PG::SyntaxError at /bookmarks - I'm unable to work out why the SQL query is wrong - postgresql

Question

When running my application using sinatra, I get the error message PG::SyntaxError at /bookmarks
ERROR: syntax error at or near "{" LINE 1: SELECT * FROM users WHERE id = {:id=>"5"} ^
It happens when I click the submit button on /users/new route which should then take me to index route /.
The backtrace provides the following information
/Users/BartJudge/Desktop/Makers_2018/bookmark-manager-2019/lib/database_connection.rb in async_exec
#connection.exec(sql)
/Users/BartJudge/Desktop/Makers_2018/bookmark-manager-2019/lib/database_connection.rb in query
#connection.exec(sql)
/Users/BartJudge/Desktop/Makers_2018/bookmark-manager-2019/lib/user.rb in find
result = DatabaseConnection.query("SELECT * FROM users WHERE id = #{id}")
app.rb in block in <class:BookmarkManager>
#user = User.find(id: session[:user_id])
This is the database_connection file
require 'pg'
class DatabaseConnection
def self.setup(dbname)
#connection = PG.connect(dbname: dbname)
end
def self.connection
#connection
end
def self.query(sql)
#connection.exec(sql)
end
end
This is the user model
require_relative './database_connection'
require 'bcrypt'
class User
def self.create(email:, password:)
encypted_password = BCrypt::Password.create(password
)
result = DatabaseConnection.query("INSERT INTO users (email, password) VALUES('#{email}', '#{encypted_password}') RETURNING id, email;")
User.new(id: result[0]['id'], email: result[0]['email'])
end
attr_reader :id, :email
def initialize(id:, email:)
#id = id
#email = email
end
def self.find(id)
return nil unless id
result = DatabaseConnection.query("SELECT * FROM users WHERE id = #{id}")
User.new(
id: result[0]['id'],
email: result[0]['email'])
end
end
This is the controller
require 'sinatra/base'
require './lib/bookmark'
require './lib/user'
require './database_connection_setup.rb'
require 'uri'
require 'sinatra/flash'
require_relative './lib/tag'
require_relative './lib/bookmark_tag'
class BookmarkManager < Sinatra::Base
enable :sessions, :method_override
register Sinatra::Flash
get '/' do
"Bookmark Manager"
end
get '/bookmarks' do
#user = User.find(id: session[:user_id])
#bookmarks = Bookmark.all
erb :'bookmarks/index'
end
post '/bookmarks' do
flash[:notice] = "You must submit a valid URL" unless Bookmark.create(url: params[:url], title: params[:title])
redirect '/bookmarks'
end
get '/bookmarks/new' do
erb :'bookmarks/new'
end
delete '/bookmarks/:id' do
Bookmark.delete(id: params[:id])
redirect '/bookmarks'
end
patch '/bookmarks/:id' do
Bookmark.update(id: params[:id], title: params[:title], url: params[:url])
redirect('/bookmarks')
end
get '/bookmarks/:id/edit' do
#bookmark = Bookmark.find(id: params[:id])
erb :'bookmarks/edit'
end
get '/bookmarks/:id/comments/new' do
#bookmark_id = params[:id]
erb :'comments/new'
end
post '/bookmarks/:id/comments' do
Comment.create(text: params[:comment], bookmark_id: params[:id])
redirect '/bookmarks'
end
get '/bookmarks/:id/tags/new' do
#bookmark_id = params[:id]
erb :'/tags/new'
end
post '/bookmarks:id/tags' do
tag = Tag.create(content: params[:tag])
BookmarkTag.create(bookmark_id: params[:id], tag_id: tag.id)
redirect '/bookmarks'
end
get '/users/new' do
erb :'users/new'
end
post '/users' do
user = User.create(email: params[:email], password: params[:password])
session[:user_id] = user.id
redirect '/bookmarks'
end
run! if app_file == $0
end
self.find(id), in the user model, is where the potentially offending SQL query resides.
I've tried;
"SELECT * FROM users WHERE id = #{id}"
and "SELECT * FROM users WHERE id = '#{id}'"
Beyond that, I'm stumped. The query looks fine, but sinatra is having none of it.
Hopefully someone can help me resolve this.
Thanks, in advance.

Answer 1

You're call find with a hash argument:
User.find(id: session[:user_id])
but it is expecting just the id:
class User
...
def self.find(id)
...
end
...
end
Then you end up interpolating a hash into your SQL string which results in invalid HTML.
You should be saying:
#user = User.find(session[:user_id])
to pass in just the id that User.find expects.
You're also leaving yourself open to SQL injection issues because you're using unprotected string interpolation for your queries rather than placeholders.
Your query method should use exec_params instead of exec and it should take some extra parameters for the placeholder values:
class DatabaseConnection
def self.query(sql, *values)
#connection.exec_params(sql, values)
end
end
Then things that call query should use placeholders in the SQL and pass the values separately:
result = DatabaseConnection.query(%q(
INSERT INTO users (email, password)
VALUES($1, $2) RETURNING id, email
), email, encypted_password)
result = DatabaseConnection.query('SELECT * FROM users WHERE id = $1', id)
...