recipes

Save a penny and find recipes with ingredients you already have at home 🥘.

Links:

• Website: https://savepenny.herokuapp.com/

Prerequisites

• Git
• Ruby 3.1
• Postgres 13
• Heroku CLI

Setup

1. Check out the repository

$ git clone git@github.com:frodsan/recipes.git

2. Run setup script

Run the following commands to install dependencies and setup the database.

$ bin/setup

3. Start the development server

You can start the server using the command given below.

$ bin/dev

And now you can visit the site with the URL http://localhost:3000.

Description

The application help users to find recipes by the ingredients they have.

Data Seeds

The dataset can be found in db/seeds/recipes-en.json and it has been populated into the database by rails db:seed. You can find the code here: db/seeds.rb.

Database Structure

The format of the JSON objects found in the dataset is:

{
  "title": "Golden Sweet Cornbread",
  "cook_time": 25,
  "prep_time": 10,
  "ingredients": [
    "1 cup all-purpose flour",
    "1 cup yellow cornmeal",
    "⅔ cup white sugar",
    "1 teaspoon salt",
    "3 ½ teaspoons baking powder",
    "1 egg",
    "1 cup milk",
    "⅓ cup vegetable oil"
  ],
  "ratings": 4.74,
  "cuisine": "",
  "category": "Cornbread",
  "author": "bluegirl",
  "image": "https://images.url/image.jpg"
}

I've created the recipes table with the same structure as the JSON object for simplicity. I've decided to use jsonb as the type for the ingredients field, so it's straightforward to read it from Rails, but also, there is no need to do any data transformation since I planned to use Postgres' search features.

Searching recipes by ingredients

Since the ingredients field uses jsonb, it is possible to parse each string in the JSON array into a tsvector, a sorted list of normalized lexemes:

# select to_tsvector('english', '[
#     "1 cup all-purpose flour",
#     "1 cup yellow cornmeal"
# ]') as ts_vector;
                                  ts_vector
--------------------------------------------------------------------------------
 '1':1,7 'all-purpos':3 'cornmeal':10 'cup':2,8 'flour':6 'purpos':5 'yellow':9

Then, I decided to use the websearch_to_tsquery function, which provides search capabilities sort of like the ones used by search engines:

# -- Search by cornmeal and flour
# select to_tsvector('english', '[
#   "1 cup all-purpose flour",
#   "1 cup yellow cornmeal"
# ]') @@ websearch_to_tsquery('cornmeal flour') as must_be_true;
 must_be_true
--------------
 t

# -- Search by cornmeal but not flour
# select to_tsvector('english', '[
#   "1 cup all-purpose flour",
#   "1 cup yellow cornmeal"
# ]') @@ websearch_to_tsquery('cornmeal -flour') as must_be_false;
 must_be_false
--------------
 f

This is how is implemented in the model:

class Recipe < ApplicationRecord
  scope :by_ingredients, -> (query) {
    where("to_tsvector('english', ingredients) @@ websearch_to_tsquery(?)", query)
  }
end

Also, I've created an index on the function result to speed up the queries:

add_index :recipes, "to_tsvector('english', ingredients)", using: :gin

Explaining the query shows that the it uses the index:

> Recipe.by_ingredients('pasta, eggplant').explain
EXPLAIN for: SELECT "recipes".* FROM "recipes" WHERE (to_tsvector('english', ingredients) @@ websearch_to_tsquery('pasta, eggplant'))
                                                    QUERY PLAN
------------------------------------------------------------------------------------------------------------------
 Index Scan using index_recipes_on_to_tsvector_english_ingredients on recipes  (cost=0.11..6.11 rows=2 width=525)
   Index Cond: (to_tsvector('english'::regconfig, ingredients) @@ websearch_to_tsquery('pasta, eggplant'::text))
(2 rows)

Putting everything together

The rest is standard Rails code which can be found here:

• app/models/recipe.rb
• app/controllers/recipes_controller.rb
• app/views/recipes/