使用条件运算符在 Grails 中呈现“作为 JSON"无法正确呈现 [英] Rendering 'as JSON' in Grails with conditional operator doesn't render correctly

问题描述

今天在 Grails 2.0.4 中尝试将对象列表呈现为 JSON 时遇到了这个奇怪的结果......(我知道我会后悔因为我眼皮底下的东西而问这个......更新 5/26，我的预测是正确的，见下文:-))

Came across this strange result today trying to render a list of objects as JSON in Grails 2.0.4...(i know i'm gonna regret asking this on account of something right under my nose...updated 5/26, my prediction was correct, see below :-))

这很好用；JSON 在浏览器中正确呈现...

This works fine; the JSON renders correctly in the browser...

def products = [] //ArrayList of Product objects from service       
def model = (products) ? [products:products] : [products:"No products found"] 
render model as JSON

...那么为什么这个没有 model 的缩短版本不起作用?

..so why doesn't this shortened version without model work?

def products = []       
render ((products) ? [products:products] : [products:"No products found"]) as JSON

上述代码的结果 JSON 作为单行文本输出，所以我怀疑它没有选择 as JSON，但它的括号正确，所以有什么关系?

The resulting JSON from the above code is output as a single line of text, so I suspect it's not picking up as JSON, but it's parenthesized correctly, so what's the deal?

['products':[com.test.domain.Product : null,com.test.domain.Product...]

['products':[com.test.domain.Product : null, com.test.domain.Product...]

推荐答案

这是 render 的正常行为.当您为 render 提供参数而没有像

This is a normal behavior of render. When you provide arguments to render without braces like

将模型渲染为 JSON

它进行了隐式调整，将 content-type 设置为 text/json.但是在后一种情况下，您在不知不觉中使 render 使用大括号，例如 [mark on the first括号 after render 使 render 使用正常的 render()]

It makes an implicit adjustment setting up the content-type to text/json. But in the later case, you have unknowingly made the render to use the braces like [mark on the first brace after render makes render use the normal render()]

将 ((products) ? [products:products] : [products:"No products found"]) 渲染为 JSON.

在上述情况下，您必须将命名参数传递给 render 提及 contentType、text 或 model、status 等.所以为了在浏览器/视图中将内联控制逻辑呈现为 JSON，您必须执行以下操作:

In the above case, you have to pass in the named parameters to render mentioning the contentType, text or model, status etc. So in order to render the inline control logic as JSON in browser/view you have to do like below:

render(contentType: "application/json", text: [products: (products ?: "No products found")] as JSON)

您也可以使用 content-type 作为 text/json.我更喜欢 application/json.

You can also use content-type as text/json. I prefer application/json.

更新
最简单的替代方法:
render([products: (products ?: "No products found")] as JSON)

这篇关于使用条件运算符在 Grails 中呈现“作为 JSON"无法正确呈现的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！