{"id":1705,"date":"2021-08-02T15:24:59","date_gmt":"2021-08-02T07:24:59","guid":{"rendered":"https:\/\/egonlin.com\/?p=1705"},"modified":"2022-02-07T17:45:34","modified_gmt":"2022-02-07T09:45:34","slug":"django%e6%a1%86%e6%9e%b6","status":"publish","type":"post","link":"https:\/\/egonlin.com\/?p=1705","title":{"rendered":"Django\u6846\u67b6"},"content":{"rendered":"
1. Django ORM\u67e5\u8be2\u4e2dselect_related\u548cprefetch_related\u7684\u533a\u522b\uff1f\uff1f<\/h5>\n
def select_related(self, *fields)\n    \u6027\u80fd\u76f8\u5173\uff1a\u8868\u4e4b\u95f4\u8fdb\u884cjoin\u8fde\u8868\u64cd\u4f5c\uff0c\u4e00\u6b21\u6027\u83b7\u53d6\u5173\u8054\u7684\u6570\u636e\u3002\n\n    \u603b\u7ed3\uff1a\n    1. select_related\u4e3b\u8981\u9488\u4e00\u5bf9\u4e00\u548c\u591a\u5bf9\u4e00\u5173\u7cfb\u8fdb\u884c\u4f18\u5316\u3002\n    2. select_related\u4f7f\u7528SQL\u7684JOIN\u8bed\u53e5\u8fdb\u884c\u4f18\u5316\uff0c\u901a\u8fc7\u51cf\u5c11SQL\u67e5\u8be2\u7684\u6b21\u6570\u6765\u8fdb\u884c\u4f18\u5316\u3001\u63d0\u9ad8\u6027\u80fd\u3002\n\ndef prefetch_related(self, *lookups)\n    \u6027\u80fd\u76f8\u5173\uff1a\u591a\u8868\u8fde\u8868\u64cd\u4f5c\u65f6\u901f\u5ea6\u4f1a\u6162\uff0c\u4f7f\u7528\u5176\u6267\u884c\u591a\u6b21SQL\u67e5\u8be2\u5728Python\u4ee3\u7801\u4e2d\u5b9e\u73b0\u8fde\u8868\u64cd\u4f5c\u3002\n\n    \u603b\u7ed3\uff1a\n    1. \u5bf9\u4e8e\u591a\u5bf9\u591a\u5b57\u6bb5\uff08ManyToManyField\uff09\u548c\u4e00\u5bf9\u591a\u5b57\u6bb5\uff0c\u53ef\u4ee5\u4f7f\u7528prefetch_related()\u6765\u8fdb\u884c\u4f18\u5316\u3002\n    2. prefetch_related()\u7684\u4f18\u5316\u65b9\u5f0f\u662f\u5206\u522b\u67e5\u8be2\u6bcf\u4e2a\u8868\uff0c\u7136\u540e\u7528Python\u5904\u7406\u4ed6\u4eec\u4e4b\u95f4\u7684\u5173\u7cfb\u3002<\/code><\/pre>\n
2. Django ORM\u662f\u4ec0\u4e48\uff1f<\/h5>\n
\u5bf9\u8c61\u5173\u7cfb\u6620\u5c04\uff0c\u901a\u8fc7models\u4e2d\u7684\u7c7b\u6765\u5bf9\u5e94\u6570\u636e\u5e93\u4e2d\u7684\u4e00\u4e2a\u8868\uff0c\u4e00\u4e2a\u5bf9\u8c61\u5bf9\u5e94\u4e00\u4e2a\u6570\u636e\u884c\uff0c\u4e00\u4e2a\u5c5e\u6027\u5bf9\u5e94\u6570\u636e\u5e93\u4e2d\u7684\u4e00\u4e2a\u5b57\u6bb5<\/code><\/pre>\n
\"\u5bf9\u8c61\u5173\u7cfb\u6620\u5c04\"<\/div><\/p>\n
3. Django\u521b\u5efa\u9879\u76ee\u7684\u547d\u4ee4\uff1f<\/h5>\n
django-admin startproject \u9879\u76ee\u540d\u79f0
\npython manage.py startapp \u5e94\u7528 app \u540d <\/p>\n
4. Django \u521b\u5efa\u9879\u76ee\u540e\uff0c\u9879\u76ee\u6587\u4ef6\u5939\u4e0b\u7684\u7ec4\u6210\u90e8\u5206\uff08\u5bf9mvt \u7684\u7406\u89e3\uff09\uff1f<\/h5>\n
\u9879\u76ee\u6587\u4ef6\u5939\u4e0b\u7684\u7ec4\u6210\u90e8\u5206\uff1a
\nmanage.py \u662f\u9879\u76ee\u8fd0\u884c\u7684\u5165\u53e3\uff0c\u6307\u5b9a\u914d\u7f6e\u6587\u4ef6\u8def\u5f84\u3002
\n\u4e0e\u9879\u76ee\u540c\u540d\u7684\u76ee\u5f55\uff0c\u5305\u542b\u9879\u76ee\u7684\u914d\u7f6e\u6587\u4ef6\u3002
\n__init__<\/code>.py \u662f\u4e00\u4e2a\u7a7a\u6587\u4ef6\uff0c\u4f5c\u7528\u662f\u8fd9\u4e2a\u76ee\u5f55\u53ef\u4ee5\u88ab\u5f53\u4f5c\u5305\u4f7f\u7528,\u4e5f\u53ef\u4ee5\u505a\u4e00\u4e9b\u521d\u59cb\u5316\u64cd\u4f5c\u3002
\nsettings.py \u662f\u9879\u76ee\u7684\u6574\u4f53\u914d\u7f6e\u6587\u4ef6\u3002
\nurls.py \u662f\u9879\u76ee\u7684 URL \u914d\u7f6e\u6587\u4ef6\u3002
\nwsgi.py \u662f\u9879\u76ee\u4e0e WSGI \u517c\u5bb9\u7684 Web \u670d\u52a1\u5668\u3002 <\/p>\n
5. \u5bf9 MVC,MVT\u89e3\u8bfb\u7684\u7406\u89e3\uff1f<\/h5>\n
M\uff1aModel\uff0c\u6a21\u578b\uff0c\u548c\u6570\u636e\u5e93\u8fdb\u884c\u4ea4\u4e92
\nV\uff1aView\uff0c\u89c6\u56fe\uff0c\u8d1f\u8d23\u4ea7\u751fHtml\u9875\u9762
\nC\uff1aController\uff0c\u63a7\u5236\u5668\uff0c\u63a5\u6536\u8bf7\u6c42\uff0c\u8fdb\u884c\u5904\u7406\uff0c\u4e0eM\u548cV\u8fdb\u884c\u4ea4\u4e92\uff0c\u8fd4\u56de\u5e94\u7b54\u3002
\n
\"\"<\/div>
\n1\u3001 \u7528\u6237\u70b9\u51fb\u6ce8\u6309\u94ae\uff0c\u5c06\u8981\u6ce8\u518c\u7684\u4fe1\u606f\u53d1\u9001\u7ed9\u7f51\u7ad9\u670d\u52a1\u5668\u3002
\n2\u3001 Controller\u63a7\u5236\u5668\u63a5\u6536\u5230\u7528\u6237\u7684\u6ce8\u518c\u4fe1\u606f\uff0cController\u4f1a\u544a\u8bc9Model\u5c42\u5c06\u7528\u6237\u7684\u6ce8\u518c\u4fe1\u606f\u4fdd\u5b58\u5230\u6570\u636e\u5e93
\n3\u3001 Model\u5c42\u5c06\u7528\u6237\u7684\u6ce8\u518c\u4fe1\u606f\u4fdd\u5b58\u5230\u6570\u636e\u5e93
\n4\u3001 \u6570\u636e\u4fdd\u5b58\u4e4b\u540e\u5c06\u4fdd\u5b58\u7684\u7ed3\u679c\u8fd4\u56de\u7ed9Model\u6a21\u578b\uff0c
\n5\u3001 Model\u5c42\u5c06\u4fdd\u5b58\u7684\u7ed3\u679c\u8fd4\u56de\u7ed9Controller\u63a7\u5236\u5668\u3002
\n6\u3001 Controller\u63a7\u5236\u5668\u6536\u5230\u4fdd\u5b58\u7684\u7ed3\u679c\u4e4b\u540e\uff0c\u6216\u544a\u8bc9View\u89c6\u56fe\uff0cview\u89c6\u56fe\u4ea7\u751f\u4e00\u4e2ahtml\u9875\u9762\u3002
\n7\u3001 View\u5c06\u4ea7\u751f\u7684Html\u9875\u9762\u7684\u5185\u5bb9\u7ed9\u4e86Controller\u63a7\u5236\u5668\u3002
\n8\u3001 Controller\u5c06Html\u9875\u9762\u7684\u5185\u5bb9\u8fd4\u56de\u7ed9\u6d4f\u89c8\u5668\u3002
\n9\u3001 \u6d4f\u89c8\u5668\u63a5\u53d7\u5230\u670d\u52a1\u5668Controller\u8fd4\u56de\u7684Html\u9875\u9762\u8fdb\u884c\u89e3\u6790\u5c55\u793a\u3002
\nM\uff1aModel\uff0c\u6a21\u578b\uff0c\u548cMVC\u4e2d\u7684M\u529f\u80fd\u76f8\u540c\uff0c\u548c\u6570\u636e\u5e93\u8fdb\u884c\u4ea4\u4e92\u3002
\nV\uff1aview\uff0c\u89c6\u56fe\uff0c\u548cMVC\u4e2d\u7684C\u529f\u80fd\u76f8\u540c\uff0c\u63a5\u6536\u8bf7\u6c42\uff0c\u8fdb\u884c\u5904\u7406\uff0c\u4e0eM\u548cT\u8fdb\u884c\u4ea4\u4e92\uff0c\u8fd4\u56de\u5e94\u7b54\u3002
\nT\uff1aTemplate\uff0c\u6a21\u677f\uff0c\u548cMVC\u4e2d\u7684V\u529f\u80fd\u76f8\u540c\uff0c\u4ea7\u751fHtml\u9875\u9762
\n
\"\"<\/div>
\n1\u3001 \u7528\u6237\u70b9\u51fb\u6ce8\u518c\u6309\u94ae\uff0c\u5c06\u8981\u6ce8\u518c\u7684\u5185\u5bb9\u53d1\u9001\u7ed9\u7f51\u7ad9\u7684\u670d\u52a1\u5668\u3002
\n2\u3001 View\u89c6\u56fe\uff0c\u63a5\u6536\u5230\u7528\u6237\u53d1\u6765\u7684\u6ce8\u518c\u6570\u636e\uff0cView\u544a\u8bc9Model\u5c06\u7528\u6237\u7684\u6ce8\u518c\u4fe1\u606f\u4fdd\u5b58\u8fdb\u6570\u636e\u5e93\u3002
\n3\u3001 Model\u5c42\u5c06\u7528\u6237\u7684\u6ce8\u518c\u4fe1\u606f\u4fdd\u5b58\u5230\u6570\u636e\u5e93\u4e2d\u3002
\n4\u3001 \u6570\u636e\u5e93\u5c06\u4fdd\u5b58\u7684\u7ed3\u679c\u8fd4\u56de\u7ed9Model
\n5\u3001 Model\u5c06\u4fdd\u5b58\u7684\u7ed3\u679c\u7ed9View\u89c6\u56fe\u3002
\n6\u3001 View\u89c6\u56fe\u544a\u8bc9Template\u6a21\u677f\u53bb\u4ea7\u751f\u4e00\u4e2aHtml\u9875\u9762\u3002
\n7\u3001 Template\u751f\u6210html\u5185\u5bb9\u8fd4\u56de\u7ed9View\u89c6\u56fe\u3002
\n8\u3001 View\u5c06html\u9875\u9762\u5185\u5bb9\u8fd4\u56de\u7ed9\u6d4f\u89c8\u5668\u3002
\n9\u3001 \u6d4f\u89c8\u5668\u62ff\u5230view\u8fd4\u56de\u7684html\u9875\u9762\u5185\u5bb9\u8fdb\u884c\u89e3\u6790\uff0c\u5c55\u793a\u3002 <\/p>\n
6. Django\u4e2dmodels\u5229\u7528ORM\u5bf9Mysql\u8fdb\u884c\u67e5\u8868\u7684\u8bed\u53e5\uff08\u591a\u4e2a\u8bed\u53e5\uff09\uff1f<\/h5>\n
\u5b57\u6bb5\u67e5\u8be2
\nall():\u8fd4\u56de\u6a21\u578b\u7c7b\u5bf9\u5e94\u8868\u683c\u4e2d\u7684\u6240\u6709\u6570\u636e\u3002
\nget():\u8fd4\u56de\u8868\u683c\u4e2d\u6ee1\u8db3\u6761\u4ef6\u7684\u4e00\u6761\u6570\u636e\uff0c\u5982\u679c\u67e5\u5230\u591a\u6761\u6570\u636e\uff0c\u5219\u629b\u5f02\u5e38\uff1aMultipleObjectsReturned\uff0c
\n\u67e5\u8be2\u4e0d\u5230\u6570\u636e\uff0c\u5219\u629b\u5f02\u5e38\uff1aDoesNotExist\u3002
\nfilter():\u53c2\u6570\u5199\u67e5\u8be2\u6761\u4ef6\uff0c\u8fd4\u56de\u6ee1\u8db3\u6761\u4ef6 QuerySet \u96c6\u5408\u6570\u636e\u3002
\n\u6761\u4ef6\u683c\u5f0f\uff1a
\n\u6a21\u578b\u7c7b\u5c5e\u6027\u540d<\/strong>__\u6761\u4ef6\u540d=\u503c
\n\u6ce8\u610f\uff1a\u6b64\u5904\u662f\u6a21\u578b\u7c7b\u5c5e\u6027\u540d\uff0c\u4e0d\u662f\u8868\u4e2d\u7684\u5b57\u6bb5\u540d
\n\u5173\u4e8e filter \u5177\u4f53\u6848\u4f8b\u5982\u4e0b\uff1a
\n\u5224\u7b49 exact\u3002  <\/p>\n
 BookInfo.object.filter(id=1) \n BookInfo.object.filter(id__exact=1)\u6b64\u5904\u7684__exact \u53ef\u4ee5\u7701\u7565 <\/code><\/pre>\n
\u6a21\u7cca\u67e5\u8be2 like
\n\u4f8b\uff1a\u67e5\u8be2\u4e66\u540d\u5305\u542b’\u4f20’\u7684\u56fe\u4e66\u3002contains <\/p>\n
1. contains BookInfo.objects.filter(btitle__contains=\u2019\u4f20\u2019) <\/code><\/pre>\n
\u7a7a\u67e5\u8be2 where \u5b57\u6bb5\u540d isnull  <\/p>\n
1. BookInfo.objects.filter(btitle__isnull=False) <\/code><\/pre>\n
\u8303\u56f4\u67e5\u8be2 where id in (1\uff0c3\uff0c5)  <\/p>\n
1. BookInfo.objects.filter(id__in=[1\uff0c3\uff0c5]) <\/code><\/pre>\n
\u6bd4\u8f83\u67e5\u8be2 gt lt(less than) gte(equal) lte   <\/p>\n
1. BookInfo.objects.filter(id__gte=3) <\/code><\/pre>\n
\u65e5\u671f\u67e5\u8be2  <\/p>\n
1. BookInfo.objects.filter(bpub_date__year = 1980)  \n2. BookInfo.objects.filter(bpub_date__gt = date(1980\uff0c1\uff0c1)) <\/code><\/pre>\n
exclude:\u8fd4\u56de\u4e0d\u6ee1\u8db3\u6761\u4ef6\u7684\u6570\u636e\u3002  <\/p>\n
3. BookInfo.objects.exclude(id=3) <\/code><\/pre>\n
F \u5bf9\u8c61<\/strong>
\n\u4f5c\u7528\uff1a\u7528\u4e8e\u7c7b\u5c5e\u6027\u4e4b\u95f4\u7684\u6bd4\u8f83\u6761\u4ef6\u3002 <\/p>\n
1. from django.db.models import F \n2. \u4f8b\uff1awhere bread > bcomment BookInfo.objects.filter(bread__gt =F(\u2018bcomment\u2019)) \n3. \u4f8b\uff1aBookInfo.objects.filter(bread__gt=F(\u2018bcomment\u2019)*2) <\/code><\/pre>\n
Q \u5bf9\u8c61<\/strong>
\n\u4f5c\u7528\uff1a\u7528\u4e8e\u67e5\u8be2\u65f6\u7684\u903b\u8f91\u6761\u4ef6\u3002\u53ef\u4ee5\u5bf9 Q \u5bf9\u8c61\u8fdb\u884c&|~\u64cd\u4f5c\u3002 <\/p>\n
1. from django.db.models import Q  \n2. BookInfo.objects.filter(id__gt=3\uff0c bread__gt=30) \n3. BooInfo.objects.filter(Q(id__gt=3) & Q(bread__gt=3)) \n4. \u4f8b\uff1aBookInfo.objects.filter(Q(id__gt=3) | Q(bread__gt=30)) \n5. \u4f8b\uff1aBookInfo.objects.filter(~Q(id=3)) <\/code><\/pre>\n
order_by \u8fd4\u56de QuerySet
\n\u4f5c\u7528\uff1a\u5bf9\u67e5\u8be2\u7ed3\u679c\u8fdb\u884c\u6392\u5e8f\u3002 <\/p>\n
1. \u4f8b\uff1a BookInfo.objects.all().order_by('id') \n2. \u4f8b\uff1a BookInfo.objects.all().order_by('-id') \n3. \u4f8b\uff1aBookInfo.objects.filter(id__gt=3).order_by('-bread') <\/code><\/pre>\n
\u805a\u5408\u51fd\u6570<\/strong>
\n\u4f5c\u7528\uff1a\u5bf9\u67e5\u8be2\u7ed3\u679c\u8fdb\u884c\u805a\u5408\u64cd\u4f5c\u3002 <\/p>\n
1. sum count max min avg <\/code><\/pre>\n
aggregate\uff1a\u8c03\u7528\u8fd9\u4e2a\u51fd\u6570\u6765\u4f7f\u7528\u805a\u5408\u3002 <\/p>\n
1. from django.db.models import Sum\uff0cCount\uff0cMax\uff0cMin\uff0cAvg \n2. \u4f8b\uff1aBookInfo.objects.aggregate(Count('id')) <\/code><\/pre>\n
{‘id__count’: 5} \u6ce8\u610f\u8fd4\u56de\u503c\u7c7b\u578b\u53ca\u952e\u540d <\/p>\n
1. \u4f8b\uff1aBookInfo.objects.aggregate(Sum(\u2018bread\u2019)) <\/code><\/pre>\n
{\u2018bread__sum\u2019:120} \u6ce8\u610f\u8fd4\u56de\u503c\u7c7b\u578b\u53ca\u952e\u540d
\ncount \u51fd\u6570
\n\u4f5c\u7528\uff1a\u7edf\u8ba1\u6ee1\u8db3\u6761\u4ef6\u6570\u636e\u7684\u6570\u76ee\u3002
\n\u4f8b\uff1a\u7edf\u8ba1\u6240\u6709\u56fe\u4e66\u7684\u6570\u76ee\u3002 <\/p>\n
1. BookInfo.objects.all().count() <\/code><\/pre>\n
\u4f8b\uff1a\u7edf\u8ba1 id \u5927\u4e8e 3 \u7684\u6240\u6709\u56fe\u4e66\u7684\u6570\u76ee\u3002 <\/p>\n
1. BookInfo.objects.filter(id__gt = 3).count() <\/code><\/pre>\n
\u6a21\u578b\u7c7b\u5173\u7cfb<\/h5>\n
\u4e00\u5bf9\u591a\u5173\u7cfb<\/strong>
\n\u4f8b\uff1a\u56fe\u4e66\u7c7b-\u82f1\u96c4\u7c7b
\nmodels.ForeignKey() \u5b9a\u4e49\u5728\u591a\u7684\u7c7b\u4e2d\u3002
\n2\uff09\u591a\u5bf9\u591a\u5173\u7cfb<\/strong>
\n\u4f8b\uff1a\u65b0\u95fb\u7c7b-\u65b0\u95fb\u7c7b\u578b\u7c7b
\nmodels.ManyToManyField() \u5b9a\u4e49\u5728\u54ea\u4e2a\u7c7b\u4e2d\u90fd\u53ef\u4ee5\u3002
\n3\uff09\u4e00\u5bf9\u4e00\u5173\u7cfb<\/strong>
\n\u4f8b\uff1a\u5458\u5de5\u57fa\u672c\u4fe1\u606f\u7c7b-\u5458\u5de5\u8be6\u7ec6\u4fe1\u606f\u7c7b
\nmodels.OneToOneField() \u5b9a\u4e49\u5728\u54ea\u4e2a\u7c7b\u4e2d\u90fd\u53ef\u4ee5\u3002 <\/p>\n
7. django\u4e2d\u95f4\u4ef6\u7684\u4f7f\u7528\uff1f<\/h5>\n
<\/p>
<\/div>
\u67e5\u770b\u66f4\u591a<\/h2>
\u8054\u7cfb\u7ba1\u7406\u5458\u5fae\u4fe1tutu19192010\uff0c\u6ce8\u518c\u8d26\u53f7<\/p>\n<\/div>
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Register<\/a><\/div>
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