library/dbLayer.py

import sqlite3

dbFile = 'sqLibrary.db'
bookTable = 'books'
bookRemovedTable='books_deleted'
bookCategoryTable='book_categories'

bookTableCreation = '''
CREATE TABLE IF NOT EXISTS books
    (id INTEGER PRIMARY KEY, 
     isbn, lccn, title, subtitle, authors, edition, 
     publisher, publish_year, publish_month, publish_location, 
     pages, pagination, weight, last_updated);

CREATE TABLE IF NOT EXISTS books_deleted
    (id INTEGER PRIMARY KEY, 
     isbn, lccn, title, subtitle, authors, edition, 
     publisher, publish_year, publish_month, publish_location, 
     pages, pagination, weight, last_updated);

CREATE TABLE IF NOT EXISTS categories
    (cat_id INTEGER PRIMARY KEY, category STRING);

CREATE TABLE IF NOT EXISTS book_categories
    (id INTEGER, cat_id INTEGER);

CREATE TABLE IF NOT EXISTS book_deleted_categories
    (id INTEGER, cat_id INTEGER);
'''

columns = ['id', 'isbn', 'lccn',
           'title', 'subtitle', 'authors', 'edition', 
           'publisher', 'publish year', 'publish month', 'publish location', 
           'pages', 'pagination', 'weight', 'last updated']

bookTriggerCreation = '''
CREATE TRIGGER IF NOT EXISTS insert_books_time AFTER INSERT ON books
BEGIN
    UPDATE books SET last_updated = DATETIME('NOW') WHERE rowid = new.rowid;
END;

CREATE TRIGGER IF NOT EXISTS update_books_time AFTER UPDATE ON books
BEGIN
    UPDATE books SET last_updated = DATETIME('NOW') WHERE rowid = new.rowid;
END;

CREATE TRIGGER IF NOT EXISTS delete_books_backup BEFORE DELETE ON books
BEGIN
    INSERT INTO books_deleted (isbn, lccn, 
                title, subtitle, authors, edition, 
                publisher, publish_year, publish_month, publish_location, 
                pages, pagination, weight, last_updated)
            SELECT isbn, lccn, 
                   title, subtitle, authors, edition, 
                   publisher, publish_year, publish_month, publish_location, 
                   pages, pagination, weight, last_updated
                   FROM books
                   WHERE rowid = old.rowid;
END;

CREATE TRIGGER IF NOT EXISTS insert_book_category_time AFTER INSERT ON book_categories
BEGIN
    UPDATE books SET last_updated = DATETIME('NOW') WHERE id = new.id;
END;

CREATE TRIGGER IF NOT EXISTS delete_book_category_time AFTER DELETE ON book_categories
BEGIN
    UPDATE books SET last_updated = DATETIME('NOW') WHERE id = old.id;
END;
'''

def colify(s):
    return s.replace(" ","_").lower()

# escapes strings and such
def stringify(v):
    return '"' + str(v).strip().replace('"','""') + '"'

def addBook(book):
    conn = sqlite3.connect(dbFile)
    c = conn.cursor()
    cols = []
    vals = []
    for k,v in book.items():
        if v!="":
            cols.append(colify(k))
            vals.append(stringify(v))
    
    query = "INSERT INTO "+bookTable+" ("+", ".join(cols)+") VALUES ("+", ".join(vals)+");"
    c.execute(query)
    conn.commit()
    c.close()

def updateBook(book, bookID):
    conn = sqlite3.connect(dbFile)
    c = conn.cursor()
    updates=[]
    for k,v in book.items():
        updates.append(colify(k)+"="+stringify(v))
    query = "UPDATE "+bookTable+" SET " +  ", ".join(updates)+" WHERE id = " +str(bookID)+";"
    c.execute(query)
    conn.commit()
    c.close()

def getBooks():
    conn = sqlite3.connect(dbFile)
    c = conn.cursor()
    query = "SELECT * FROM "+bookTable+";"
    c.execute(query)
    books = []
    for b in c:
        book = {}
        i = 0
        for k in columns:
            if b[i]!=None:
                book[k]=b[i]
            i+=1
        books.append(book)
    c.close()
    return books

def getRemovedBooks():
    conn = sqlite3.connect(dbFile)
    c = conn.cursor()
    query = "SELECT * FROM "+bookRemovedTable+";"
    c.execute(query)
    books = []
    for b in c:
        book = {}
        i = 0
        for k in columns:
            if b[i]!=None:
                book[k]=b[i]
            i+=1
        books.append(book)
    c.close()
    return books

def getBookByID(bookid):
    conn = sqlite3.connect(dbFile)
    c = conn.cursor()
    query = "SELECT * FROM "+bookTable+" WHERE id = "+str(bookid)+";"
    c.execute(query)
    b = c.fetchone()
    book = {}
    i=0
    for k in columns:
        if b[i]!=None:
            book[k]=b[i]
        i+=1
    c.close()
    return book

# removes book from catalogue
def removeBook(bookid):
    conn = sqlite3.connect(dbFile)
    c = conn.cursor()
    query = "DELETE FROM " +bookTable+ " WHERE id = "+str(bookid)+";"
    c.execute(query)
    query = "DELETE FROM " +bookCategoryTable+ " WHERE id = "+str(bookid)+";"
    c.execute(query)
    conn.commit()
    c.close()

# fully deletes book from removedBooks table
def deleteBook(bookid):
    conn = sqlite3.connect(dbFile)
    c = conn.cursor()
    query = "DELETE FROM " +bookRemovedTable+ " WHERE id = "+str(bookid)+";"
    c.execute(query)
    conn.commit()
    c.close()


def createBooksTable():
    conn = sqlite3.connect(dbFile)
    c = conn.cursor()
    c.executescript(bookTableCreation)
    conn.commit()
    c.close()

def createTriggers():
    conn = sqlite3.connect(dbFile)
    c = conn.cursor()
    c.executescript(bookTriggerCreation)
    conn.commit()
    c.close()

createBooksTable()
createTriggers()