Suppose I have these arrays:

const array1 = [
   {
      data: {
         site: {
            tag: {
               name: "Bikes", 
               posts: { ... }
            }
         }
      },
      errors: {}
   },
   { ... }   
]

const array2 = [
   {
      data: {
         category: {
            name: "Cars", 
            posts: { ... }
         }
      },
      errors: {}
   },
   { ... }   
]

const array3 = [
   {
      data: {
         posts: { ... }
      },
      errors: {}
   }, 
   { ... }  
]

What function can I use on array 1 and 2 so that I am always left with an array shaped like array 3? How can I always extract posts from data without knowing at what position it is in the nested object?

I've tried a few things with find or filter or recursive functions but I'm just no good at this, sorry. Hope somebody can help!

CodePudding user response：

If there might be only these two structures then you can manually extract posts based on whether data contains the site field or the category field.

const extractPosts = ({data, errors})=>{
    return {
        data: {
            posts: data.site ? data.site.tag.posts : data.category.posts
        },
        errors
    }
}

const unknownStructureArray = [{
    data: {
        site: {
            tag: {
                name: "Bikes",
                posts: {
                    type: 'primary'
                }
            }
        }
    },
    errors: {}
}, {
    data: {
        category: {
            name: "Cars",
            posts: {
                type: 'secondary'
            }
        }
    },
    errors: {}
}, ];

const array3 = unknownStructureArray.map(extractPosts);

CodePudding user response：

I'd suggest using a recursive approach, creating a function findPosts() that will walk through an object to find any posts.

We'd also create a convertArr() function that will map an input array to the desired shape:

const array1 = [
   {
      data: {
         site: {
            tag: {
               name: "Bikes", 
               posts: { 'post1': {}, 'post2': {} }
            }
         }
      },
      errors: {}
   },
   {
      data: {
         site: {
            tag: {
               name: "Stuff", 
               posts: { 'postA': {}, 'postB': {} }
            }
         }
      },
      errors: {}
   }
]

const array2 = [
   {
      data: {
         category: {
            name: "Cars", 
            posts: { post1: 'Some post', post2: 'Another post '}
         }
      },
      errors: {}
   }
]

function findPosts(input) { 
    for(let key in input) {
        if (key === 'posts') {
            return input[key];
        } else if (input[key] && (typeof(input[key]) === 'object')) {
            let posts = findPosts(input[key]);
            if (posts) {
                return posts;
            }
        }
    }
    return null;
}

function convertArr(arr) {
    return arr.map(el => { 
        return { 
            data: { posts: findPosts(el) },
            errors: el.errors
        };
    })
}

console.log('Array1:', convertArr(array1));
console.log('Array2:', convertArr(array2));

.as-console-wrapper { max-height: 100% !important; }