postgresql 使用 Ecto 和 Elixir 的默认日期时间
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/28506589/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Default datetime with Ecto & Elixir
提问by MartinElvar
I've just started working Elixir & Phoenix today, i am trying to add Ecto as a mapper, but i'm having some trouble using time.
我今天刚刚开始使用 Elixir & Phoenix，我正在尝试将 Ecto 添加为映射器，但是我在使用时间时遇到了一些麻烦。
This is my model.
这是我的模型。
schema "users" do
field :name, :string
field :email, :string
field :created_at, :datetime, default: Ecto.DateTime.local
field :updated_at, :datetime, default: Ecto.DateTime.local
end
I'm trying to set the created_at and updated_at per default, but when i try to compile this, i get the following error.
我试图默认设置 created_at 和 updated_at，但是当我尝试编译它时，出现以下错误。
== Compilation error on file web/models/user.ex ==
** (ArgumentError) invalid default argument `%Ecto.DateTime{day: 13, hour: 19, min: 47, month: 2, sec: 12, year: 2015}` for `:datetime`
lib/ecto/schema.ex:687: Ecto.Schema.check_default!/2
lib/ecto/schema.ex:522: Ecto.Schema.__field__/4
web/models/board.ex:9: (module)
(stdlib) erl_eval.erl:657: :erl_eval.do_apply/6
There is not much help to get in the documentation, what would be the correct way to do this?
在文档中没有太多帮助，正确的方法是什么？
回答by misaelpc
Defaults fields names are :inserted_atand :updated_atbut you can merge with your own field names, passing a keyword list
默认字段名称是 :inserted_at，:updated_at但您可以与自己的字段名称合并，传递关键字列表
schema "users" do
field :name, :string
field :email, :string
timestamps([{:inserted_at,:created_at}])
end
回答by whatyouhide
:datetimeis the native Postgres data type for, well a datetime; this data type maps to a two-elements Elixir tuple ({{yy, mm, dd}, {hh, mm, ss}}). An %Ecto.DateTime{}struct is not a two-elements tuple, hence the compilation error.
:datetime是用于日期时间的本地 Postgres 数据类型；此数据类型映射到一个包含两个元素的 Elixir 元组 ( {{yy, mm, dd}, {hh, mm, ss}})。的%Ecto.DateTime{}结构不是一个两个元素的元组，因此编译错误。
You may want to set the type of your fields to Ecto.DateTime, it should all work seamlessly.
您可能希望将字段的类型设置为Ecto.DateTime，它应该都能无缝地工作。
Hereis the relevant documentation about primitive types and non-primitive types.
这是关于原始类型和非原始类型的相关文档。
PSyou may also want to have a look at Ecto.Schema.timestamps/1, which is macro that expands to basically what you wrote manually (it adds the created_atand updated_atfields and it let's you choose what type they should be, defaulting to Ecto.DateTime):
PS，您可能还想看看Ecto.Schema.timestamps/1，这是一个宏，基本上可以扩展到您手动编写的内容（它添加created_at和updated_at字段，让您选择它们应该是什么类型，默认为Ecto.DateTime）：
schema "users" do
field :name, :string
field :email, :string
timestamps
end
回答by G Amini
You could also consider having the default not be in the schema, but in the migration: "created_at timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP"
您还可以考虑让默认值不在架构中，而是在迁移中： "created_at timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP"
