如何更新 JSON 对象的字段？

Question

我正在使用 aeson 创建一个对象 JSON。如何给对象添加字段"email"？

> import Data.Aeson
> let alice = object ["name" .= "Alice", "age" .= 20]

我尝试使用 <> 但没有用

> import Data.Monoid
> alice <> object ["email" .= "alice@example.org"]

<interactive>:12:1: error:
    • No instance for (Monoid Value) arising from a use of ‘<>’
    • In the expression:
        alice <> object ["email" .= "alice@example.org"]
      In an equation for ‘it’:
          it = alice <> object ["email" .= "alice@example.org"]

Answer 1

在我之前的项目中，我曾经做过这样的事情：

import Data.Aeson
import Data.Text
import qualified Data.HashMap.Strict as HM

addJsonKey :: Text -> Value -> Value -> Value
addJsonKey key val (Object xs) = Object $ HM.insert key val xs
addJsonKey _ _ xs = xs

然后在 ghci:

λ> :set -XOverloadedStrings
λ> let alice = object ["name" .= "Alice", "age" .= 20]
λ> addJsonKey "email" (String "sibi@psibi.in") alice

让它工作的关键是理解类型 Value 是如何定义的：https://www.stackage.org/haddock/lts-12.1/aeson-1.3.1.1/Data-Aeson.html#t:Value

如何更新 JSON 对象的字段？

How to update a field of a JSON object?

haskell

aeson