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William Carroll c38814d7a1 Add CHECK constraints to schema I believe data should be validated at each level of the stack: - database - server - client The database, in my opinion, is the most important layer at which to validate because you can eliminate entire classes of bugs. However, the CHECK constraint is limited, and the more complex the predicates are, the more expensive database operations become. At the server and client layers, the data validations can be more sophisticated and return more useful error messages to help users better understand the shape of the data that our application expects.		2020-07-27 14:23:34 +01:00
data	Define table schema and CSVs to populate the database	2020-07-27 11:16:26 +01:00
src	Add CHECK constraints to schema	2020-07-27 14:23:34 +01:00
.gitignore	Define table schema and CSVs to populate the database	2020-07-27 11:16:26 +01:00
README.md	Add instruction for operating the server	2020-07-27 11:36:09 +01:00
shell.nix	Integrate Persistent with Servant	2020-07-24 22:48:08 +01:00
todo.org	Create todo.org	2020-07-24 18:58:04 +01:00

TopTal take-home #2

All of the commands defined herein should be run from the top-level directory of this repository (i.e. the directory in which this file exists).

Server

To create the environment that contains all of this application's dependencies, run:

$ nix-shell

To run the server interactively, run:

$ cd src/
$ ghci

Now compile and load the server with:

Prelude> :l Main.hs
*Main> main

Create a new database named db.sqlite3 with:

$ sqlite3 db.sqlite3

Initialize the schema with:

sqlite> .read src/init.sql

You can verify that you successfully initialized the database by running:

sqlite> .tables
sqlite> .schema Accounts
sqlite> .schema Trips

Populate the database with some dummy values using the following:

sqlite> PRAGMA foreign_keys = on;
sqlite> .mode csv
sqlite> .import data/accounts.csv Accounts
sqlite> .import data/trips.csv Trips

You can verify you successfully populated the tables with:

sqlite> .mode columns
sqlite> .headers on
sqlite> SELECT * FROM Accounts;
sqlite> SELECT * FROM Trips;