使用罗顿番茄API

Question

这是我为搜索“罗顿番茄”电影API而制作的Python模块。它将搜索结果缓存在SQLite数据库中。

我可以对缓存系统做什么改进？是否有更好的方法来存储API搜索的结果？

是否有更好的方法与API进行通信？

import urllib2
import json
import sqlite3
import time

# sqlite database file
cache_database = "movies.db"
# how many seconds before the entry expires 
cache_expiration = 60*60  # one hour

class Cache:
    def get_conn(self):
        """
        connect with the sqlite database
        """
        conn = sqlite3.connect(cache_database)
        c = conn.cursor()
        c.execute(""" CREATE TABLE IF NOT EXISTS movies(
                        search_query TEXT PRIMARY KEY,
                        page_number INT,
                        timestamp INTEGER,
                        search_results BLOB); """)
        return conn

    def get(self, search_query, page_number):
        """
        get the search results from the database
        """
        with self.get_conn() as conn:
            c = conn.cursor()
            query = """SELECT search_results FROM movies WHERE 
                       search_query = \"{search_query}\" AND 
                       page_number = {page_number} AND 
                      (strftime('%s', 'now') - timestamp) < {cache_expiration}"""

            query = query.format(search_query = search_query,
                                 page_number = page_number,
                                 cache_expiration = cache_expiration)
            results = "" 
            for a in c.execute(query):
                results = a
            return results

    def put(self, search_query, page_number, search_results):
        """
        put the results into the database
        """
        timestamp = int( time.time() )
        with self.get_conn() as conn:
            c = conn.cursor()
            insert = """ INSERT OR REPLACE INTO movies
                         (search_query, page_number, timestamp, search_results) VALUES
                        (\"{search_query}\", {page_number}, {timestamp}, ?); """

            insert = insert.format(search_query = search_query,
                                   page_number = page_number,
                                   timestamp = timestamp)
            c.execute(insert, (search_results,))
            conn.commit()

class Movie:

    api_key = ""
    userAgent = "MovieInfoBot/1.0"

    def search(self, query, results_per_page=25, page_number=1):
        """
        searches for movies: movie name, result limit, page number
        """
        cache = Cache()
        result = cache.get(query, page_number)
        if result != "":
            print "using cache"
            movie_json = result[0]
        else:
            print "using web"
            #format the url
            base_url = "http://api.rottentomatoes.com/api/public/v1.0/movies.json"
            url = "{base_url}?apikey={api_key}&q={search_term}&page_limit={results_per_page}&page={page_number}"
            param = {}
            param["base_url"] = base_url
            param["api_key"] = self.api_key
            param["search_term"] = urllib2.quote(query.encode("utf8"))
            param["results_per_page"] = results_per_page
            param["page_number"] = page_number
            url = url.format(**param)
            req = urllib2.Request(url, headers={ 'User-Agent': self.userAgent })
            movie_json = urllib2.urlopen(req).read()

            # put the results into the movie cache
            cache.put(query, page_number, movie_json)

        movie_dict = json.loads(movie_json)
        return movie_dict


movie = Movie()
movie.api_key = "xua5v8mbvermd2t9v5gyeaua"
data = movie.search("the wizard of oz")

print json.dumps(data, indent=4)

下面是GitHub https://github.com/kylelk/Rotten-Tomatoes上的模块

Answer 1

这是个不错的剧本！(你应该开放源代码，我会使用它。)

准备的报表

您应该在查询中使用准备好的语句。它不仅更容易写，而且更有效率。例如：

def get(self, search_query, page_number):
    with self.get_conn() as conn:
        c = conn.cursor()
        query = """SELECT search_results FROM movies
                   WHERE search_query = ?
                   AND page_number = ?
                   AND strftime('%s', 'now') - timestamp < ?; """

        c.execute(query, (search_query, page_number, cache_expiration))
        return c.fetchone()

请注意，您不需要再担心引用。

您也可以对您的Cache.put方法执行相同的操作：

def put(self, search_query, page_number, search_results):
    timestamp = int(time.time())
    with self.get_conn() as conn:
        c = conn.cursor()
        insert = """INSERT OR REPLACE INTO movies
                    (search_query, page_number, timestamp, search_results)
                    VALUES (?, ?, ?, ?); """

        c.execute(insert, (search_query, page_number, timestamp, search_results,))
        conn.commit()

语句可以简化为

而不是这样：

results = "" 
for a in c.execute(query):
    results = a
return results

这样会更简单、更干净：

c.execute(query)
return c.fetchone()

除非，您确实希望迭代多个结果，并且只返回最后一个结果，就像在原始代码中一样。

Python类

现代类应该扩展object，例如：

class Cache(object):
    ...

class Movie(object):
    ...

编码风格

您可以简化这一点：

if result != "":
    ...

就像这样：

if result:
    ...

遵循PEP8 (官方的Python风格指南)是很好的。