Grails 技巧 - Controller 篇

1.Default Action

Controller 默认Action为 index 可以修改为其它：

static defaultAction = "list"

2.Interceptors

Before Advice

def beforeInterceptor = {
    log.trace("Executing action $actionName with params $params")
}

After Advice

def afterInterceptor = { model ->
    log.trace("Executed $actionName which resulted in model: $model")
}

3.Scoped

Controller 默认scope 为 prototype ，可以修改为session ，singleton

在Controller中

static scope = "singleton"

全局设置 （Config.groovy ）

grails.controllers.defaultScope = "singleton"

4.Data Binding 安全问题解决方案

只绑定指定域

def p = Person.get(1)
p.properties['firstName','lastName'] = params

排除域

def p = new Person()
bindData(p, params, [exclude: 'dateOfBirth'])

Bindable Constraint

class User {
    /* userName and salary would be bindable by default */
    String userName
    BigDecimal salary

    /* group and numberOfActiveGroups would not be bindable by default */
    def group
    transient int numberOfActiveGroups

    static constraints = {
        salary bindable: false
        group bindable: true
    }
}

5.渲染 JSON 数组用 array

def list() {
    def results = Book.list()

    render(contentType: "text/json") {
        books = array {
            for (b in results) {
                book title: b.title
            }
        }
    }
}

输出如下：

[
    {title:"The Stand"},
    {title:"The Shining"}
]

6.Type Conversion Methods （int,boolean, long, char, short,date）

def total = params.int('total')

def total = params.int('total', 42) // total 为空的时候 为42

def date = params.date('date','yyyy-MM-dd')

处理多值情况

for (name in params.list('name')) {
    println name
}

7.Binary Response

def createZip() {
    byte[] zip = ... // create the zip from some source
    render file: zip
}

8.处理重复表单提交

view

<g:form useToken="true" ...>

controller

withForm {
   // good request
}.invalidToken {
   // bad request
}

9.用 forward 避免 HTTP redirect

forward action: "show"

forward controller: "book", action: "list"

forward action: "show", id: 4, params: [author: "Stephen King"]

forward controller: "book", action: "show"

10.获取/WEB-INF下 资源

def doSomething() {
        def input
        try {
            input = servletContext.getResourceAsStream("/WEB-INF/myscript.groovy")
            def result = new GroovyShell().evaluate(input.text)
            render result
        }
        finally {
            input.close()
        }
}