How to sort an array of object depending on value of a subfield?

user_12908033 0
Viewed 139

I have an array of objects called posts with a nested field answer. I have different conditions depending on which I need to sort my array.

Example array

let posts = [
  {
                        "_id": "610b806ec6386ffa276b6d1c",
                        "post": "CDat the difference between Equity and News channel?",
                        "answers": [
                            {
                                "_id": "613724604dd4b6f39b344b4c",
                                "type": "text",
                                
                            },
                            {
                                "_id": "6113c826a64da80fe48ab543",
                                "type": "video",
                                
                            },
                            {
                                "_id": "6113c740a64da80fe48ab534",
                                "type": "audio",
                                
                            },
                            {
                                "_id": "611135cf7497d70b6cc2c5e0",
                                "type": "video",
                               
                            }
                        ]
                    },
                    {
                        "_id": "611e14329ff0c343540ae10e",
                        "post": "How forex affects investment 6",
                        "answers": [
                            {
                                "_id": "61371b3a9bf14a39207fff8a",
                                "type": "video",
                                
                            },
                            {
                                "_id": "613719369507fd12f93e3c62",
                                "type": "text",
                                
                            },
                            {
                                "_id": "6135f28e29aeae3de45fc8c2",
                                "type": "text",
                                
                            },
                            {
                                "_id": "6135f07c831da33c28fc1cf6",
                                "type": "audio",
                                
                            },
                            {
                                "_id": "6135eb2d51a8830698d65cf3",
                                "type": "text",
                               
                            },
                           
                        ]
                    }

]

What I need to do is...I want to sort all the answers with type "video" to start and after that type "audio" and then type "text" answers like so


let posts = [
  {
                        "_id": "610b806ec6386ffa276b6d1c",
                        "post": "CDat the difference between Equity and News channel?",
                        "answers": [
                            {
                                "_id": "613724604dd4b6f39b344b4c",
                                "type": "video",
                                
                            },
                            {
                                "_id": "6113c826a64da80fe48ab543",
                                "type": "video",
                                
                            },
                            {
                                "_id": "6113c740a64da80fe48ab534",
                                "type": "audio",
                                
                            },
                            {
                                "_id": "611135cf7497d70b6cc2c5e0",
                                "type": "text",
                               
                            }
                        ]
                    },
                    {
                        "_id": "611e14329ff0c343540ae10e",
                        "post": "How forex affects investment 6",
                        "answers": [
                            {
                                "_id": "61371b3a9bf14a39207fff8a",
                                "type": "video",
                                
                            },
                            {
                                "_id": "613719369507fd12f93e3c62",
                                "type": "audio",
                                
                            },
                            {
                                "_id": "6135f28e29aeae3de45fc8c2",
                                "type": "text",
                                
                            },
                            {
                                "_id": "6135f07c831da33c28fc1cf6",
                                "type": "text",
                                
                            },
                            {
                                "_id": "6135eb2d51a8830698d65cf3",
                                "type": "text",
                               
                            },
                           
                        ]
                    }

]

Any help would be appreciated. Thank you

lodash arraylist sorting arrays javascript
4 Answers

You will need to loop through each entry in your posts array and sort the answers array inside each entry using a custom function.

The return value of the custom function (ele1, ele2) => {} should return a value > 0 if ele1 should be placed after ele2, a value < 0 if ele1 should be placed before ele2, and a value = 0 if they are considered equal.

const getRanking = (ele) => {
    if (ele.type == "video") return 1; 
    if (ele.type == "audio") return 2;
    if (ele.type == "text") return 3;
};

posts = posts.map(post => {
    post.answers.sort((ele1, ele2) => {
        return getRanking(ele1) - getRanking(ele2);
    });
    return post;
});
user_136907470
user_157784890

You need to add custom compare function.

This is the simplest solution for your question

let posts = [
  {
                        "_id": "610b806ec6386ffa276b6d1c",
                        "post": "CDat the difference between Equity and News channel?",
                        "answers": [
                            {
                                "_id": "613724604dd4b6f39b344b4c",
                                "type": "text",
                                
                            },
                            {
                                "_id": "6113c826a64da80fe48ab543",
                                "type": "video",
                                
                            },
                            {
                                "_id": "6113c740a64da80fe48ab534",
                                "type": "audio",
                                
                            },
                            {
                                "_id": "611135cf7497d70b6cc2c5e0",
                                "type": "video",
                               
                            }
                        ]
                    },
                    {
                        "_id": "611e14329ff0c343540ae10e",
                        "post": "How forex affects investment 6",
                        "answers": [
                            {
                                "_id": "61371b3a9bf14a39207fff8a",
                                "type": "video",
                                
                            },
                            {
                                "_id": "613719369507fd12f93e3c62",
                                "type": "text",
                                
                            },
                            {
                                "_id": "6135f28e29aeae3de45fc8c2",
                                "type": "text",
                                
                            },
                            {
                                "_id": "6135f07c831da33c28fc1cf6",
                                "type": "audio",
                                
                            },
                            {
                                "_id": "6135eb2d51a8830698d65cf3",
                                "type": "text",
                               
                            },
                           
                        ]
                    }

]


function type (t){
   if(t==="video") return 1;
   if(t==="audio") return 2;
   if(t==="text")return 3;
}
function comparotor(a, b){
  

  return type(a.type) - type(b.type)
}

posts.map(ele=>{
  ele.answers.sort(comparotor);
})

console.log(posts);

user_148086580

You can easily achieve the result by using JS only by passing the comparator function to sort function

"video" => "v"
"audio" => "a"
"text"  => "t"

You can use indexOf to check the first letter in a list of sorted letters(vat)

posts.map((o) =>o.answers.sort((a, b) => "vat".indexOf(a.type[0]) - "vat".indexOf(b.type[0])))


let posts = [
  {
    _id: "610b806ec6386ffa276b6d1c",
    post: "CDat the difference between Equity and News channel?",
    answers: [
      {
        _id: "613724604dd4b6f39b344b4c",
        type: "text",
      },
      {
        _id: "6113c826a64da80fe48ab543",
        type: "video",
      },
      {
        _id: "6113c740a64da80fe48ab534",
        type: "audio",
      },
      {
        _id: "611135cf7497d70b6cc2c5e0",
        type: "video",
      },
    ],
  },
  {
    _id: "611e14329ff0c343540ae10e",
    post: "How forex affects investment 6",
    answers: [
      {
        _id: "61371b3a9bf14a39207fff8a",
        type: "video",
      },
      {
        _id: "613719369507fd12f93e3c62",
        type: "text",
      },
      {
        _id: "6135f28e29aeae3de45fc8c2",
        type: "text",
      },
      {
        _id: "6135f07c831da33c28fc1cf6",
        type: "audio",
      },
      {
        _id: "6135eb2d51a8830698d65cf3",
        type: "text",
      },
    ],
  },
];

const result = posts.map((o) =>o.answers.sort((a, b) => "vat".indexOf(a.type[0]) - "vat".indexOf(b.type[0])));
console.log(result);

user_91534480
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