Javascript: How to reduce json when consecutive key is the same?-CodePudding

I have a json where I need to reduce the items when they are of a type (isSender).
I need to reduce them when they are occurring consecutively.
The data can change.

The data looks like this:

 "messages": [
    { "content": ["Foo"], "isSender": true },
    { "content": ["Bar"], "isSender": true },
    { "content": ["Lorem"], "isSender": true },
    { "content": ["Ipsum"], "isSender": true },
    { "content": ["Dolor"], "isSender": false },
    { "content": ["Sit Amet"], "isSender": false },
    { "content": ["No"], "isSender": true }
  ]

I need the content to be an array of messages when the consecutive isSender key is the same. The output should look like this:

  "messages": [
    {
      "content": ["Foo", "Bar", "Lorem", "Ipsum"],
      "isSender": true
    },
    { "content": ["Dolor", "Sit amet"], "isSender": false },
    { "content": ["No"], "isSender": true }
  ]

So far I have tried looping through the message array and checking if next messages have the same isSender key. However this does not work for more than 2 messages.

let deleteIndex = [];
 for(let i = 0  ; i < messages.length - 1; i  ) {
        const currMs = messages[i];
        const nextMs = messages[i   1];
        if (nextMs.isSender == currMs.isSender) {
            currMs.content.push(nextMs)
            deleteIndex.push(i   1) // saving index to be deleted once for loop is done
        }
    }

Can someone give me a clue on how to work around this?

Thanks in advance.

CodePudding user response：

Use reduce(), on each iteration, we check if the last element in the result array has the same isSender value as the current object we're dealing with.

if (p.length && p.at(-1).isSender === c.isSender) {

So, if we already have something in the final array (p.length) AND the last isSender (p.at(-1).isSender) has the same value as the current isSender (c.isSender), append to that content list

Otherwise, add the entry, which is just the current object itself (return [ ...p, c ])

const data =  [
    { "content": ["Foo"], "isSender": true },
    { "content": ["Bar"], "isSender": true },
    { "content": ["Lorem"], "isSender": true },
    { "content": ["Ipsum"], "isSender": true },
    { "content": ["Dolor"], "isSender": false },
    { "content": ["Sit Amet"], "isSender": false },
    { "content": ["No"], "isSender": true }
  ];
  
const res = data.reduce((p, c) => {
    if (p.length && p.at(-1).isSender === c.isSender) {
        p.at(-1).content.push(...c.content);
        return p;
    }
    return [ ...p, c ];
}, [])

console.log(res);

[
  {
    "content": ["Foo", "Bar", "Lorem", "Ipsum"],
    "isSender": true
  },
  {
    "content": ["Dolor", "Sit Amet"],
    "isSender": false
  },
  {
    "content": ["No"],
    "isSender": true
  }
]

CodePudding user response：

you can try this

    JArray jArr = JObject.Parse(json)["messages"] as JArray;

    var noContent = jArr.Select(a => a)
                        .Where(a => string.Join(",", a["content"]) == "No")
                        .FirstOrDefault();

    jArr.Remove(noContent);

    var jObj = new JObject
    {
        ["messages"] = new JArray(jArr.GroupBy(x => x["isSender"])
                       .Select(g => new JObject
                       {
                           ["content"] = new JArray(g.SelectMany(y => y["content"])),
                           ["isSender"] = g.Key
                       }))
    };
    
    ((JArray)jObj["messages"]).Add(noContent);

    json = jObj.ToString();
    
    //or if you create a  Messages class
    
    Messages messages = jObj.ToObject<Messages>();

json output

{
  "messages": [
    {
      "content": [
        "Foo",
        "Bar",
        "Lorem",
        "Ipsum"
      ],
      "isSender": true
    },
    {
      "content": [
        "Dolor",
        "Sit Amet"
      ],
      "isSender": false
    },
    {
      "content": [
        "No"
      ],
      "isSender": true
    }
  ]
}