本節(jié)內(nèi)容
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講django的models之前， 先來想一想， 讓你通過django操作數(shù)據(jù)庫，你怎么做？ 做苦思冥想，可能會(huì)這樣寫。
| 12345678910111213141516 | import?pymysql??def?index(request):????# 創(chuàng)建連接????conn?=?pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='alex123', db='luffy_dev')????# 創(chuàng)建游標(biāo)????cursor?=?conn.cursor()?????cursor.execute("select username,email,mobile from web_account")????data_set?=?cursor.fetchall()?????cursor.close()????conn.close()?????return?HttpResponse(data_set) |
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很方便就實(shí)現(xiàn)了從數(shù)據(jù)庫里取數(shù)據(jù)，事實(shí)上，很多人確實(shí)就是這么做的。但這樣做會(huì)帶來2個(gè)問題
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那怎么辦呢？ORM提供了新思路。
對象關(guān)系映射(Object Relational Mapping)，它的實(shí)質(zhì)就是將關(guān)系數(shù)據(jù)（庫）中的業(yè)務(wù)數(shù)據(jù)用對象的形式表示出來，并通過面向?qū)ο螅∣bject-Oriented）的方式將這些對象組織起來，實(shí)現(xiàn)系統(tǒng)業(yè)務(wù)邏輯的過程。
在ORM過程中最重要的概念是映射（Mapping），通過這種映射可以使業(yè)務(wù)對象與數(shù)據(jù)庫分離。從面向?qū)ο髞碚f，數(shù)據(jù)庫不應(yīng)該和業(yè)務(wù)邏輯綁定到一起，ORM則起到這樣的分離作用，使數(shù)據(jù)庫層透明，開發(fā)人員真正的面向?qū)ο蟆?/p>
上面的解釋有點(diǎn)蒙蔽對不？其實(shí)你只需要抓住2個(gè)關(guān)鍵詞， “映射” 和 “對象”，就能知道orm是什么干什么的了。
看下面的圖，就是直觀的例子，把右邊的表結(jié)構(gòu)映射成了左邊的類
ORM可以使你不用再寫原生SQL, 而是像操作對象一樣就可以實(shí)現(xiàn)對表里數(shù)據(jù)的增刪改查
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好棒棒，媽媽再也不用逼你寫原生sql啦！
但是不要開心太早，ORM確實(shí)提高了開發(fā)效率，并且降低了數(shù)據(jù)操作與代碼之間的耦合，不過有利就有弊，我們總結(jié)一下orm的優(yōu)缺點(diǎn)。
優(yōu)點(diǎn)：
缺點(diǎn)：
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講Django為什么說ORM? 哈，? 好啦，是時(shí)候該引出主角啦，因?yàn)镈jango的models基于架構(gòu)ORM實(shí)現(xiàn)的。
Django 的models把數(shù)據(jù)庫表結(jié)構(gòu)映射成了一個(gè)個(gè)的類， 表里的每個(gè)字段就是類的屬性。我們都知道數(shù)據(jù)庫有很多字段類型，int,float,char等， Django的models類針對不同的字段也設(shè)置了不同的類屬性。
| 12345678910111213141516171819202122232425 | AutoField?????????#An IntegerField that automatically increments according to available IDsBigAutoField??????#A 64-bit integer, guaranteed to fit numbers from 1 to 9223372036854775807.BigIntegerField???#-9223372036854775808 to 9223372036854775807BinaryField???????#A field to store raw binary data. It only supports bytes assignmentBooleanField???CharFieldDateField?????????#e.g 2019-04-27DateTimeField?????#e.g 2019-04-27 17:53:21DecimalField?????DurationField?????#storing periods of time ,e.g [DD] [HH:[MM:]]ss[.uuuuuu]"EmailFieldFileField?????????#存儲(chǔ)文件FloatFieldImageField????????#Inherits all attributes and methods from FileField, but also validates that the uploaded object is a valid image.IntegerFieldGenericIPAddressField?#IP地址，支持ipv4NullBooleanField??????#Like a BooleanField, but allows NULL as one of the optionsPositiveIntegerField??#Like an IntegerField, but must be either positive or zero (0). Values from 0 to 2147483647PositiveSmallIntegerField?#only allows positive? values from 0 to 32767SlugField?# A slug is a short label for something, containing only letters, numbers, underscores or hyphens.SmallIntegerFieldTextField???#A large text field.TimeField???#A time, represented in Python by a datetime.time instance.URLFieldUUIDField???#A field for storing universally unique identifiers. Uses Python’s UUID class. |
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除了普通的表字段，針對外鍵也有映射
| 1234 | ForeignKey??# 外鍵關(guān)聯(lián)ManyToManyField??#多對多?OneToOneField??# 1對1 |
好啦，接下來就用django的orm來設(shè)計(jì)一個(gè)博客表。
需求
根據(jù)需求，我們設(shè)計(jì)3張表
注意Article表和Tag表是屬于多對多關(guān)系，什么是多對多？即一個(gè)文章有多個(gè)標(biāo)簽，一個(gè)標(biāo)簽又可以屬于多個(gè)文章。?
比如上圖的Article表中id為3的文章 ，它的標(biāo)簽是4,26, 即投資、大文娛、社交， 你看“投資”這個(gè)標(biāo)簽同時(shí)還屬于文章2。 這就是多對多關(guān)系 ， 即many to many .?
那這種多對多的關(guān)系如何在表中存儲(chǔ)呢？難道真的像上圖中一樣，在Article表中加個(gè)tags字段，關(guān)聯(lián)Tag表里的多條數(shù)據(jù)，通過逗號(hào)區(qū)分？
這倒確實(shí)是個(gè)解決辦法。但是也有問題，一個(gè)字段里存多條紀(jì)錄的id,就沒辦法做查詢優(yōu)化了。比如不能做索引等。
所以若想實(shí)現(xiàn)多對多關(guān)系的高效存儲(chǔ) 查詢優(yōu)化，可以在Article and Tag表之間再搞出一張表。
這樣是不是就實(shí)現(xiàn)了多對多關(guān)聯(lián)？
yes, 沒錯(cuò)， django也是這么做的， django 有個(gè)專門的字段，叫ManyToManyField, 就是用來實(shí)現(xiàn)多對多關(guān)聯(lián)的，它會(huì)自動(dòng)生成一個(gè)如上圖一樣的第3張表來存儲(chǔ)多對多關(guān)系。
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| 123456789101112131415161718192021222324252627 | from?django.db?import?models?# Create your models here.??class?Account(models.Model):????username?=?models.CharField(max_length=64,unique=True)????email?=?models.EmailField()????password?=?models.CharField(max_length=128)????register_date?=?models.DateTimeField("注冊日期",auto_now_add=True)????signature?=?models.CharField(verbose_name="簽名",max_length=128,blank=True,null=True)??class?Article(models.Model):????"""文章表"""????title?=?models.CharField(max_length=255,unique=True)????content?=?models.TextField("文章內(nèi)容")????account?=?models.ForeignKey("Account",verbose_name="作者",on_delete=models.CASCADE)????tags?=?models.ManyToManyField("Tag",blank=True)????pub_date?=?models.DateTimeField()????read_count?=?models.IntegerField(default=0)??class?Tag(models.Model):????"""文章標(biāo)簽表"""????name?=?models.CharField(max_length=64,unique=True)????date?=?models.DateTimeField(auto_now_add=True) |
我們發(fā)現(xiàn)，每個(gè)字段其實(shí)都是一個(gè)獨(dú)立的對象，一張表其實(shí)是很多類的組合。
上面好多字段里還跟了些參數(shù)，我們來看以下常用的：
| 123456789101112131415 | null????????#If True, Django will store empty values as NULL in the database. Default is False.blank???????#If True, the field is allowed to be blank. Default is False.?db_column???#The name of the database column to use for this field. If this isn’t given, Django will use the field’s name.db_index????#If True, a database index will be created for this field.default?????#The default value for the field. This can be a value or a callable object. If callable it will be called every time a new object is created.editable????# django admin中用，后面講help_text???# django admin中用，后面講primary_key?# If True, this field is the primary key for the model.unique??????#If True, this field must be unique throughout the tableunique_for_date????#Set this to the name of a DateField or DateTimeField to require that this field be unique for the value of the date field. For example, if you have a field title that has unique_for_date="pub_date", then Django wouldn’t allow the entry of two records with the same title and pub_date.?unique_for_month???#Like unique_for_date, but requires the field to be unique with respect to the month.unique_for_year???verbose_name????#A human-readable name for the field. If the verbose name isn’t given, Django will automatically create it using the field’s attribute name |
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還有幾個(gè)特殊的字段屬性需要單獨(dú)介紹下
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choices
An iterable (e.g., a list or tuple) consisting itself of iterables of exactly two items (e.g. [(A, B), (A, B) ...]) to use as choices for this field.
The first element in each tuple is the actual value to be set on the model, and the second element is the human-readable name.
| 123456789101112 | class?Student(models.Model):????YEAR_IN_SCHOOL_CHOICES?=?(????????('FR',?'Freshman'),????????('SO',?'Sophomore'),????????('JR',?'Junior'),????????('SR',?'Senior'),????)????year_in_school?=?models.CharField(????????max_length=2,????????choices=YEAR_IN_SCHOOL_CHOICES,????????default=FRESHMAN,????) |
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ForeignKey.on_delete
當(dāng)一條記錄關(guān)聯(lián)的外鍵紀(jì)錄被刪除時(shí)，django 也會(huì)根據(jù)外鍵關(guān)聯(lián)限制的配置來決定如何處理當(dāng)前這條紀(jì)錄。舉例，如果你有個(gè)可以為null的外鍵關(guān)聯(lián),并且你想在本紀(jì)錄關(guān)聯(lián)的數(shù)據(jù)被刪除時(shí)，把當(dāng)前紀(jì)錄的關(guān)聯(lián)字段設(shè)為null,那就配置如下
| 123456 | user?=?models.ForeignKey(????User,????on_delete=models.SET_NULL,????blank=True,????null=True,) |
這個(gè)on_delete就是決定在關(guān)聯(lián)對象被刪除時(shí)，如何處理當(dāng)前紀(jì)錄的，常用的參數(shù)如下：
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Django支持多種數(shù)據(jù)庫，Sqlite、Mysql、Oracle、PostgreSQL，默認(rèn)的是小型文件數(shù)據(jù)庫Sqlite
| 123456 | DATABASES?=?{????'default': {????????'ENGINE':?'django.db.backends.sqlite3',????????'NAME': os.path.join(BASE_DIR,?'db.sqlite3'),????}} |
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咱們是干大事的人，怎么也得用個(gè)Mysql呀， 改成mysql 也so easy.
| 12345678910 | DATABASES?=?{????'default': {????????'ENGINE':?'django.db.backends.mysql',????????'NAME':?'my_db',????????'USER':?'mydatabaseuser',????????'PASSWORD':?'mypassword',????????'HOST':?'127.0.0.1',????????'PORT':?'3306',????}} |
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不過注意，python3 連接mysql的得使用pymysql,MysqlDB模塊300年沒更新了，但django默認(rèn)調(diào)用的還是MySQLdb, so pymysql有個(gè)功能可以讓django以為是用了MySQLdb. 即在項(xiàng)目目錄下的__init__.py中加上句代碼就好
| 123 | import?pymysql?pymysql.install_as_MySQLdb() |
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不加的話，一會(huì)連接數(shù)據(jù)時(shí)會(huì)報(bào)錯(cuò)噢 。
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你在ORM定義的表結(jié)構(gòu)如何同步到真實(shí)的數(shù)據(jù)庫里呢？ 只需2條命令。但django只能幫你自動(dòng)創(chuàng)建表，數(shù)據(jù)庫本身還是得你自己來。
| 1 | create?database?my_db charset utf8; |
好了，可以同步了，說好只需2步。
1. 生成同步文件,?django自帶一個(gè)專門的工具叫migrations, 負(fù)責(zé)把你的orm表轉(zhuǎn)成實(shí)際的表結(jié)構(gòu)，它不旦可以幫自動(dòng)創(chuàng)建表，對表結(jié)構(gòu)的修改，比如增刪改字段、改字段屬性等也都能自動(dòng)同步。只需通過下面神奇的命令。
| 1 | python manage.py makemigrations |
?不出意外的話，會(huì)顯示類似以下信息
| 1234567 | $ python manage.py makemigrationsMigrations?for?'app01':??app01/migrations/0001_initial.py????- Create model Account????- Create model Article????- Create model Tag????- Add field tags to article |
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此時(shí)你會(huì)發(fā)現(xiàn)，你的app下的migrations目錄里多了一個(gè)0001_initial.py的文件 ，這個(gè)文件就是因?yàn)槟氵@條命令而創(chuàng)建的，migrations工具就會(huì)根據(jù)這個(gè)文件來創(chuàng)建數(shù)據(jù)庫里的表。
2. 同步到數(shù)據(jù)
| 1234567891011121314151617181920 | $ python manage.py migrateOperations to perform:??Apply all migrations: admin, app01, auth, contenttypes, sessionsRunning migrations:??Applying contenttypes.0001_initial... OK??Applying auth.0001_initial... OK??Applying admin.0001_initial... OK??Applying admin.0002_logentry_remove_auto_add... OK??Applying app01.0001_initial... OK??Applying contenttypes.0002_remove_content_type_name... OK??Applying auth.0002_alter_permission_name_max_length... OK??Applying auth.0003_alter_user_email_max_length... OK??Applying auth.0004_alter_user_username_opts... OK??Applying auth.0005_alter_user_last_login_null... OK??Applying auth.0006_require_contenttypes_0002... OK??Applying auth.0007_alter_validators_add_error_messages... OK??Applying auth.0008_alter_user_username_max_length... OK??Applying auth.0009_alter_user_last_name_max_length... OK??Applying sessions.0001_initial... OK(venv_django2) Alexs-MacBook-Pro:mysite alex$ |
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此時(shí)登錄你的數(shù)據(jù)庫，會(huì)發(fā)現(xiàn)創(chuàng)建了好多張表
| 1234567891011121314151617181920 | mysql> show tables; ---------------------------- | Tables_in_luffy_dev2?????? | ---------------------------- | app01_account????????????? |??#對應(yīng)Account表| app01_article????????????? |??#對應(yīng)Article表| app01_article_tags???????? |??#自動(dòng)創(chuàng)建的Article to Tag的多對多關(guān)聯(lián)表| app01_tag????????????????? |??#對應(yīng)Tag表| auth_group???????????????? |??#下面這些，都是django 自帶的表，這個(gè)是自動(dòng)用戶系統(tǒng)的組| auth_group_permissions???? |??#自帶的組與權(quán)限的多對多關(guān)聯(lián)表| auth_permission??????????? |??#自帶權(quán)限表| auth_user????????????????? |??#用戶表| auth_user_groups?????????? || auth_user_user_permissions || django_admin_log?????????? |??#現(xiàn)在你的無法理解??| django_content_type??????? |??#現(xiàn)在你的無法理解| django_migrations????????? |??#紀(jì)錄migartions工具同步紀(jì)錄的表| django_session???????????? |??#現(xiàn)在你的無法理解 ---------------------------- 14 rows?in?set?(0.00 sec) |
好啦，表結(jié)構(gòu)也有了，我們可以往里面插數(shù)據(jù)啦。
之前說好的是可以不用SQL語句的，一點(diǎn)不騙你。
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先進(jìn)入已經(jīng)連接好數(shù)據(jù)庫的django python環(huán)境
| 1234567 | (venv_django2) Alexs-MacBook-Pro:mysite alex$ python manage.py shell?Python 3.5.2 (v3.5.2:4def2a2901a5, Jun 26 2016, 10:47:25)[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwinType?"help",?"copyright",?"credits"?or?"license"?for?more?information.(InteractiveConsole)>>>>>> from app01?import?models |
創(chuàng)建
創(chuàng)建數(shù)據(jù)簡單的令人發(fā)指
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查
filter 支持很多的過濾條件，我們來看下：
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contains
包含，相當(dāng)于sql的like條件
| 1 | Entry.objects.get(headline__contains='Lennon') |
SQL equivalent:
| 1 | SELECT?...?WHERE?headline?LIKE?'%Lennon%'; |
Note this will match the headline 'Lennon honored today' but not 'lennon honored today'.
icontains? 大小寫不敏感
in
In a given iterable; often a list, tuple, or queryset.
| 1 | Entry.objects.filter(id__in=[1,?3,?4]) |
SQL equivalent:
| 1 | SELECT?...?WHERE?id?IN?(1, 3, 4); |
You can also use a queryset to dynamically evaluate the list of values instead of providing a list of literal values:
| 12 | inner_qs?=?Blog.objects.filter(name__contains='Cheddar')entries?=?Entry.objects.filter(blog__in=inner_qs) |
This queryset will be evaluated as subselect statement:
| 1 | SELECT?...?WHERE?blog.id?IN?(SELECT?id?FROM?...?WHERE?NAME?LIKE?'%Cheddar%') |
gt
| 1 | Entry.objects.filter(id__gt=4) |
SQL equivalent:
| 1 | SELECT?...?WHERE?id > 4; |
gte
Greater than or equal to.
lt
Less than.
lte
Less than or equal to.
startswith
Case-sensitive starts-with.
| 1 | Entry.objects.filter(headline__startswith='Lennon') |
SQL equivalent:
| 1 | SELECT?...?WHERE?headline?LIKE?'Lennon%'; |
SQLite doesn’t support case-sensitive LIKE statements; startswith acts like istartswith for SQLite
istartswith
Case-insensitive starts-with.
endswith
Case-sensitive ends-with.
iendswith
Case-insensitive ends-with
range
區(qū)間過渡，可對數(shù)字、日期進(jìn)行過濾
| 1234 | import?datetimestart_date?=?datetime.date(2005,?1,?1)end_date?=?datetime.date(2005,?3,?31)Entry.objects.filter(pub_date__range=(start_date, end_date)) |
SQL equivalent:
| 1 | SELECT ... WHERE pub_date BETWEEN?'2005-01-01'?and?'2005-03-31'; |
Warning！
Filtering a DateTimeField with dates won’t include items on the last day, because the bounds are interpreted as “0am on the given date”. If pub_date was a DateTimeField, the above expression would be turned into this SQL:
SELECT ... WHERE pub_date BETWEEN '2005-01-01 00:00:00' and '2005-03-31 00:00:00';
Generally speaking, you can’t mix dates and datetimes.
date
For datetime fields, casts the value as date. Allows chaining additional field lookups. Takes a date value.
| 12 | Entry.objects.filter(pub_date__date=datetime.date(2005,?1,?1))Entry.objects.filter(pub_date__date__gt=datetime.date(2005,?1,?1)) |
year
For date and datetime fields, an exact year match. Allows chaining additional field lookups. Takes an integer year.
| 12 | Entry.objects.filter(pub_date__year=2005)Entry.objects.filter(pub_date__year__gte=2005) |
SQL equivalent:
| 12 | SELECT?...?WHERE?pub_date?BETWEEN?'2005-01-01'?AND?'2005-12-31';SELECT?...?WHERE?pub_date >=?'2005-01-01'; |
When USE_TZ is True, datetime fields are converted to the current time zone before filtering. 簡單解決辦法是把USE_TZ=False
month
For date and datetime fields, an exact month match. Allows chaining additional field lookups. Takes an integer 1 (January) through 12 (December).
| 12 | Entry.objects.filter(pub_date__month=12)Entry.objects.filter(pub_date__month__gte=6) |
When?USE_TZ?is?True, datetime fields are converted to the current time zone before filtering. This requires?time zone definitions in the database.
SQL equivalent:
| 12 | SELECT?...?WHERE?EXTRACT('month'?FROM?pub_date) =?'12';SELECT?...?WHERE?EXTRACT('month'?FROM?pub_date) >=?'6'; |
day
For date and datetime fields, an exact day match. Allows chaining additional field lookups. Takes an integer day.
| 12 | Entry.objects.filter(pub_date__day=3)Entry.objects.filter(pub_date__day__gte=3) |
SQL equivalent:
| 12 | SELECT?...?WHERE?EXTRACT('day'?FROM?pub_date) =?'3';SELECT?...?WHERE?EXTRACT('day'?FROM?pub_date) >=?'3'; |
weekFor date and datetime fields, return the week number (1-52 or 53) according to?ISO-8601, i.e., weeks start on a Monday and the first week contains the year’s first Thursday.
Example:
| 12 | Entry.objects.filter(pub_date__week=52)Entry.objects.filter(pub_date__week__gte=32, pub_date__week__lte=38) |
week_dayFor date and datetime fields, a ‘day of the week’ match. Allows chaining additional field lookups.
Takes an integer value representing the day of week from 1 (Sunday) to 7 (Saturday).
Example:
| 12 | Entry.objects.filter(pub_date__week_day=2)Entry.objects.filter(pub_date__week_day__gte=2) |
hourFor datetime and time fields, an exact hour match. Allows chaining additional field lookups. Takes an integer between 0 and 23.
Example:
| 123 | Event.objects.filter(timestamp__hour=23)Event.objects.filter(time__hour=5)Event.objects.filter(timestamp__hour__gte=12) |
SQL equivalent:
| 123 | SELECT?...?WHERE?EXTRACT('hour'?FROM?timestamp) =?'23';SELECT?...?WHERE?EXTRACT('hour'?FROM?time) =?'5';SELECT?...?WHERE?EXTRACT('hour'?FROM?timestamp) >=?'12';同 |
同時(shí)，還支持mintue,second
| 1234 | Event.objects.filter(time__minute=46)??Event.objects.filter(timestamp__second=31) |
isnullTakes either?True?or?False, which correspond to SQL queries of?IS?NULL?and?IS?NOT?NULL, respectively.
Example:
| 1 | Entry.objects.filter(pub_date__isnull=True) |
SQL equivalent:
| 1 | SELECT?...?WHERE?pub_date?IS?NULL; |
regexCase-sensitive regular expression match.
Example:
| 1 | Entry.objects.get(title__regex=r'^(An?|The) ') |
SQL equivalents:
| 1234567 | SELECT?...?WHERE?title REGEXP?BINARY?'^(An?|The) ';?-- MySQL?SELECT?...?WHERE?REGEXP_LIKE(title,?'^(An?|The) ',?'c');?-- Oracle?SELECT?...?WHERE?title ~?'^(An?|The) ';?-- PostgreSQL?SELECT?...?WHERE?title REGEXP?'^(An?|The) ';?-- SQLite |
iregex?大小寫不敏感
改刪
| 123456789101112131415 | # 批量修改models.Account.objects.filter(username='elina').update(password="Luffy#21")?# 單條修改obj?=?models.Account.objects.get(username='linux')obj.username?=?'python'obj.save()??# 批量刪除models.User.objects.get(password='oldboy').delete()?# 單條刪除obj?=?models.User.objects.get(id=3)obj.delete() |
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values()Returns a?QuerySet?that returns dictionaries, rather than model instances, when used as an iterable.
| 1234 | >>> Blog.objects.values()<QuerySet [{'id':?1,?'name':?'Beatles Blog',?'tagline':?'All the latest Beatles news.'}]>>>> Blog.objects.values('id',?'name')<QuerySet [{'id':?1,?'name':?'Beatles Blog'}]> |
order_by()By default, results returned by a?QuerySet?are ordered by the ordering tuple given by the?ordering?option in the model’s?Meta. You can override this on a per-QuerySet?basis by using the?order_by?method.
| 1 | Entry.objects.filter(pub_date__year=2005).order_by('-pub_date',?'headline') |
The result above will be ordered by?pub_date?descending, then by?headline?ascending. The negative sign in front of?"-pub_date"indicates?descending?order. Ascending order is implied.?
reverse()Use the?reverse()?method to reverse the order in which a queryset’s elements are returned. Calling?reverse()?a second time restores the ordering back to the normal direction.
To retrieve the “l(fā)ast” five items in a queryset, you could do this:
| 1 | my_queryset.reverse()[:5] |
| 123456789101112131415161718192021222324252627 | 單表對象操作o?=?models.Article.objects.all()[0]o.tilte?外鍵關(guān)聯(lián)>>> o.account.username'jack'>>> o.account.username?=?rain?外鍵反向關(guān)聯(lián)操作>>> a?=?models.Account.objects.get(username='alex')>>> a.article_set.all()<QuerySet [<Article: 你好，2018>]>>>> a.article_set.select_related()<QuerySet [<Article: 你好，2018>]>??多對多操作>>> o?=?models.Article.objects.all()[1]>>> o.tags.all()<QuerySet [<Tag: 投資>, <Tag: 科技>]>??多對多反向操作>>> t?=?models.Tag.objects.get(name="投資")>>> t.article_set.all()<QuerySet [<Article: 你好，2018>, <Article: 粉絲超過10萬后，我經(jīng)歷了抖音盜號(hào)風(fēng)波>]> |
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好啦，orm的操作先點(diǎn)到為止，后面學(xué)項(xiàng)目時(shí)再帶你搞復(fù)雜的。
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來源：https://www.icode9.com/content-4-328551.html
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