390 lines
13 KiB
Rust
390 lines
13 KiB
Rust
/// This demo application uses a sqlite file to store some data. It does *not* use ORM (that would
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/// be done with the `diesel` crate.)!
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///
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/// A very useful ressource is the
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/// [rust-cookbook](https://rust-lang-nursery.github.io/rust-cookbook/database/sqlite.html).
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use std::io::{BufRead, Write};
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use std::path::PathBuf;
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use std::{env, fs, io};
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use rusqlite::{Connection, Rows};
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const DBNAME: &str = "cats.db";
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const TABLE_CAT_COLOR: &str = "cat_colors";
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const TABLE_CAT: &str = "cats";
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const USAGE_DELETE: &str = "Usage:
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> D cat 15 (to delete cat with id 15)
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> D cat 15 16 (to delete cat with id 15 and 16)
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> D color 5 (to delete color with id 5)";
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fn connect() -> anyhow::Result<Connection> {
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let mut wd = env::current_dir()?;
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let mut dbpath: Option<PathBuf> = None;
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// does the current directory have a data/cats.db ? (the file need not exist, we can create it
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// if data exists)
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{
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let mut wddata = wd.clone();
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wddata.push("data");
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if wddata.exists() {
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println!("found {DBNAME} in {:?}", &wddata);
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wddata.push(DBNAME);
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dbpath = Some(wddata);
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}
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}
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// otherwise, does the current or any higher directories contain a cats.db ?
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'search_dir: while dbpath.is_none() {
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for entry in fs::read_dir(&wd)? {
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let entry = entry?;
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if entry.file_name() == DBNAME {
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println!("found {DBNAME} in {:?}", wd);
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dbpath = Some(entry.path());
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break 'search_dir;
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}
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}
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if !wd.pop() {
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// we are at the root!
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break 'search_dir;
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}
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}
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// if all fails, use $PWD/data/cats.db
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if dbpath.is_none() {
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println!(
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"No {DBNAME} found, using {:?}/data/{DBNAME}",
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env::current_dir()?
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);
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fs::create_dir("data")?;
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let mut path = env::current_dir()?;
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path.push("data");
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path.push(DBNAME);
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dbpath = Some(path);
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}
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let conn = Connection::open(dbpath.unwrap())?;
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Ok(conn)
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}
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fn setup(conn: &Connection) -> anyhow::Result<()> {
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conn.execute(
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&format!(
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"CREATE TABLE IF NOT EXISTS {TABLE_CAT_COLOR} (
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id INTEGER PRIMARY KEY,
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name TEXT NOT NULL UNIQUE COLLATE NOCASE
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)"
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),
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(),
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)?;
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conn.execute(
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&format!(
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"CREATE TABLE IF NOT EXISTS {TABLE_CAT} (
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id INTEGER PRIMARY KEY,
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name TEXT NOT NULL COLLATE NOCASE,
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color_id INTEGER NOT NULL REFERENCES CAT_COLORS(ID)
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)"
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),
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(),
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)?;
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Ok(())
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}
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// color names are unique, so we use the color name instead of the id because it's easier
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fn check_if_color_exists(conn: &Connection, color: &str) -> anyhow::Result<bool> {
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let mut stmt = conn.prepare(&format!(
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"SELECT EXISTS( SELECT 1 FROM {TABLE_CAT_COLOR} WHERE name = (LOWER(?1)))"
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))?;
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// we need the return or the temporary result is dropped somehow
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#[allow(clippy::needless_return)]
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return Ok(stmt
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.query([color.to_string()])?
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.next()?
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.unwrap()
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.get::<usize, usize>(0)?
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== 1);
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}
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// note that cat names are not UNIQUE, so we need to use the id instead
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fn check_if_cat_exists(conn: &Connection, id: usize) -> anyhow::Result<bool> {
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let mut stmt = conn.prepare(&format!(
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"SELECT EXISTS( SELECT 1 FROM {TABLE_CAT} WHERE id = (?1))"
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))?;
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// we need the return or the temporary result is dropped somehow
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#[allow(clippy::needless_return)]
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return Ok(stmt.query([id])?.next()?.unwrap().get::<usize, usize>(0)? == 1);
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}
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/// Add a new color to the cat_colors table
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///
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/// Will fail if the sql fails
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///
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/// If the color already exists, will return Ok(id)
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///
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/// The table stores the name in lowercase
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///
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/// Returns the id of the color
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fn new_color(conn: &Connection, color: &str) -> anyhow::Result<usize> {
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if check_if_color_exists(conn, color)? {
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return Ok(get_color_id(conn, color)?);
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}
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conn.execute(
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&format!("INSERT INTO {TABLE_CAT_COLOR} (name) VALUES (LOWER(?1))"),
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[color.to_string()],
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)?;
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Ok(get_color_id(conn, color)?)
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}
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fn get_color_id(conn: &Connection, color: &str) -> anyhow::Result<usize> {
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Ok(conn.query_row(
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&format!("SELECT id FROM {TABLE_CAT_COLOR} WHERE name = (LOWER(?1))"),
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[color.to_string()],
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|row| row.get::<usize, usize>(0),
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)?)
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}
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fn get_color_by_id(conn: &Connection, id: usize) -> anyhow::Result<Option<String>> {
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let maybe = conn.query_row(
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&format!("SELECT name FROM {TABLE_CAT_COLOR} WHERE id = (?1)"),
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[id.to_string()],
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|row| row.get::<usize, String>(0),
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);
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if let Result::Ok(color) = maybe {
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Ok(Some(color))
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} else {
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let err: rusqlite::Error = maybe.unwrap_err();
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if matches!(err, rusqlite::Error::QueryReturnedNoRows) {
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Ok(None)
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} else {
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Err(err.into())
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}
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}
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}
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fn new_cat(conn: &Connection, name: &str, color_id: usize) -> anyhow::Result<usize> {
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conn.execute(
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&format!("INSERT INTO {TABLE_CAT} (name, color_id) VALUES (LOWER(?1), ?2)"),
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[name.to_string(), color_id.to_string()],
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)?;
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Ok(conn.last_insert_rowid() as usize)
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}
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fn get_cat_color(conn: &Connection, id: usize) -> anyhow::Result<String> {
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Ok(conn.query_row(
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&format!("SELECT cc.name FROM {TABLE_CAT_COLOR} cc, {TABLE_CAT} c WHERE c.id = (?1) AND c.color_id = cc.id"),
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[id.to_string()],
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|row| row.get::<usize, String>(0),
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)?)
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}
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fn interactive_add_cat(conn: &Connection) -> anyhow::Result<usize> {
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let stdin = io::stdin();
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print!("the name of your cat?\n> ");
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io::stdout().flush()?;
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let mut cat_name: String = String::new();
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let _ = stdin.read_line(&mut cat_name)?;
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cat_name = cat_name.trim().to_string();
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print!("the color of your cat?\n> ");
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io::stdout().flush()?;
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let mut cat_color: String = String::new();
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let _ = stdin.read_line(&mut cat_color)?;
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cat_color = cat_color.trim().to_string();
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new_color(conn, &cat_color)?;
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let cat_id = new_cat(conn, &cat_name, get_color_id(conn, &cat_color)?)?;
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assert!(check_if_cat_exists(conn, cat_id)?);
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println!("your cat has id {cat_id}");
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println!("your cat has color '{}'", get_cat_color(conn, cat_id)?);
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Ok(cat_id)
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}
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fn interactive_find_cat(conn: &Connection) -> anyhow::Result<()> {
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let stdin = io::stdin();
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print!("the name of your cat?\n> ");
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io::stdout().flush()?;
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let mut cat_name: String = String::new();
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let _ = stdin.read_line(&mut cat_name)?;
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cat_name = cat_name.trim().to_string();
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print!("the color of your cat?\n> ");
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io::stdout().flush()?;
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let mut cat_color: String = String::new();
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let _ = stdin.read_line(&mut cat_color)?;
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cat_color = cat_color.trim().to_string();
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let mut stmt = conn.prepare(&format!(
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"SELECT * FROM {TABLE_CAT} c, {TABLE_CAT_COLOR} cc
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WHERE c.color_id = cc.id
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AND (c.name LIKE (?1) OR cc.name LIKE (?2))"
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))?;
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let mut fitting_cats = stmt.query([cat_name, cat_color])?;
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println!("These cats might fit your description:\n");
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print_cats(conn, &mut fitting_cats)?;
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Ok(())
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}
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fn print_colors(_conn: &Connection, colors: &mut Rows) -> anyhow::Result<()> {
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println!("{: <14}| {: <19}", "id", "name");
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println!("{:=^80}", "");
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while let Some(color) = colors.next()? {
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println!(
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"{:<14}| {: <19}",
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color.get::<_, usize>(0)?,
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color.get::<_, String>(1)?
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)
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}
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Ok(())
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}
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fn print_cats(conn: &Connection, cats: &mut Rows) -> anyhow::Result<()> {
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println!(
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"{: <14}| {: <19}| {: <19} -> {: <19}",
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"id", "name", "color id", "color name"
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);
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println!("{:=^80}", "");
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while let Some(cat) = cats.next()? {
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println!(
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"{: <14}| {: <19}| {: <19} -> {: <19}",
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cat.get::<_, usize>(0)?,
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cat.get::<_, String>(1)?,
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cat.get::<_, usize>(2)?,
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get_color_by_id(conn, cat.get::<_, usize>(2)?)?.expect("no color for this id"),
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)
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}
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Ok(())
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}
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fn print_all_data(conn: &Connection) -> anyhow::Result<()> {
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println!("Cat colors:");
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let mut stmt = conn.prepare(&format!("SELECT * FROM {TABLE_CAT_COLOR}"))?;
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let mut colors = stmt.query([])?;
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print_colors(conn, &mut colors)?;
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println!("\n\nCats:");
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let mut stmt = conn.prepare(&format!("SELECT * FROM {TABLE_CAT}"))?;
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let mut cats = stmt.query([])?;
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print_cats(conn, &mut cats)?;
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Ok(())
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}
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fn main() -> anyhow::Result<()> {
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let conn = connect()?;
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setup(&conn)?;
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let stdin = io::stdin();
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let mut buf: String = String::new();
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loop {
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buf.clear();
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print!("{}[2J", 27 as char); // clear terminal
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io::stdout().flush()?;
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print!("(A)dd a cat, (F)ind a cat, (P)rint out all data, (D)elete data, or (E)xit?\n> ");
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io::stdout().flush()?;
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let _ = stdin.lock().read_line(&mut buf);
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buf = buf.trim().to_string();
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buf = buf.to_uppercase().to_string();
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if buf.starts_with("A") {
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interactive_add_cat(&conn)?;
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} else if buf.starts_with("F") {
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interactive_find_cat(&conn)?;
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} else if buf.starts_with("P") {
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print_all_data(&conn)?;
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} else if buf.starts_with("D") {
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let words: Vec<&str> = buf.split(' ').collect();
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dbg!(&words);
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if words.len() < 2 {
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println!("{USAGE_DELETE}");
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} else {
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let mode = words[1];
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let nums: Vec<usize> = words[2..]
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.iter()
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.map(|word| {
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word.parse::<usize>()
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.expect("could not parse db integer to rust integer")
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})
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.collect();
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dbg!(&nums);
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match mode {
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"CAT" => {
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let mut stmt =
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conn.prepare(&format!("DELETE FROM {TABLE_CAT} WHERE id = (?1)"))?;
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for n in nums {
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stmt.execute([n])?;
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}
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}
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"COLOR" => {
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// Cats have colors, so if we delete a color, we need to delete cats with
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// that color too.
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let mut stmt_how_many_cats_with_color = conn.prepare(&format!(
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"SELECT cc.id FROM {TABLE_CAT} c, {TABLE_CAT_COLOR}
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cc WHERE c.color_id = (?1)"
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))?;
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let mut stmt_cats_with_color = conn.prepare(&format!(
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"SELECT cc.id FROM {TABLE_CAT} c, {TABLE_CAT_COLOR}
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cc WHERE c.color_id = (?1)"
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))?;
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for color_id in &nums {
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let cats_amount: usize = stmt_how_many_cats_with_color
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.query_row([color_id], |row| row.get::<_, usize>(0))?;
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if cats_amount > 0 {
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// FIXME: cats is empty?
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let mut cats = stmt_cats_with_color.query([color_id])?;
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let mut cat_ids: Vec<usize> = Vec::new();
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while let Some(cat) = cats.next()? {
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cat_ids.push(cat.get::<_, usize>(0)?);
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}
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println!("You are about to also delete these cats, as they have the color id {color_id}. Type 'YES' to confirm");
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print_cats(&conn, &mut cats)?;
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buf.clear();
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let _ = stdin.lock().read_line(&mut buf); // wait for enter as confirmation
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buf = buf.trim().to_string();
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buf = buf.to_uppercase().to_string();
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if buf.as_str() != "YES" {
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continue;
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}
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// FIXME: I DELETED ALL THE CATS OH NO
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let mut stmt = conn
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.prepare(&format!("DELETE FROM {TABLE_CAT} WHERE id = (?1)"))?;
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for cat_id in cat_ids {
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stmt.execute([cat_id])?;
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}
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}
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let mut stmt = conn.prepare(&format!(
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"DELETE FROM {TABLE_CAT_COLOR} WHERE id = (?1)"
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))?;
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let _ = nums.iter().map(|n| stmt.execute([n]));
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}
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}
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_ => {
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println!("{USAGE_DELETE}");
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}
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}
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}
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} else if buf.starts_with("E") {
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println!("Goodbye");
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break;
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}
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println!("\n(Enter to continue)");
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let _ = stdin.lock().read_line(&mut buf); // wait for enter as confirmation
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}
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Ok(())
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}
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