{"id":316083,"date":"2021-02-04T10:11:41","date_gmt":"2021-02-04T02:11:41","guid":{"rendered":"http:\/\/4563.org\/?p=316083"},"modified":"2021-02-04T10:11:41","modified_gmt":"2021-02-04T02:11:41","slug":"django-%e6%9b%b4%e6%96%b0%e4%b8%80%e6%9d%a1%e5%8f%af%e8%83%bd%e4%b8%8d%e5%ad%98%e5%9c%a8%e7%9a%84%e7%89%b9%e5%ae%9a%e6%95%b0%e6%8d%ae%e6%98%af-get-%e6%80%a7%e8%83%bd%e5%a5%bd%e8%bf%98%e6%98%af-filter","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=316083","title":{"rendered":"Django \u66f4\u65b0\u4e00\u6761\u53ef\u80fd\u4e0d\u5b58\u5728\u7684\u7279\u5b9a\u6570\u636e\u662f Get \u6027\u80fd\u597d\u8fd8\u662f Filter \u597d"},"content":{"rendered":"
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Django \u66f4\u65b0\u4e00\u6761\u53ef\u80fd\u4e0d\u5b58\u5728\u7684\u7279\u5b9a\u6570\u636e\u662f Get \u6027\u80fd\u597d\u8fd8\u662f Filter \u597d <\/h1>\n

<\/p>\n

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\u8cc7\u6df1\u5927\u4f6c : Phishion <\/span> <\/i> 6<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
<\/p>\n

\u6211\u60f3\u4f18\u5316\u4e00\u4e0b\u6027\u80fd\uff0c\u4f46\u662f\u6709\u4e00\u4e2a\u5730\u65b9\u6709 2 \u79cd\u5199\u6cd5\uff0c\u6211\u4e0d\u77e5\u9053\u54ea\u79cd\u597d\u4e00\u70b9\uff0c\u5c31\u662f\u6bd4\u5982\u6709\u6761\u6570\u636e\u8fdb\u6765\uff0c\u6211\u8981\u5148\u5224\u65ad\u8fd9\u6761\u6570\u636e\u5728\u4e0d\u5728\uff0c\u5982\u679c\u5728\u5c31\u66f4\u65b0\uff0c\u4e0d\u5728\u5c31\u76f4\u63a5\u65b0\u5efa\u4e00\u6761<\/p>\n

\u4f2a\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n

\u65b9\u6cd5 1 \uff09<\/p>\n

try:     article = Article.objects.get(id=9999)     \u89e6\u53d1\uff1a\u66f4\u65b0\u903b\u8f91 except:     \u89e6\u53d1\uff1a\u65b0\u5efa\u903b\u8f91 <\/code><\/pre>\n
\u65b9\u6cd5 2 \uff09<\/p>\n
article = Article.objects.filter(id=9999) if article.exists():     exist_article = article[0]     \u89e6\u53d1\uff1a\u66f4\u65b0\u903b\u8f91 else:     \u89e6\u53d1\uff1a\u65b0\u5efa\u903b\u8f91 <\/code><\/pre>\n
\u611f\u89c9\u65b9\u6cd5 1 \u6709\u70b9\u5947\u602a\uff0c\u4f46\u662f\u4f3c\u4e4e\u5c31\u8bbf\u95ee\u4e00\u6b21\u6570\u636e\u5e93\uff0c\u65b9\u6cd5\u4e8c\u5570\u55e6\u4e00\u70b9\uff0c\u4e0d\u77e5\u9053\u6709\u6ca1\u6709\u8001\u9e1f\u80fd\u63d0\u4f9b\u5e2e\u52a9\uff1f<\/p>\n<\/p><\/div>\n
 \u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (19<\/span>)        <\/div>\n
 <\/div>\n<\/p><\/div>\n<\/p><\/div>\n
    \n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : wuwukai007 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 get_or_create                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : youngce <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 Article.objects.update_or_create() \uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : Phishion <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @wuwukai007 \u8bf7\u95ee\uff0c\u8fd9\u79cd\u5206\u88c5\u597d\u7684\u5e95\u5c42\u53c8\u662f\u600e\u4e48\u5b9e\u73b0\u7684\u5462\uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : renmu123 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 1 \u6bd4\u8f83\u7b26\u5408 Python \u54f2\u5b66                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : Phishion <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @wuwukai007 
    \u6211\u770b\u5b83\u6587\u6863\u91cc\u9762\u8fd8\u771f\u662f try \u51fa\u6765\u7684\uff0c\u771f\u539f\u59cb\u554a                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : zeroDev <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u5e94\u8be5\u7528 try except \u7ed3\u6784\uff0c\u907f\u514d\u5224\u65ad
    \u53c2\u8003 Python \u5b98\u65b9\u6587\u6863 https:\/\/docs.python.org\/3.6\/glossary.html#term-eafp                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : zeroDev <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @Phishion try \u5c31\u907f\u514d\u4e86\u5f88\u591a\u6761\u4ef6\u5224\u65ad\uff0c\u5199 Python \u672c\u8eab\u5c31\u662f\u4e3a\u4e86\u5feb\u901f\u5f00\u53d1\u561b                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : Phishion <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @zeroDev \u597d\u7684 \u6211\u77a7\u77a7                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : Phishion <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @zeroDev \u6211\u4e00\u76f4\u6f5c\u610f\u8bc6\u8ba4\u4e3a\u62a5\u9519\u4f1a\u6709\u989d\u5916\u7684\u6027\u80fd\u5f00\u9500\uff0c\u6240\u4ee5\u5c31\u611f\u89c9\u7528 try \u5904\u7406\u6b63\u5e38\u4e1a\u52a1\u903b\u8f91\u5f88\u5947\u602a                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : wuwukai007 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4f60\u53ef\u4ee5\u8fd9\u6837\u7406\u89e3\uff0c\u5982\u679c\u5b58\u5728\u7684\u53ef\u80fd\u65b0\u8fdc\u8fdc\u5927\u4e8e \u4e0d\u5b58\u5728\uff0c\u90a3\u4e48\u4f7f\u7528 try \u7684\u6027\u80fd\u4e0d\u5c31\u4f1a\u641e\u7684\u591a\u5417\uff0c\u4e0d\u7528 try\uff0c\u6bcf\u6b21\u90fd\u8981\u5224\u65ad                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : Phishion <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @wuwukai007 \u6709\u9053\u7406\uff0c\u8c22\u8c22\uff01                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : Geek981108 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u6587\u6863\u5982\u662f\u8bf4\uff1a
    update_or_create()
    update_or_create(defaults=None, **kwargs)
    A convenience method for updating an object with the given kwargs, creating a new one if necessary. The defaults is a dictionary of (field, value) pairs used to update the object. The values in defaults can be callables.<\/p>\n
    Returns a tuple of (object, created), where object is the created or updated object and created is a boolean specifying whether a new object was created.<\/p>\n
    The update_or_create method tries to fetch an object from database based on the given kwargs. If a match is found, it updates the fields passed in the defaults dictionary.<\/p>\n
    This is meant as a shortcut to boilerplatish code. For example:<\/p>\n
    defaults = {‘first_name’: ‘Bob’}
    try:
     obj = Person.objects.get(first_name=’John’, last_name=’Lennon’)
     for key, value in defaults.items():
     setattr(obj, key, value)
     obj.save()
    except Person.DoesNotExist:
     new_values = {‘first_name’: ‘John’, ‘last_name’: ‘Lennon’}
     new_values.update(defaults)
     obj = Person(**new_values)
     obj.save()
    This pattern gets quite unwieldy as the number of fields in a model goes up. The above example can be rewritten using update_or_create() like so:<\/p>\n
    obj, created = Person.objects.update_or_create(
     first_name=’John’, last_name=’Lennon’,
     defaults={‘first_name’: ‘Bob’},
    )
    For detailed description how names passed in kwargs are resolved see get_or_create().<\/p>\n
    As described above in get_or_create(), this method is prone to a race-condition which can result in multiple rows being inserted simultaneously if uniqueness is not enforced at the database level.<\/p>\n
    Like get_or_create() and create(), if you\u2019re using manually specified primary keys and an object needs to be created but the key already exists in the database, an IntegrityError is raised.                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : lixuda <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u6211\u7528\u8fd9\u6837,\u4e0d\u77e5\u9053\u6027\u80fd\u597d\u4e0d\u597d
    article = Article.objects.filter(id=9999).first()
    if(article):                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : Phishion <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @lixuda \u6211\u89c9\u5f97\u7528\u5b83\u5c01\u88c5\u597d\u7684\u6027\u80fd\u6700\u597d\uff0c\u5224\u65ad\u592a\u591a\u4ee3\u7801\u4e5f\u663e\u5f97\u4e0d\u6574\u6d01                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : lixuda <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @Phishion \u770b\u9519\u4e86\uff0c\u662f\u66f4\u65b0\u903b\u8f91\uff0cupdate_or_create                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : Austaras <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u6709\u7684\u6570\u636e\u5e93\u652f\u6301 upsert                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : chaleaoch <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4f60\u770b\u6e90\u7801,\u5176\u5b9e\u8fd9\u4fe9\u903b\u8f91\u5dee\u4e0d\u591a. get \u91cc\u9762\u5c31\u662f filter + try catch                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : nonduality <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4f60\u7684\u65b9\u6cd5 2 \u4f1a\u5f15\u53d1\u4e24\u6b21\u67e5\u8be2\uff0c\u4f18\u5316\u6587\u6863\u7ecf\u5e38\u63d0\u5230\u4e0d\u8981\u6ee5\u7528 exists()\uff1a\u5982\u679c\u540e\u7eed\u4ecd\u9700\u8981\u4f7f\u7528\u5230\u5bf9\u8c61\u6570\u636e\uff0c\u5c31\u65e0\u987b\u7528 exists()\u53bb\u5224\u65ad\u5bf9\u8c61\u5b58\u5728\u4e0e\u5426\u3002<\/p>\n
    \u7528 #13 \u7684\u65b9\u6cd5\u4e5f\u53ef\u4ee5\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : Phishion <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @nonduality 
    @chaleaoch
    @lixuda
    \u611f\u8c22\u63d0\u4f9b\u6307\u5bfc\uff01                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n","protected":false},"excerpt":{"rendered":"
    Django \u66f4\u65b0\u4e00\u6761\u53ef\u80fd\u4e0d\u5b58\u5728\u7684…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/316083"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=316083"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/316083\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=316083"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=316083"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=316083"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}