Ruby on Rails Study Notes (1)

1	Check whether the entered content is empty.	In Models
	Validates_presence_of: title,: Description,: image_url
2	Verify that the entered content is Numeric
	Validates_numericality_of: Price
3	Verify that the price of the input data is no less than 0.01
	Protected
	Def validate
	Errors. Add (: price, "shocould be at least 0.01") if price. nil? | Price <0.01
	End
4	Verify a field. duplicate fields are not allowed in the database.
	Validates_uniqueness_of: Title
5	Verify image URL Connection
	Validates_format_of: image_url, : With => % R {\. (GIF | JPG | PNG) $} I, : Message => "must be a URL for a GIF, JPG, PNG Image"
6	Adjust a style sheet
	Find the row of the style table in the HTML. ERB file of the APP/views/layouts directory and change it
	<% = Stylesheet_link_tag 'scaffol', 'dest' %>
7	A DataGrid
	<% For product in @ products %>
	<Tr valign = "TOP" class = "<% = Cycle ('LIST-line-odd', 'LIST-line-even') %>">	Line Style Alternation
	<TD>
	</TD>
	& Lt; TD width = "60%" & gt;
	<SPAN class = "list-title"> <% = H (product. Title) %> </span> <br/>	H () converts HTML, 2.0 seems to be useless
	<% = H (truncate (product. Description, 80) %>	Truncate () truncate the string. 2.0 does not seem to be 80.
	</TD>
	<TD class = "list-Actions">
	<% = Link_to 'show ',: Action => 'show',: Id => product %> <br/>
	<% = Link_to 'edit',: Action => 'edit',: Id => product %> <br/>
	<% = Link_to 'deststroy', {: Action => 'deststroy',: Id => product },
	: Confirm => "Are you sure? ",	Added. Confirm deletion dialog box
	: Method =>: Post %>	After deletion, You need to refresh the page
	</TD>
	</Tr>
	<% End %>
8	Add a parameter to the Controller.
	Def Index	When a controller is called, if no specific action is specified, index is used by default.
	@ Products = product. find_products_find_for_sale	This parameter automatically finds the find_products_find_for_sale method of models and obtains the value.
	End
9	Declare a class method in Models
	Def self. find_product_for_sale	Self. Declares class methods, which can be called by using product., without limiting the Controller
	Find (: All,: Order => "title ")
	End
10	The HTML. ERB file in the app/views/layouts directory is the CSS file used to change the page.
	The. rhtml in the app/views/layouts directory is a template file and provides a layout template.
11	Add a template file rhtml
	<Div id = "banner">
	<% = Image_tag ("logo.png") %>
	<% = @ Page_title | "pragmatic bookshelf" %>	Specify the content to be displayed in the header
	</Div>
	<Div id = "columns">
	<Div id = "side">
	<A href = "http: // www..."> Home </a> <br/>
	<A href = "http: // www.../faq"> Questions </a> <br/>
	<A href = "http: // www.../News"> News </a> <br/>
	<A href = "http: // www.../contact"> contact </a> <br/>
	</Div>
	<Div id = "Main">
	<% = Yield: Layout %>	The actual content of the page is displayed at this location
	</Div>
	</Div>
12	International Currency output
	<SPAN class = "price"> <% = number_to_currency (product. Price) %> </span>	Number_to_currency ()