javascript 如何将对象数组转换为 Lodash 中的对象？
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How to convert an array of objects to an object in Lodash?
提问by Stefan
I have this:
我有这个：
[ { list:
[ [Object],
[Object] ] },
{ head:
[ [Object],
[Object] ] }
]
And want to turn it into this:
并想把它变成这样：
{ list:
[ [Object],
[Object] ],
head: [ [Object],
[Object] ]
}
So an array of objects into an object. It would be great to achieve this with lodash.
于是一个对象数组变成了一个对象。用 lodash 实现这一点会很棒。
回答by djaszczurowski
_.reduce(array, function(memo, current) { return _.assign(memo, current) }, {})
回答by rcsole
I think an even shorter solution would be:
我认为一个更短的解决方案是：
Object.assign({}, ...array)
I know you asked for lodash, but it doesn't seem like you even need this way. Unless you want to use _.extend.
我知道您要求使用 lodash，但似乎您甚至不需要这种方式。除非你想使用_.extend.
回答by Johannes Fahrenkrug
To build on @rcsole's great answer, this works well:
为了建立在@rcsole 的伟大答案之上，这很有效：
states = [{
state: "NY",
name: "New York",
}, {
state: "AZ",
name: "Arizona",
}]
statesObj = Object.assign({}, ...states.map(state => {
return { [state.state]: state.name }
}))
Result:
结果：
{
AZ: "Arizona",
NY: "New York",
}
What's going on here?
这里发生了什么？
Let's break this up into multiple pieces:
让我们把它分解成多个部分：
// Step 1: Transform from [{state: "Foo", name: "Bar"}, ...] to [{Foo: "Bar"}, ...]
mappedStates = states.map(state => { return { [state.state]: state.name } })
// Step 2: Merge all the objects in that array into a single new object
statesObj = Object.assign({}, ...mappedStates)
Step 1 uses mapto iterate over every item in the array (every state object). mapexecutes a function for every stateobject and returns a new object with the state as the key and the name as the value. We need to surround state.statein brackets because it's a dynamic value in an object literal.
步骤 1 用于map迭代数组中的每个项目（每个状态对象）。map为每个state对象执行一个函数并返回一个以状态为键、名称为值的新对象。我们需要state.state用括号括起来，因为它是对象字面量中的动态值。
Step 2 uses Object.assignto merge all the new state objects in the mappedStatesarray into a new object (the first parameter, {}).
What are the three dots ...for? That's the spread operator. It takes every element in the mappedStatesarray and turns them into direct arguments of the Object.assignmethod.
步骤 2 用于Object.assign将mappedStates数组中的所有新状态对象合并为一个新对象（第一个参数，{}）。三个点...有什么用？那就是价差运算符。它获取mappedStates数组中的每个元素并将它们转换为Object.assign方法的直接参数。
This example makes it clear:
这个例子很清楚：
Object.assign({}, ...mappedStates)
is the same as
是相同的
Object.assign({}, {AZ: "Arizona"}, {NY: "New York"})
That's it!
而已！
回答by Adam Boduch
Here's a shorter version:
这是一个较短的版本：
_.transform(array, _.ary(_.extend, 2), {});
The transform()function is like reduce(), except it's not expecting you to return anything. Since extend()is altering it's first argument, we can just pass it straight to transform(). It's wrapped in ary()to make sure it only gets 2 arguments passed to it.
该变换（）函数就像是减少（） ，但它没有指望你任何回报。由于extend()正在改变它的第一个参数，我们可以直接将它传递给transform(). 它包含在ary() 中，以确保它只传递 2 个参数。
回答by udnisap
Use fromPairs on lodash 4. https://lodash.com/docs#fromPairs
使用fromPairs上lodash 4 https://lodash.com/docs#fromPairs
_.fromPairs([['fred', 30], ['barney', 40]]);
_.fromPairs([['fred', 30], ['barney', 40]]);
