{"id":6185,"date":"2022-04-06T13:12:27","date_gmt":"2022-04-06T05:12:27","guid":{"rendered":"https:\/\/egonlin.com\/?p=6185"},"modified":"2022-04-16T19:47:08","modified_gmt":"2022-04-16T11:47:08","slug":"%e7%ac%ac%e5%85%ad%e8%8a%82%ef%bc%9a%e6%a8%a1%e5%9e%8b%e5%b1%82%e8%a1%a8%e6%93%8d%e4%bd%9c%e4%b9%8bfields%e5%ad%97","status":"publish","type":"post","link":"https:\/\/egonlin.com\/?p=6185","title":{"rendered":"\u7b2c\u516d\u8282\uff1a\u6a21\u578b\u5c42\u8868\u64cd\u4f5c\u4e4bFields\u5b57\u6bb5"},"content":{"rendered":"<h1>\u6a21\u578b\u5c42\u8868\u64cd\u4f5c\u4e4bFields\u5b57\u6bb5<\/h1>\n<p><div class='fancybox-wrapper lazyload-container-unload' data-fancybox='post-images' href='https:\/\/egonlin.com\/wp-content\/uploads\/2022\/04\/\u8868\u64cd\u4f5c\u4e4bFields\u5b57\u6bb51.jpg'><img class=\"lazyload lazyload-style-2\" src=\"data:image\/svg+xml;base64,PCEtLUFyZ29uTG9hZGluZy0tPgo8c3ZnIHdpZHRoPSIxIiBoZWlnaHQ9IjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyIgc3Ryb2tlPSIjZmZmZmZmMDAiPjxnPjwvZz4KPC9zdmc+\"  data-original=\"https:\/\/egonlin.com\/wp-content\/uploads\/2022\/04\/\u8868\u64cd\u4f5c\u4e4bFields\u5b57\u6bb51.jpg\" src=\"data:image\/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB\/AAffA0nNPuCLAAAAAElFTkSuQmCC\" alt=\"\" \/><\/div><\/p>\n<h2>\u4e00\u3001\u5b57\u6bb5\u540d\u547d\u540d\u9650\u5236<\/h2>\n<p>Fields\u5b57\u6bb5\u88ab\u6307\u5b9a\u4e3a\u6a21\u578b\u7c7b\u7684\u7c7b\u5c5e\u6027\uff0c\u662f\u6a21\u578b\u6700\u91cd\u8981\u7684\u90e8\u5206\uff0c\u4e5f\u662f\u6a21\u578b\u552f\u4e00\u5fc5\u987b\u8981\u6709\u7684\u90e8\u5206\uff0c\u662f\u7528\u6765\u5b9a\u4e49\u6570\u636e\u5e93\u5b57\u6bb5\u7684\u3002<\/p>\n<p>Django \u5bf9\u5b57\u6bb5\u7684\u547d\u540d\u8bbe\u7f6e\u4e86\u4e00\u4e9b\u9650\u5236\uff1a<\/p>\n<p>1\u3001\u6ce8\u610f\u5b57\u6bb5\u540d\u4e0d\u8981\u9009\u62e9\u4e0e\u6a21\u578bAPI\u51b2\u7a81\u7684\u540d\u5b57\uff0c\u5982clean\u3001save\u6216delete\u7b49<\/p>\n<p>2\u3001\u5b57\u6bb5\u540d\u4e0d\u80fd\u662fPython\u4fdd\u7559\u5b57\uff0c\u56e0\u4e3a\u8fd9\u5c06\u5bfc\u81f4Python\u8bed\u6cd5\u9519\u8bef\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code class=\"language-python\">class Example(models.Model):\n    pass = models.IntegerField() # &#039;pass&#039;\u662f\u4fdd\u7559\u5b57 <\/code><\/pre>\n<p>3\u3001\u7531\u4e8eDjango \u67e5\u8be2\u8bed\u6cd5\u7684\u5de5\u4f5c\u65b9\u5f0f\uff0c\u6240\u4ee5\u5b57\u6bb5\u540d\u79f0\u4e2d\u8fde\u7eed\u7684\u4e0b\u5212\u7ebf\u4e0d\u80fd\u8d85\u8fc7\u4e24\u4e2a\u3002 \u4f8b\u5982\uff1a<\/p>\n<pre><code class=\"language-python\">class Example(models.Model):\n    foo__bar = models.IntegerField() # \u9519\u8bef\uff0c\u56e0\u5b57\u6bb5&#039;foo__bar&#039;\u5e26\u6709\u4e24\u4e2a\u4e0b\u5212\u7ebf<\/code><\/pre>\n<p>4\u3001\u51fa\u4e8e\u7c7b\u4f3c\u7684\u539f\u56e0\uff0c\u5b57\u6bb5\u540d\u4e0d\u80fd\u4ee5\u4e0b\u5212\u7ebf\u7ed3\u5c3e\u3002<\/p>\n<p>\u4e0a\u8ff0\u53ea\u662f\u9488\u5bf9\u6a21\u578b\u5b57\u6bb5\u7684\u9650\u5236\uff0c\u5e76\u4e0d\u662f\u9488\u5bf9\u6570\u636e\u5e93\u5217\u7684\u9650\u5236\uff0c\u6211\u4eec\u7684\u6a21\u578b\u5b57\u6bb5\u540d\u4e0e\u6570\u636e\u5e93\u5217\u540d\u5e76\u4e0d\u662f\u5339\u914d\u7684\uff0c\u53ef\u4ee5\u7528db_column\u5b57\u6bb5\u6307\u5b9a\u6570\u636e\u5e93\u540d<\/p>\n<pre><code class=\"language-python\">class Example(models.Model):\n    # \u6570\u636e\u5e93\u4e2d\u5b57\u6bb5\u540d\u6539\u4e3aaaa__aaa\uff0c\u4f46\u67e5\u8be2\u65f6\u4ecd\u7528aaa\n    aaa=models.CharField(max_length=10,db_column=&#039;aaa__aaa&#039;)  \n    bbb=models.CharField(max_length=10,db_column=&#039;bbb_&#039;)<\/code><\/pre>\n<p>5\u3001SQL \u7684\u4fdd\u7559\u5b57\u4f8b\u5982select\u3001where \u548cjoin\uff0c\u53ef\u4ee5\u7528\u4f5c\u6a21\u578b\u7684\u5b57\u6bb5\u540d\uff0c\u56e0\u4e3aDjango \u4f1a\u5bf9\u5e95\u5c42\u7684SQL \u67e5\u8be2\u8bed\u53e5\u4e2d\u7684\u6570\u636e\u5e93\u8868\u540d\u548c\u5217\u540d\u8fdb\u884c\u8f6c\u4e49\u3002 \u5b83\u6839\u636e\u4f60\u7684\u6570\u636e\u5e93\u5f15\u64ce\u4f7f\u7528\u4e0d\u540c\u7684\u5f15\u7528\u8bed\u6cd5\u3002\u5373\u4f7f\u53ef\u4ee5\uff0c\u5f53\u6211\u4eec\u8fd8\u662f\u4e0d\u63a8\u8350\u5e94\u7528\u4fdd\u7559\u5b57\u3002<\/p>\n<h2>\u4e8c\u3001\u5b57\u6bb5\u7c7b\u578b<\/h2>\n<p>\u5b57\u6bb5\u7c7b\u578b\uff1a<\/p>\n<pre><code class=\"language-python\">#1\u3001AutoField\nint\u81ea\u589e\u5217\uff0c\u5fc5\u987b\u586b\u5165\u53c2\u6570 primary_key=True\u3002\u5f53model\u4e2d\u5982\u679c\u6ca1\u6709\u81ea\u589e\u5217\uff0c\u5219\u81ea\u52a8\u4f1a\u521b\u5efa\u4e00\u4e2a\u5217\u540d\u4e3aid\u7684\u5217\u3002\n\n#2\u3001IntegerField\n\u4e00\u4e2a\u6574\u6570\u7c7b\u578b,\u8303\u56f4\u5728 -2147483648 to 2147483647\u3002\n\n#3\u3001CharField\n\u5b57\u7b26\u7c7b\u578b\uff0c\u5fc5\u987b\u63d0\u4f9bmax_length\u53c2\u6570\uff0c max_length\u8868\u793a\u5b57\u7b26\u957f\u5ea6\u3002\n\n#4\u3001DateField\n\u65e5\u671f\u5b57\u6bb5\uff0c\u65e5\u671f\u683c\u5f0f  YYYY-MM-DD\uff0c\u76f8\u5f53\u4e8ePython\u4e2d\u7684datetime.date()\u5b9e\u4f8b\u3002\n\n#5\u3001DateTimeField\n\u65e5\u671f\u65f6\u95f4\u5b57\u6bb5\uff0c\u683c\u5f0f YYYY-MM-DD HH:MM[:ss[.uuuuuu]][TZ]\uff0c\u76f8\u5f53\u4e8ePython\u4e2d\u7684datetime.datetime()\u5b9e\u4f8b<\/code><\/pre>\n<p>\u793a\u4f8b<\/p>\n<pre><code class=\"language-python\">from django.db import models\n\nclass Musician(models.Model):\n    first_name = models.CharField(max_length=50)\n    last_name = models.CharField(max_length=50)\n    instrument = models.CharField(max_length=100)\n\nclass Album(models.Model):\n    artist = models.ForeignKey(Musician, on_delete=models.CASCADE)\n    name = models.CharField(max_length=100)\n    release_date = models.DateField()\n    num_stars = models.IntegerField()<\/code><\/pre>\n<p>\u2022 \u66f4\u591a\u8be6\u89c1\uff1a<\/p>\n<p>\u9644\u5f551\uff1a\u5e38\u7528\u5b57\u6bb5\u548c\u975e\u5e38\u7528\u5b57\u6bb5\u5408\u96c6<\/p>\n<p>\u2022 django\u63d0\u4f9b\u4e86\u51e0\u5341\u4e2a\u5185\u7f6e\u7684\u5b57\u6bb5\u7c7b\u578b\uff0c\u8be6\u89c1<br \/>\n<a href=\"#model-field-types\"><em>https:\/\/docs.djangoproject.com\/en\/3.0\/ref\/models\/fields\/#model-field-types<\/em><\/a><\/p>\n<p>\u2022 \u5982\u679cdjango\u7684\u5185\u7f6e\u7c7b\u578b\u65e0\u6cd5\u6ee1\u8db3\u9700\u6c42\uff0c\u4e5f\u53ef\u4ee5\u81ea\u5b9a\u4e49<br \/>\n<a href=\"https:\/\/docs.djangoproject.com\/en\/3.0\/howto\/custom-model-fields\/\"><em>https:\/\/docs.djangoproject.com\/en\/3.0\/howto\/custom-model-fields\/<\/em><\/a><\/p>\n<h2>\u4e09\u3001\u5b57\u6bb5\u9009\u9879\/\u53c2\u6570<\/h2>\n<p>\u6bcf\u4e2a\u5b57\u6bb5\u90fd\u6709\u4e00\u7ec4\u7279\u5b9a\u4e8e\u8be5\u5b57\u6bb5\u7684\u53c2\u6570\u3002\u4f8b\u5982\u5b57\u6bb5CharField\uff08\u53ca\u5176\u5b50\u7c7b\uff09\u5fc5\u987b\u5b9a\u4e49\u4e00\u4e2amax_length\u53c2\u6570\uff0c\u8be5\u53c2\u6570\u6307\u5b9a\u7528\u4e8e\u5b58\u50a8\u6570\u636e\u7684VARCHAR\u6570\u636e\u5e93\u5b57\u6bb5\u7684\u5927\u5c0f\uff0c\u8fd9\u90e8\u5206\u53c2\u6570\u53c2\u8003\u5b98\u7f51\u6216\u63d0\u793a\u6307\u5b9a\u5373\u53ef\u3002<\/p>\n<p>\u6211\u4eec\u4e3b\u8981\u8ba8\u8bba\u4e00\u4e0b\u53ef\u7528\u4e8e\u6240\u6709\u5b57\u6bb5\u7c7b\u578b\u7684\u516c\u5171\u53c2\u6570\uff0c\u5f53\u7136\uff0c\u6240\u6709\u7684\u90fd\u662f\u53ef\u9009\u7684<\/p>\n<p>1\u3001null\uff1a<br \/>\n\u5982\u679c\u4e3aTrue\uff0cDjango\u5c06\u5728\u6570\u636e\u5e93\u4e2d\u5c06\u7a7a\u503c\u5b58\u50a8\u4e3aNULL\u3002\u9ed8\u8ba4\u503c\u4e3aFalse\u3002<\/p>\n<p>2\u3001blank\uff1a<br \/>\n\u5982\u679c\u4e3aTrue\uff0c\u5219\u8be5\u5b57\u6bb5\u5141\u8bb8\u4e3a\u7a7a\u3002\u9ed8\u8ba4\u503c\u4e3aFalse\u3002<\/p>\n<p>\u6ce8\u610f\uff0c\u8fd9\u4e0enull\u4e0d\u540c\u3002null\u7eaf\u7cb9\u4e0e\u6570\u636e\u5e93\u76f8\u5173\uff0c\u800cblank\u5219\u4e0e\u9a8c\u8bc1\u76f8\u5173\u3002\u5982\u679c\u5b57\u6bb5\u7684blank=True\uff0c\u5219\u8868\u5355\u9a8c\u8bc1\u5c06\u5141\u8bb8\u8f93\u5165\u7a7a\u503c\u3002\u5982\u679c\u5b57\u6bb5\u4e3a\u7a7a=\u5047\uff0c\u5219\u8be5\u5b57\u6bb5\u662f\u5fc5\u9700\u7684\u3002<\/p>\n<p>3\u3001unique:<\/p>\n<p>\u5982\u679c\u4e3aTrue\uff0c\u8be5\u5b57\u6bb5\u5fc5\u987b\u662f\u552f\u4e00\u7684<\/p>\n<p>4\u3001db_index<\/p>\n<p>\u5982\u679cdb_index=True \u5219\u4ee3\u8868\u7740\u4e3a\u6b64\u5b57\u6bb5\u8bbe\u7f6e\u7d22\u5f15\u3002<\/p>\n<p>5\u3001db_column<\/p>\n<p>\u6307\u5b9a\u6570\u636e\u5bf9\u5e94\u7684\u5b57\u6bb5\u540d<br \/>\nname = models.CharField(max_length=64, db_column=&#8217;book_name&#8217;)<\/p>\n<p>\u9ed8\u8ba4\u5b57\u6bb5\u540d\u4e3aname\uff0c\u6307\u5b9adb_column\u540e\uff0c\u6570\u636e\u5e93\u8868\u5b57\u6bb5\u540d\u4e3abook_name<\/p>\n<p>6\u3001choices<\/p>\n<p>\u7528\u4e8e\u6307\u5b9a\u4e00\u4e2a\u4e8c\u5143\u7ec4\uff0c\u5982\u679c\u7ed9\u5b9a\u4e86\u6b64\u9009\u9879\uff0c\u5219admin\u754c\u9762\u9ed8\u8ba4\u8868\u5355\u5c0f\u90e8\u4ef6\u5c06\u662f\u4e00\u4e2a\u9009\u62e9\u6846\uff0c\u800c\u4e0d\u662f\u6807\u51c6\u6587\u672c\u5b57\u6bb5\uff0c\u5e76\u4e14\u5c06\u9009\u62e9\u9650\u5236\u4e3a\u7ed9\u5b9a\u7684\u9009\u9879\uff0c\u5982\u4e0b<\/p>\n<pre><code class=\"language-python\">from django.db import models\n\nclass Person(models.Model):\n    # \u6bcf\u4e2a\u5143\u7ec4\u7684\u7b2c\u4e8c\u4e2a\u5143\u7d20\u7528\u6765\u5728amdin\u7ba1\u7406\u754c\u9762\u663e\u793a\uff0c\u800c\u7b2c\u4e00\u4e2a\u5143\u7d20\u624d\u662f\u88ab\u5b58\u5165\u6570\u636e\u5e93\u4e2d\u7684\u503c\n    SHIRT_SIZES = (\n        (&#039;S&#039;, &#039;Small&#039;),\n        (&#039;M&#039;, &#039;Medium&#039;),\n        (&#039;L&#039;, &#039;Large&#039;),\n    )\n    name = models.CharField(max_length=60)\n    shirt_size = models.CharField(max_length=1, choices=SHIRT_SIZES)\n\n>&gt;&gt; p = Person(name=&quot;Fred Flintstone&quot;, shirt_size=&quot;L&quot;)\n>&gt;&gt; p.save()\n>&gt;&gt; p.shirt_size\n&#039;L&#039;\n>&gt;&gt; p.get_shirt_size_display() # \u53ef\u4ee5\u4f7f\u7528get_FOO_display()\u65b9\u6cd5\u8bbf\u95ee\u5177\u6709\u9009\u9879\u7684\u5b57\u6bb5\u7684\u663e\u793a\u503c\n&#039;Large&#039;<\/code><\/pre>\n<p>7\u3001default<br \/>\n\u5b57\u6bb5\u7684\u9ed8\u8ba4\u503c\u3002\u8fd9\u53ef\u4ee5\u662f\u503c\u6216\u53ef\u8c03\u7528\u5bf9\u8c61\u3002\u5982\u679c\u53ef\u8c03\u7528\uff0c\u5219\u6bcf\u6b21\u521b\u5efa\u65b0\u5bf9\u8c61\u65f6\u90fd\u5c06\u8c03\u7528\u5b83\u3002<\/p>\n<pre><code class=\"language-python\">from django.db import models\n\ndef func():\n    print(&#039;from func&#039;)\n\nclass Person(models.Model):\n    SHIRT_SIZES = (\n        (&#039;S&#039;, &#039;Small&#039;),\n        (&#039;M&#039;, &#039;Medium&#039;),\n        (&#039;L&#039;, &#039;Large&#039;),\n    )\n    name = models.CharField(max_length=60,null=True,default=func)\n    shirt_size = models.CharField(max_length=1, choices=SHIRT_SIZES)\n\n# \u9996\u5148\u6211\u4eec\u8bbe\u7f6enull=True\uff0cdefault=\u51fd\u6570\n# \u7136\u540e\u6267\u884c\uff0c\u5f53\u63d2\u5165\u503c\u4e3a\u7a7a\u65f6\uff0c\u4f1a\u4f7f\u7528\u9ed8\u8ba4\u503c\uff0c\u5982\u679c\u6b64\u65f6\u9ed8\u8ba4\u503c\u4e3a\u51fd\u6570\uff0c\u5219\u4f1a\u89e6\u53d1\u51fd\u6570\u7684\u6267\u884c\n>&gt;&gt; p = Person()\nfrom func\n>&gt;&gt; p.save()<\/code><\/pre>\n<p>8\u3001auto_now_add<\/p>\n<p>\u9488\u5bf9 DateField\u548cDateTimeField\u53ef\u4ee5\u8bbe\u7f6eauto_now_add=True\uff0c\u65b0\u589e\u5bf9\u8c61\u65f6\u4f1a\u81ea\u52a8\u6dfb\u52a0\u5f53\u524d\u65f6\u95f4<\/p>\n<pre><code class=\"language-python\">create_time=models.DateTimeField(auto_now_add=True) # \u53ea\u9488\u5bf9\u521b\u5efa\uff0c\u4e0d\u9488\u5bf9\u4fee\u6539<\/code><\/pre>\n<p>9\u3001auto_now<\/p>\n<p>\u9488\u5bf9 DateField\u548cDateTimeField\u53ef\u4ee5\u8bbe\u7f6eauto_now=True\uff0c\u65b0\u589e\u6216\u4fee\u6539\u5bf9\u8c61\u90fd\u4f1a\u81ea\u52a8\u586b\u5145\u5f53\u524d\u65f6\u95f4<\/p>\n<pre><code class=\"language-python\">modify_time=models.DateTimeField(auto_now=True) # \u9488\u5bf9\u521b\u5efa\u4ee5\u53ca\u4fee\u6539\u90fd\u6709\u6548<\/code><\/pre>\n<p><strong><em>*\u5f3a\u8c03\uff1a*<\/em><\/strong><\/p>\n<p><strong><em>\\<\/em>1*****<\/strong>*)*<strong>**<\/strong>*\u3001\u9009\u9879auto_now\u3001auto_now_add\u548cdefault\u662f\u4e92\u65a5\u7684\u3002\u53ea\u80fd\u6709\u4e00\u4e2a\u3002****<\/p>\n<p><strong><em>\\<\/em>2*****<\/strong>*)*<strong>**<\/strong>*\u3001auto_now=True\u7684\u81ea\u52a8\u66f4\u65b0\u6709\u4e00\u4e2a\u6761\u4ef6\uff0c\u5c31\u662f\u8981\u901a\u8fc7django\u7684model\u5c42\uff0c\u90a3\u6709\u54ea\u4e9b\u64cd\u4f5c\u662f\u901a\u8fc7model\u5c42\u5462\uff1f\uff1f\uff1f****<\/p>\n<p>\u5982create\u6216\u662fsave\u65b9\u6cd5\uff0c\u5219\u662f\u901a\u8fc7model\u5c42<\/p>\n<p>\u5982\u679c\u662ffilter\u4e4b\u540eupdate\u65b9\u6cd5\uff0c\u5219\u76f4\u63a5\u8c03\u7528\u7684\u662fsql\uff0c\u4e0d\u4f1a\u901a\u8fc7model\u5c42\uff0c\u6240\u4ee5\u4e0d\u4f1a\u81ea\u52a8\u66f4\u65b0\u6b64\u65f6\u95f4\u3002\u5b98\u65b9\u89e3\u91ca\u5982\u4e0b<\/p>\n<pre><code class=\"language-python\">What you consider a bug, others may consider a feature, e.g. usingupdate_fieldsto bypass updating fields withauto_now. In fact, I wouldn&#039;t expectauto_nowfields to be updated if not present inupdate_fields.<\/code><\/pre>\n<p><strong><em>*\u6240\u4ee5\uff0c\u60f3\u8ba9auto_now=True\u751f\u6548\u7684\u529e\u6cd5\u662f\uff1a*<\/em><\/strong>\u5f3a\u5236\u6539\u6210save()\u6216\u8005\u662fupdate\u65f6\u624b\u52a8\u4f20\u5165\u65f6\u95f4\u3002<\/p>\n<p>\u603b\u7ed3<\/p>\n<pre><code class=\"language-python\">auto_now_add=True\nauto_now=True\n\u4e8c\u8005\u7684\u76f8\u540c\u4e4b\u5904\uff0c\u5728\u9996\u6b21\u63d2\u5165\u8bb0\u5f55\u65f6\uff0c\u65e0\u8bba\u662f\u4f7f\u7528create\u8fd8save\uff0c\u90fd\u4f1a\u81ea\u52a8\u586b\u5145\u65f6\u95f4\n\u4e8c\u8005\u7684\u4e0d\u540c\u4e4b\u5904\u5728\u4e8e\uff0c\u5bf9\u4e8e\u5df2\u7ecf\u5b58\u5728\u7684\u8bb0\u5f55\uff0c\u518d\u8fdb\u884cupdate\u6216\u8005save\u64cd\u4f5c\u65f6\n\nauto_now_add=True(\u591a\u7528\u4e8e\u8bb0\u5f55\u6570\u636e\u7684\u521b\u5efa\u65f6\u95f4)\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u65e0\u8bba\u662fupdate\u8fd8\u662f.save()\u90fd\u4e0d\u80fd\u66f4\u6539\u4ed6\u7684\u503c\uff0c\u6240\u4ee5\u5176\u4e00\u822c\u7528\u4e8e\u8bb0\u5f55\u6570\u636e\u7684\u521b\u5efa\u65f6\u95f4\n\nauto_now=True(\u591a\u7528\u4e8e\u8bb0\u5f55\u6570\u636e\u7684\u66f4\u65b0\u65f6\u95f4)\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 update\u65b9\u6cd5\u4e0d\u80fd\u6539\u53d8\u5176\u65f6\u95f4\uff0c\u9664\u975eupdatet\u65f6\u81ea\u5df1\u624b\u52a8\u4f20\u5165\u65f6\u95f4\u624d\u53ef\u4ee5\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 .save() \u65f6auto_now\u80fd\u591f\u81ea\u52a8\u586b\u5145\u65f6\u95f4\n          \u4f8b\u5982\uff1a\n          obj=Book.objects.filter(id=8).first()\n          obj.title = &quot;xxx&quot;\n          obj.save()  # auto_now\u7684\u5b57\u6bb5\u4f1a\u81ea\u52a8\u66f4\u65b0\u65f6\u95f4<\/code><\/pre>\n<p>3\u6ce8\u610f\u65f6\u533a\u8bbe\u7f6e\uff0c\u4fee\u6539\u914d\u7f6e\u6587\u4ef6<\/p>\n<pre><code class=\"language-python\">TIME_ZONE = &#039;Asia\/Shanghai&#039;\nUSE_TZ = False  # \u5fc5\u987b\u6539\u4e3aFalse<\/code><\/pre>\n<p>help_text,<br \/>\n\u7528\u4e8e\u5728admin\u7ba1\u7406\u754c\u9762\u663e\u793a\u7684\u989d\u5916\u201c\u5e2e\u52a9\u201d\u6587\u672c\u3002\u5b83\u5bf9\u4e8e\u6587\u6863\u5f88\u6709\u7528<br \/>\nname = models.CharField(max_length=60,null=True,default=func,help_text=&#8217;\u54c8\u54c8\u54c8\u54c8\u54c8&#8217;)<\/p>\n<p>primary_key<\/p>\n<p>\u5982\u679c\u4e3aTrue\uff0c\u90a3\u4e48\u8fd9\u4e2a\u5b57\u6bb5\u5c31\u662f\u6a21\u578b\u7684\u4e3b\u952e\u3002<\/p>\n<p>\u4e3b\u952e\u5b57\u6bb5\u662f\u53ea\u8bfb\u7684\u3002 \u5982\u679c\u4f60\u5728\u4e00\u4e2a\u5df2\u5b58\u5728\u7684\u5bf9\u8c61\u4e0a\u9762\u66f4\u6539\u4e3b\u952e\u7684\u503c\u5e76\u4e14\u4fdd\u5b58\uff0c\u5e76\u4e0d\u4f1a\u4fee\u6539\uff0c\u800c\u662f\u4f1a\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u5bf9\u8c61\u3002 \u4f8b\u5982\uff1a<\/p>\n<pre><code class=\"language-python\">from django.db import models\n\nclass Fruit(models.Model):\n    name = models.CharField(max_length=100, primary_key=True)\n>&gt;&gt; fruit = Fruit.objects.create(name=&#039;Apple&#039;)\n>&gt;&gt; fruit.name = &#039;Pear&#039;\n>&gt;&gt; fruit.save()\n>&gt;&gt; Fruit.objects.values_list(&#039;name&#039;, flat=True)\n&lt;QuerySet [&#039;Apple&#039;, &#039;Pear&#039;]&gt;\n\u5982\u679c\u4f60\u6ca1\u6709\u6307\u5b9a\u4efb\u4f55\u4e00\u4e2a\u5b57\u6bb5\u7684primary_key=True\uff0cDjango \u5c31\u4f1a\u81ea\u52a8\u6dfb\u52a0\u4e00\u4e2aIntegerField \u5b57\u6bb5\u505a\u4e3a\u4e3b\u952e\uff0c\u6240\u4ee5\u9664\u975e\u4f60\u60f3\u8986\u76d6\u9ed8\u8ba4\u7684\u4e3b\u952e\u884c\u4e3a\uff0c\u5426\u5219\u6ca1\u5fc5\u8981\u8bbe\u7f6e\u4efb\u4f55\u4e00\u4e2a\u5b57\u6bb5\u7684primary_key=True\u3002 \u8be6\u89c1\u4e0b\u4e00\u5c0f\u8282 \u56db \u81ea\u52a8\u4e3b\u952e\u5b57\u6bb5\n \u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0cdjango\u81ea\u52a8\u4f1a\u4e3a\u6bcf\u4e2a\u6a21\u578b\u521b\u5efa\u4e00\u4e2a\u4e3b\u952e\u5b57\u6bb5\uff0c\u8fd9\u79cd\u81ea\u52a8\u7684\u884c\u4e3a\u79f0\u4e4b\u4e3a\u9690\u5f0f\u521b\u5efa\nid = models.AutoField(primary_key=True)<\/code><\/pre>\n<p>\u5982\u679c\u6211\u4eec\u60f3\u81ea\u5b9a\u4e49\u4e3b\u952e\uff0c\u9700\u8981\u4e3a\u4f60\u7684\u67d0\u4e00\u4e2a\u5b57\u6bb5\u6307\u5b9a\u53c2\u6570primary_key=True\uff0c\u8fd9\u79cd\u81ea\u5b9a\u4e49\u884c\u4e3a\u79f0\u4e4b\u4e3a\u663e\u5f0f\u521b\u5efa<br \/>\n\u5982\u679cdjango\u770b\u5230\u4f60\u5df2\u7ecf\u81ea\u5b9a\u4e49\u4e86\u4e3b\u952e\uff0c\u5b83\u5c06\u4e0d\u4f1a\u81ea\u52a8\u521b\u5efaid\u5b57\u6bb5\u5566\uff01<\/p>\n<h2>\u56db\u3001\u8bbe\u7f6e\u5b57\u6bb5\u7684\u81ea\u8ff0\u540d\u5b57<\/h2>\n<p>\u9664ForeignKey\u3001ManyToManyField\u548cOneToOneField\u5916\uff0c\u6bcf\u79cd\u5b57\u6bb5\u7c7b\u578b\u90fd\u91c7\u7528\u53ef\u9009\u7684\u7b2c\u4e00\u4e2a\u4f4d\u7f6e\u53c2\u6570\u4f5c\u4e3a\u8be6\u7ec6\u540d\u79f0\u3002\u5982\u679c\u6ca1\u6709\u6307\u5b9a\u8981\u663e\u793a\u7684\u8be6\u7ec6\u540d\u79f0\uff0cDjango\u5c06\u4f7f\u7528\u5b57\u6bb5\u7684\u5c5e\u6027\u540d\u79f0\u81ea\u52a8\u521b\u5efa\u5b83\uff0c\u5e76\u5c06\u4e0b\u5212\u7ebf\u8f6c\u6362\u4e3a\u7a7a\u683c\u3002<\/p>\n<p>\u5982\u4e0b admin\u7ba1\u7406\u754c\u9762\u5b57\u6bb5\u663e\u793a\u7684\u8be6\u7ec6\u540d\u79f0\u4e3a\uff1a&quot;person&#8217;s first name&quot;<\/p>\n<pre><code class=\"language-python\">first_name = models.CharField(&quot;person&#039;s first name&quot;, max_length=30)\n# first_name = models.CharField(name=&quot;person&#039;s first name&quot;, max_length=30)<\/code><\/pre>\n<p>\u5982\u4e0b\uff0c\u5b57\u6bb5\u663e\u793a\u7684\u8be6\u7ec6\u540d\u5b57\u4e3a\uff1a &quot;first name&quot;:<\/p>\n<pre><code class=\"language-python\">first_name = models.CharField(max_length=30)<\/code><\/pre>\n<p>\u9488\u5bf9ForeignKey\u3001ManyToManyField\u548cOneToOneField\u5b57\u6bb5\uff0c\u7b2c\u4e00\u4e2a\u53c2\u6570\u5fc5\u987b\u4e3a\u6a21\u578b\u7c7b\uff0c\u5982\u679c\u8981\u8bbe\u7f6e\u5b57\u6bb5\u663e\u793a\u7684\u8be6\u7ec6\u540d\u5b57\uff0c\u9700\u8981\u6307\u5b9a\u53c2\u6570verbose_name\uff0c\u5982\u4e0b<\/p>\n<pre><code class=\"language-python\">from django.db import models\n\nclass Person(models.Model):\n    SHIRT_SIZES = (\n        (&#039;S&#039;, &#039;Small&#039;),\n        (&#039;M&#039;, &#039;Medium&#039;),\n        (&#039;L&#039;, &#039;Large&#039;),\n    )\n    name = models.CharField(&#039;\u7528\u6237\u540d&#039;,max_length=60,null=True,help_text=&#039;\u54c8\u54c8\u54c8&#039;)\n    role=models.ForeignKey(to=&#039;Role&#039;,verbose_name=&#039;\u6743\u9650\u9009\u62e9&#039;,on_delete=models.CASCADE,null=True)\n\nclass Role(models.Model):\n    PRIVS = (\n        (0, &#039;superuser&#039;),\n        (1, &#039;user&#039;),\n        (2, &#039;visitor&#039;),\n    )\n\n    role=models.CharField(&#039;\u89d2\u8272&#039;,max_length=20)\n    priv=models.IntegerField(&#039;\u6743\u9650&#039;,choices=PRIVS)<\/code><\/pre>\n<p>\u7ea6\u5b9a\u4fd7\u79f0\u4e0d\u4f1a\u5c06\u8be6\u7ec6\u540d\u79f0\u7684\u7b2c\u4e00\u4e2a\u5b57\u6bcd\u5927\u5199\uff0cdjango\u4f1a\u5728\u9700\u8981\u7684\u5730\u65b9\u81ea\u52a8\u5c06\u7b2c\u4e00\u4e2a\u5b57\u6bcd\u5927\u5199<\/p>\n<h2>\u4e94\u3001\u5efa\u7acb\u8868\u5173\u7cfb<\/h2>\n<p>\u6d89\u53ca\u5230\u5b57\u6bb5ForeignKey\u3001ManyToManyField\u3001OneToOneField\u7684\u4f7f\u7528\uff0c\u8be6\u89c1\u4e0b\u4e00\u5c0f\u8282<\/p>\n<h2>\u516d\u3001\u81ea\u5b9a\u4e49\u5b57\u6bb5\uff08\u4e86\u89e3\uff09<\/h2>\n<p>\u81ea\u5b9a\u4e49char\u7c7b\u578b\u5b57\u6bb5\uff1a<\/p>\n<pre><code class=\"language-python\">class FixedCharField(models.Field):\n    &quot;&quot;&quot;\n    \u81ea\u5b9a\u4e49\u7684char\u7c7b\u578b\u7684\u5b57\u6bb5\u7c7b\n    &quot;&quot;&quot;\n    def __init__(self, max_length, *args, **kwargs):\n        self.max_length = max_length\n        super(FixedCharField, self).__init__(max_length=max_length, *args, **kwargs)\n\n    def db_type(self, connection):\n        &quot;&quot;&quot;\n        \u9650\u5b9a\u751f\u6210\u6570\u636e\u5e93\u8868\u7684\u5b57\u6bb5\u7c7b\u578b\u4e3achar\uff0c\u957f\u5ea6\u4e3amax_length\u6307\u5b9a\u7684\u503c\n        &quot;&quot;&quot;\n        return &#039;char(%s)&#039; % self.max_length\n\nclass Class(models.Model):\n    id = models.AutoField(primary_key=True)\n    title = models.CharField(max_length=25)\n    # \u4f7f\u7528\u81ea\u5b9a\u4e49\u7684char\u7c7b\u578b\u7684\u5b57\u6bb5\n    cname = FixedCharField(max_length=25)<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>\u6a21\u578b\u5c42\u8868\u64cd\u4f5c\u4e4bFields\u5b57\u6bb5 \u4e00\u3001\u5b57\u6bb5\u540d\u547d\u540d\u9650\u5236 Fields\u5b57\u6bb5\u88ab\u6307\u5b9a\u4e3a\u6a21\u578b\u7c7b\u7684\u7c7b\u5c5e\u6027\uff0c\u662f\u6a21\u578b\u6700\u91cd\u8981\u7684\u90e8\u5206 [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":6796,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[3,405],"tags":[],"_links":{"self":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/6185"}],"collection":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6185"}],"version-history":[{"count":0,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/6185\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/media\/6796"}],"wp:attachment":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6185"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6185"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6185"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}