Project Summary

In this project, we are going to make our first full CRUD back-end that uses a database.

Step 1

Summary

In this step, we are going to create a bare-bones server.

Instructions

• Run npm init -y.
• Use npm to install express, dotenv and massive.
• Create a .env file.
  • Define a variable inside named SERVER_PORT and set it to 3000.
• Create a .gitignore to ignore the node_modules folder and the .env file.
• Create an index.js file.
• Require all the packages that we installed.
• Get your server listening on port 3000.

Detailed Instructions

Let's begin by opening a new terminal window and cd into the project. Let's create a package.json file by running npm init -y. Using the -y flag, we'll get a package.json file with all the default values. Now that we have a package.json file, we can use npm install to install packages to it. Run npm install express massive dotenv to get all the packages we'll need for this project.

After that is finished, we can see it created a node_modules folder. We never want to include this folder on GitHub, so let's create a .gitignore that will ignore node_modules. Create a file and name it .env. This file also needs to be included in the .gitignore. Inside this file we will set up our port. Create a variable with the name SERVER_PORT and set it equal to 3000.

SERVER_PORT = 3000

After that, we're ready to start creating our server. Create an index.js file and require all the packages we install at the top.

require('dotenv').config()
const express = require('express');
const massive = require('massive');

Now that our index.js file has access to all our packages, let's create a basic server. We'll begin by saving express() to a variable called app.

const app = express();

Next we will destructure the SERVER_PORT variable off of process.env.

const { SERVER_PORT } = process.env;

Then, we'll want to use our express.json middleware.

app.use(express.json());

Finally, we'll want to tell the server to listen on port 3000 using the variable from our .env and use a console.log to tell us when it is listening.

app.listen(SERVER_PORT, () => {
  console.log(`Server listening on port ${SERVER_PORT}.`);
});

Solution

.gitignore

node_modules
.env

index.js

require("dotenv").config();
const express = require("express");
const massive = require("massive");

const app = express();

const { SERVER_PORT } = process.env;

app.use(express.json());

app.listen(SERVER_PORT, () => {
  console.log(`Server listening on port ${SERVER_PORT}.`);
});

Step 2

Summary

In this step, we are going to add massive to the server so we can connect to a database.

Instructions

• Open the .env file and create a variable called CONNECTION_STRING that equals the URI connection string from your Heroku database.
  • Make sure to add ?ssl=true at end of your connection string.
• Use massive and the CONNECTION_STRING to establish a connection.
• In the .then callback from massive, set db on app to equal the database instance.
• Make sure to add a .catch() with a callback function.
• In the callback of the .catch, console.log the error that would be received if the request was rejected.

Detailed Instructions

Now that we have a basic node server ready to go, let's modify it to connect to a postgres database. Open the .env file and create a variable called CONNECTION_STRING that equals the URI connection string from your Heroku database, it should look something like this postgres://username:password@host/dbname?ssl=true.

Then destructure CONNECTION_STRING off of process.env in the server. Using the CONNECTION_STRING, we can invoke massive and pass it in as the first argument. This will return a promise.

CONNECTION_STRING=postgres://username:password@host/dbname?ssl=true

const { SERVER_PORT, CONNECTION_STRING } = process.env;

massive(CONNECTION_STRING);

We'll want to execute some logic when the promise is fulfilled, so let's chain a .then to it. Be sure to capture the database instance in the first parameter.

massive(CONNECTION_STRING).then(dbInstance => {});

Now that we have the dbInstance, we can set it onto app. Let's have our function return app.set('db', dbInstance).

massive(CONNECTION_STRING)
  .then(dbInstance => {
    app.set('db', dbInstance);
  });

Finally, we need to add a .catch so that we can console.log any error we might receive. Do so by chaining .catch after the .then. The .catch takes a callback function. Name the callback function parameter err. If .catch is invoked, err will be the error that was received. Add a console.log to log the error.

massive(CONNECTION_STRING)
  .then(dbInstance => {
    app.set("db", dbInstance);
  })
  .catch(err => console.log(err));

Solution

index.js

require("dotenv").config();
const express = require("express");
const massive = require("massive");

const app = express();

const { SERVER_PORT, CONNECTION_STRING } = process.env;

massive(CONNECTION_STRING)
  .then(dbInstance => {
    app.set("db", dbInstance);
  })
  .catch(err => console.log(err));

app.use(express.json());

app.listen(SERVER_PORT, () => {
  console.log(`Server listening on port ${SERVER_PORT}.`);
});

Step 3

Summary

In this step, we are going to create our table and the .sql files we'll need to preform operations on our data. The schema for our table will look like:

• product_id - Serial Primary Key
• name - varchar(40)
• description - varchar(80)
• price - integer
• image_url - text

Note: SQLTabs may highlight name and description. Use them as your column names anyway, otherwise your Postman tests will fail.

Instructions

• Create a product table in your Heroku database.
• Create a folder called db.
  • Create a create_product.sql file.
  • Create a read_products.sql file.
  • Create a read_product.sql file.
  • Create a update_product.sql file.
  • Create a delete_product.sql file.
• create_product.sql:
  • The SQL should be able to add a new product to the products table.
  • The SQL should have four parameters ( name, description, price, image_url ).
• read_products.sql:
  • The SQL should be able to return all products from the product table.
• read_product.sql:
  • The SQL should be able to return a specific product from the product table.
  • The SQL should use a parameter to find the product whose product_id matches.
• update_product.sql:
  • The SQL should be able to update the description of a specific product from the product table.
  • The SQL should use a parameter to find the product whose product_id matches.
  • The SQL should use a parameter to update the value of the description.
• delete_product.sql:
  • The SQL should be able to delete a specific product from the product table.
  • The SQL should use a parameter to find the product whose product_id matches.

Detailed Instructions

Now that we have a method of connecting to our database and have an instance ready to go on app, we are ready to start creating the sql files that will interact with our database and a products table. Let's begin by creating a products table that follows the schema in the summary. The final syntax will look like:

CREATE TABLE product (
  product_id SERIAL PRIMARY KEY NOT NULL,
  name varchar(40) NOT NULL,
  description varchar(80) NOT NULL,
  price integer NOT NULL,
  image_url text NOT NULL
);

Now that we have a product table, we'll make five sql files. One for creating products; one for reading all products; one for reading a specific product; one for updating products; and one for deleting products. Let's create a folder called db. This is where we'll store our sql files that we can execute later using the database instance.

Inside the db folder, let's create a file called create_product.sql. This sql file will be responsible for creating a new product using four parameters. The four parameters are name, description, price, and image_url. To add something to a database we use the following syntax: INSERT INTO Table ( column1, column2 ) VALUES ( value1, value2 ); The values we'll change are Table, column, and value. Since we want to insert into the product table, we'll change Table to product. Since we are updating the name, description, price, and image_url, we'll use those as the columns. And since we are using parameters for the values, we'll use $1, $2, $3, and $4 as the values. The final syntax will look like:

INSERT INTO product ( name, description, price, image_url ) VALUES ( $1, $2, $3, $4 );

Now let's move on to read_products.sql. Create a file in the db folder called read_products.sql. This sql file will be responsible for reading all products from the database. To read all data from a database we use the following syntax: SELECT * FROM Table. Since we are working with the product table, we'll change Table to product. The final syntax will look like:

SELECT * FROM product;

Now let's move on to read_product.sql. Create a file in the db folder called read_product.sql. This file will be very similar to read_products.sql, however we need to add a where statement so we don't get all the products. We'll want to use a parameter so we can dynamically select a product by product_id. We can use a where statement with the following syntax: WHERE column1 = value. Since we are looking for a product by ID, we'll change column1 to product_id. And since we are using a parameter for the ID, we'll change value to $1. The final syntax will look like:

SELECT * FROM product WHERE product_id = $1;

Now let's move on to update_product.sql. Create a file in the db folder called update_product.sql. This sql file will be responsible for updating the description of a product by ID. To update data from a database we use the following syntax: UPDATE Table SET column1 = value1 WHERE condition. Since we are working with the product table we'll change Table to product. Since we are updating the description dynamically we'll set column1 to description and value1 to $2. And since we are updating products by ID we'll set condition to product_id = $1. The order of $1 and $2 doesn't matter as long as you following the same order in the controller file. I personally prefer (id, value) instead of (value, id). The final syntax will look like:

UPDATE product SET description = $2 WHERE product_id = $1;

Now let's move on to delete_product.sql. Create a file in the db folder called delete_product.sql. This sql file will be responsible for deleting a specific product by ID. To delete data from a database we use the following syntax: DELETE FROM Table WHERE condition. Since we are working with the product table, we'll change Table to product. Since we are deleting by product ID, we'll change condition to product_id = $1. The final syntax will look like:

DELETE FROM product WHERE product_id = $1;

Solution

CREATE TABLE product

CREATE TABLE product (
  product_id SERIAL PRIMARY KEY NOT NULL,
  name varchar(40) NOT NULL,
  description varchar(80) NOT NULL,
  price integer NOT NULL,
  image_url text NOT NULL
);

SQL

create_product.sql

INSERT INTO product ( name, description, price, image_url ) VALUES ( $1, $2, $3, $4 );

read_products.sql

SELECT * FROM product;

read_product.sql

SELECT * FROM product WHERE product_id = $1;

update_product.sql

UPDATE product SET description = $2 WHERE product_id = $1;

delete_product.sql

DELETE FROM product WHERE product_id = $1;

Step 4

Summary

In this step, we will create a products_controller.js file that will handle the logic of interacting with the database.

Instructions

• Create a products_controller.js file.
• Use module.exports to export an object with five methods.
  • create, getOne, getAll, update, and delete.
• Inside of each method, access the database instance.
• Inside of each method, use the correct SQL file.
  • create -> create_product.sql.
  • getOne -> read_product.sql.
  • getAll -> read_products.sql.
  • update -> update_product.sql.
  • delete -> delete_product.sql.
• Don't worry about the parameter(s) in this step.
• create, update, and delete should send status 200 on success and status 500 on failure with a message about how something went wrong.
• getOne should send status 200 and the product on success and status 500 on failure with a message about how something went wrong (you can chose your own phrasing). Make sure to log the error to your console so you can read it if anything goes wrong.
• getAll should send status 200 and the products on success and status 500 on failure with a message about how something went wrong (you can chose your own phrasing). Make sure to log the error to your console so you can read it if anything goes wrong.

Detailed Instructions

Now that we have all the sql files we'll need to interact with our database, let's create a controller that will execute the sql. Create a file called products_controller.js. In this file, use module.exports to export an object with five methods. All methods should capture req, res, and next and create a variable for the database instance off of req.app.

module.exports = {
  create: ( req, res, next ) => {
    const dbInstance = req.app.get('db');
  },

  getOne: ( req, res, next ) => {
    const dbInstance = req.app.get('db');
  },

  getAll: ( req, res, next ) => {
    const dbInstance = req.app.get('db');
  },

  update: ( req, res, next ) => {
    const dbInstance = req.app.get('db');
  },

  delete: ( req, res, next ) => {
    const dbInstance = req.app.get('db');
  }
};

Now that our methods have access to the dbInstance we can execute our sql files by chaining on .file_name. For example, if I wanted to execute read_product I would use dbInstance.read_product(). Knowing this we can execute our sql files in every method. Chain a .then to use res to sendStatus 200 and chain a .catch to use res to send status 500 with a message about how something went wrong (you can chose your own phrasing). Make sure to log the error to your console so you can read it if anything goes wrong. The getOne and getAll method should send product and products on success.

module.exports = {
  create: ( req, res, next ) => {
    const dbInstance = req.app.get('db');

    dbInstance.create_product()
      .then( () => res.sendStatus(200) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  },

  getOne: ( req, res, next ) => {
    const dbInstance = req.app.get('db');

    dbInstance.read_product()
      .then( product => res.status(200).send( product ) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  },

  getAll: ( req, res, next ) => {
    const dbInstance = req.app.get('db');

    dbInstance.read_products()
      .then( products => res.status(200).send( products ) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  },

  update: ( req, res, next ) => {
    const dbInstance = req.app.get('db');

    dbInstance.update_product()
      .then( () => res.sendStatus(200) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  },

  delete: ( req, res, next ) => {
    const dbInstance = req.app.get('db');

    dbInstance.delete_product()
      .then( () => res.sendStatus(200) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  }
};

We'll worry about how to use parameters after we configure our routes. For right now, this is all we need to do.

Solution

products_controller.js

module.exports = {
  create: ( req, res, next ) => {
    const dbInstance = req.app.get('db');

    dbInstance.create_product()
      .then( () => res.sendStatus(200) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  },

  getOne: ( req, res, next ) => {
    const dbInstance = req.app.get('db');

    dbInstance.read_product()
      .then( product => res.status(200).send( product ) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  },

  getAll: ( req, res, next ) => {
    const dbInstance = req.app.get('db');

    dbInstance.read_products()
      .then( products => res.status(200).send( products ) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  },

  update: ( req, res, next ) => {
    const dbInstance = req.app.get('db');

    dbInstance.update_product()
      .then( () => res.sendStatus(200) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  },

  delete: ( req, res, next ) => {
    const dbInstance = req.app.get('db');

    dbInstance.delete_product()
      .then( () => res.sendStatus(200) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  }
};

Step 5

Summary

In this step, we will create endpoints that will call the methods on our controller. We will also require our controller in index.js.

Instructions

• Create the following endpoints: ( request method, url, controller method )
  • GET - /api/products - getAll.
  • GET - /api/products/:id - getOne.
  • PUT - /api/products/:id?desc=... - update.
  • POST - /api/products - create.
  • DELETE - /api/products/:id - delete.

Solution

index.js

require("dotenv").config();
const express = require("express");
const massive = require("massive");
const products_controller = require("./products_controller");

const app = express();

const { SERVER_PORT, CONNECTION_STRING } = process.env;

massive(CONNECTION_STRING)
  .then(dbInstance => {
    app.set("db", dbInstance);
  })
  .catch(err => console.log(err));

app.use(express.json());

app.post('/api/products', products_controller.create);
app.get('/api/products', products_controller.getAll);
app.get('/api/products/:id', products_controller.getOne);
app.put('/api/products/:id', products_controller.update);
app.delete('/api/products/:id', products_controller.delete);

app.listen(SERVER_PORT, () => {
  console.log(`Server listening on port ${SERVER_PORT}.`);
});

Step 6

Summary

In this step, we'll modify the controller to use parameters or the request body.

Instructions

• Open products_controller.js.
• Modify update to use id from req.params and desc from req.query.
• Modify getOne to use id from req.params.
• Modify delete to use id from req.params.
• Modify the create to use name, description, price, and image_url from the request body.
• Something to remember, you do not need to use an array if you have only one argument to pass to the massive method.

Detailed Instructions

Now that we know how our routes are configured, we can update our controller to reflect those changes. We'll modify update to use id from the request parameters and the desc from the request query. We'll modify getOne to use id from the request parameters. We'll modify delete to use id from the request parameters. And we'll modify create to use name, description, price and image_url from the request body. When adding parameters to sql, all you have to do is pass in an array as the first argument and then the element(s) in the array map to $1, $2, etc... For example: dbInstance.create_product([ name, description, price, image_url ]), name is $1, description is $2, price is $3, and image_url is $4. Remember, if you have only one argument, you do not need to pass it in an array.

module.exports = {
  create: ( req, res, next ) => {
    const dbInstance = req.app.get('db');
    const { name, description, price, image_url } = req.body;

    dbInstance.create_product([ name, description, price, image_url ])
      .then( () => res.sendStatus(200) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  },

  getOne: ( req, res, next ) => {
    const dbInstance = req.app.get('db');
    const { id } = req.params;

    dbInstance.read_product( id )
      .then( product => res.status(200).send( product ) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  },

  getAll: ( req, res, next ) => {
    const dbInstance = req.app.get('db');

    dbInstance.read_products()
      .then( products => res.status(200).send( products ) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  },

  update: ( req, res, next ) => {
    const dbInstance = req.app.get('db');
    const { params, query } = req;

    dbInstance.update_product([ params.id, query.desc ])
      .then( () => res.sendStatus(200) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  },

  delete: ( req, res, next ) => {
    const dbInstance = req.app.get('db');
    const { id } = req.params;

    dbInstance.delete_product( id )
      .then( () => res.sendStatus(200) )
      .catch( err => {
        res.status(500).send({errorMessage: "Oops! Something went wrong. Our engineers have been informed!"});
        console.log(err)
      } );
  }
};

Solution

products_controller.js

module.exports = {
  create: (req, res, next) => {
    const dbInstance = req.app.get('db');
    const { name, description, price, image_url } = req.body;

    dbInstance.create_product([name, description, price, image_url])
      .then(() => res.sendStatus(200))
      .catch(err => {
        res.status(500).send({ errorMessage: "Oops! Something went wrong. Our engineers have been informed!" });
        console.log(err)
      });
  },

  getOne: (req, res, next) => {
    const dbInstance = req.app.get('db');
    const { id } = req.params;

    dbInstance.read_product(id)
      .then(product => res.status(200).send(product))
      .catch(err => {
        res.status(500).send({ errorMessage: "Oops! Something went wrong. Our engineers have been informed!" });
        console.log(err)
      });
  },

  getAll: (req, res, next) => {
    const dbInstance = req.app.get('db');

    dbInstance.read_products()
      .then(products => res.status(200).send(products))
      .catch(err => {
        res.status(500).send({ errorMessage: "Oops! Something went wrong. Our engineers have been informed!" });
        console.log(err)
      });
  },

  update: (req, res, next) => {
    const dbInstance = req.app.get('db');
    const { params, query } = req;

    dbInstance.update_product([params.id, query.desc])
      .then(() => res.sendStatus(200))
      .catch(err => {
        res.status(500).send({ errorMessage: "Oops! Something went wrong. Our engineers have been informed!" });
        console.log(err)
      });
  },

  delete: (req, res, next) => {
    const dbInstance = req.app.get('db');
    const { id } = req.params;

    dbInstance.delete_product(id)
      .then(() => res.sendStatus(200))
      .catch(err => {
        res.status(500).send({ errorMessage: "Oops! Something went wrong. Our engineers have been informed!" });
        console.log(err)
      });
  }
};

Step 7

Summary

In this step, we'll test to make sure all the endpoint are working.

Instructions

• Import the provided postman_collection into Postman and make sure all the tests pass.

Solution

Black Diamond

• Create a React front end to interact with your app.
• Use express static to serve up your React files from a build folder.
• Create a single view that can insert, read, update, and delete products.
• Create a second view that just reads the products and displays them in a pretty way (like Jane.com or amazon).

Resources

Massive

• Database Functions
• Express Example Note: In the example, they break up the connection string into pieces. We just use one long connection string

SQL

• SQL Teaching
• SQL Bolt

Contributions

If you see a problem or a typo, please fork, make the necessary changes, and create a pull request so we can review your changes and merge them into the master repo and branch.

Copyright

© DevMountain LLC, 2017. Unauthorized use and/or duplication of this material without express and written permission from DevMountain, LLC is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to DevMountain with appropriate and specific direction to the original content.