file is created.
8:36
Let's take a peek inside
the article doc j.s file.
8:42
You can see the article defined
with the title, author, and body.
8:49
These attributes are the column names
in the table storing all articles.
8:57
This article model is exported.
9:03
And this is what is included within
the model code in the index JS file.
9:05
Finally, we want the database to be
updated with the models we've created.
9:15
In other words,
we want the articles table to be created.
9:20
Once we've defined the model in
JavaScript, we need to sync those changes.
9:25
We can do this automatically,
every time the service starts.
9:30
Going back to the Sequelize home page,
9:36
we can see that there's a sync
method on Sequelize object.
9:38
The sync method will automatically
create or update any database tables.
9:41
We call this method every
time the service starts.
9:47
So an ideal place to do this,
would be when the server spins up.
9:51
If you go to the bin slash www file and
9:55
just rename it to doc js, so
we can edit it in workspaces.
9:58
This is the file that the express
site generator creates for
10:08
express applications.
10:11
We can look down where
the service starts listening.
10:14
We could use the sync method first and
once the database of dates are complete,
10:19
we can start listening to the web server.
10:24
And before I forget,
10:45
let's remember to require
the sequelize at the top of the file.
10:47
Let's rename this back.
11:13
When we went nmp start now,
you should see the development.db
11:24
file created at the root
of the application folder.
11:28
Now that we have the database code set up,
11:35
we can now focus on the important
parts of our application.
11:37
We currently have no data in the database.
11:41
In the next video, we'll work
on the routes for data creation.
11:44
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