尝试将过滤器应用于充满对象的嵌套数组 [英] Trying to apply a filter to a nested array full of objects

问题描述

我有一个充满对象的资源数组.每个对象都有充满对象的类别数组.我试图将过滤器仅用于返回具有特定名称的类别对象的资源.我在嵌套数据对象时遇到了麻烦.

I have a resources array which is full of objects. Each object has categories array full of objects. I am trying to apply a filter to only return resources that have category objects of a specific name. I am having some trouble with the nesting of my data object.

以下是我正在使用的数据:

Here is the data I am working with:

const resources = [
  {
    title: 'Learn JS',
    categories: [
      {
        name: 'javascript'
      },
      {
        name: 'css'
      }
    ]
  },
  {
    title: 'Learn CSS',
    categories: [
      {
        name: 'css'
      }
    ]
  },
  {
    title: 'Learn other stuff',
    categories: [
      {
        name: 'jQuery'
      },
      {
        name: 'javascript'
      }
    ]
  },
  {
    title: 'Learn node',
    categories: [
      {
        name: 'node'
      }
    ]
  },
  {
    title: 'Learn React',
    categories: [
      {
        name: 'react'
      }
    ]
  },

];

这是我的两次尝试.两者都返回空数组.我尝试使用maps和filters是错误的. for loop是否必要?

Here are my two attempts. Both return empty arrays. Am I wrong to be trying to use maps and filters. Is a for loop necessary?

//GOAL: Return only the resources that have a category with name 'javascript'
const attemptOne = resources.filter((item) => {
  return item.categories.forEach((thing, index) => {
    return thing[index] === 'javascript'
  });
}).map((item) => {
  return item;
})

const attemptTwo = resources.filter((item) => {
  item.categories.filter((ci) => {
    return ci.name === 'javascript'
  }).map((nextItem) => {
    return nextItem;
  });
})

我已经绊了好一阵子了，我不确定我是否刚刚使它复杂化了.预先感谢！

I have been stumbling around with this for a while, and I am not sure if I am just over complicating it our what. Thanks in advance!

推荐答案

您可以在resources上使用filter.在过滤器内部，由于您已经知道对象具有类别，因此可以使用

You can use filter on resources. Inside the filter, since you already know that an object has categories, you can just use some to check if the category name you are looking for is included

const resources = [{
  title: 'Learn JS',
  categories: [{
    name: 'javascript'
  }, {
    name: 'css'
  }]
}, {
  title: 'Learn CSS',
  categories: [{
    name: 'css'
  }]
}, {
  title: 'Learn other stuff',
  categories: [{
    name: 'jQuery'
  }, {
    name: 'javascript'
  }]
}, {
  title: 'Learn node',
  categories: [{
    name: 'node'
  }]
}, {
  title: 'Learn React',
  categories: [{
    name: 'react'
  }]
}];

function filterViaCategory(arr, category) {
  return arr.filter(obj => obj.categories.some(cat => cat.name === category));
}

console.log(filterViaCategory(resources, 'javascript'));

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