DecimalField类型:固定精度的十进制数,一般用来存金额相关的数据.额外的参数包括DecimalField.max_digits(整个数字的长度)和DecimalField.decimal_places(小数点后面的有效位数) 模型定义时, DecimalField类型字段如下定义: aaf_1kg_all = models.DecimalField(blank=True, null=True) 报错:(fields.E130) DecimalFields must define a '…

第 1 章 课程介绍 1-1 项目演示和课程介绍: 第 2 章 Windows下搭建开发环境 2-1 Pycharm.Navicat和Python解释器的安装: Pycharmhttp://www.jetbrains.com/pycharm/ MacOS 版本的MySQL 8.0.12: Navicat for MySQL 11.1.3: Python 2.7.15: Pycharm Professional 2018.3; http://www.jetbrains.com/pycharm/ 2…

You can use predefined attributes to attach metadata to type members. You can also define a custom attribute by creating a new class inheriting from System.Attribute. The class name must end in "Attribute". You typically define a conostructor th…

Fields Basic fields class openerp.fields.Field(string=None, **kwargs) The field descriptor contains the field definition, and manages accesses and assignments of the corresponding field on records. The following attributes may be provided when instan…

了解attribute Attribute 只是将一些附加信息与某个目标元素关联起来的方式. Attribute 是一个类,这个类可以提供一些字段和属性,不应提供公共方法,事件等.在定义attribute类的构造方法,字段和属性时,对数据类型有严格的要求,一般要求为: Boolean, Char, Byte, Sbyte, Int16, UInt16, Int32, Int64,Single, Double, String, Type, Object, Enum, 可以使用数组,但是并不提倡使用…

cite 表示引用到某一本书籍名称,默认样式为斜体,q 表示直接引用到里面的话,大块的引用使用block默认样式将增加“双引号” ,关键的词用<b>默认为粗体:一些技术术语则用<i>来表示,为斜体 ol标签为有序列表,在出现类似排行榜这样的信息块时,比较适合使用.可以通过<ol type="a">来指定ol列表自增symbol 第一个ol的li元素 第二个ol的li元素 dl为自定义列表,一般用来实现类似术语表这样的功能 <object>…

class property(object): """ Property attribute. fget function to be used for getting an attribute value fset function to be used for setting an attribute value fdel function to be used for del'ing an attribute doc docstring Typical use is t…

===================== Model field reference ===================== .. module:: django.db.models.fields :synopsis: Built-in field types. .. currentmodule:: django.db.models This document contains all the API references of :class:Field including the fie…

Android Lint Checks Here are the current list of checks that lint performs as of Android Studio 2.3 dev:     Correctness ===========   AdapterViewChildren ------------------- Summary: AdapterViews cannot have children in XML   Priority: 10 / 10 Sever…

1 collections系列 方法如下 class Counter(dict): '''Dict subclass for counting hashable items. Sometimes called a bag or multiset. Elements are stored as dictionary keys and their counts are stored as dictionary values. >>> c = Counter('abcdeabcdabcaba'…