如何在setState中同时编辑数组中对象的特定字段

Question

我们如何在数组中创建object的特定字段？

state.items = [
     {id:0, left: 100, right: 100, classified: true},
     {id:1, left: 200, right: 300, classified: false}, 
]

// Edit left, right, classified with given values,
// where the object's id is equal to 1.
state.items = [
     {id:0, left: 100, right: 100, classified: true},
     {id:1, left: 300, right: 200, classified: true}, 
]

下面是函数内部的代码（问题）

//console.log(id) <- prints 1. We are modifying the second object in the array with id 1.

// iterate items array
let { items } = this.state;
for (var index in items) { 
  if(items[index].id === id) {
     // copy the whole object matching id is 1.
     var deep = _.cloneDeep(tag); 

     //Assign new values (newLeft: 300, newRight:200, newCalssified: true)
     deep.left = newLeft
     deep.right = newRight
     deep.classified = newClassified

    this.setState({
      // HERE IS THE QUESTION
      taggedClothes // how do we modify the object with id 1??
    })
  }
}

谢谢！！

Answer 1

您需要修改整个items数组，然后执行setstate来更新整个items数组。

const items = _.cloneDeep(this.state.items);

// Find index to modify
const index = items.findIndex(i => i.id === id);
items[index].left = newLeft;
items[index].right = newRight;
items[index].classified = newClassified;

this.setState({items});

编辑：如下文所述，突变状态并不总是一个好主意。我在开头添加了_.cloneDeep，但请查看此帖子以获得更多信息和其他选项：React：如何更新SetState上的State.Item[1]？（使用JSFiddle）