Replacing a whole block of data in JSON file

user_10247419 0
Viewed 232

I am looking for a way to replace a bunch of data in a JSON file without replacing another part of it:

{
  "task": [
    {
      "id": 5,
      "title": "dave",
      "description": "test"
    },
    {
      "id": 6,
      "title": "fddsfsd",
      "description": "fsdfsd"
    },
    {
      "id": 7,
      "title": "fddsfssdfsdfd",
      "description": "fsdfsd"
    },
    {
      "id": 8,
      "title": "fddsfssdfsdfd",
      "description": "fsdfsd"
    }
  ],
  "compteur": [
    {
      "id": 8
    }
  ]
}

I manage to get everything that is in between the brackets of "task" in a variable. My current issue is that I need to replace only what's inside the bracket and not affect the other parts of the file.

This is my code for retrieving the data of "tasks":

    function RemoveNode(idToDelete) {
      return jsonData.task.filter(function(emp) {
        if (emp.id == idToDelete) {
          return false;
        }
        return true;
      });
    }
    var newData = RemoveNode(idToDelete);
    arr1 = JSON.stringify(newData, null, 4);
    console.log("arr1", arr1);

The console.log gives me: 

arr1 [
    {
        "id": 5,
        "title": "dave",
        "description": "test"
    },
    {
        "id": 6,
        "title": "fddsfsd",
        "description": "fsdfsd"
    },
    {
        "id": 8,
        "title": "fddsfssdfsdfd",
        "description": "fsdfsd"
    }
]

I actually need to replace this in the original JSON File but I have absolutely no idea how to achieve this.

express node.js json javascript
2 Answers

You can use the spread operator, this will override the task data with your new filtered data

const removeNode = (idToDelete) => 
   jsonData.task.filter((emp) => emp.id != idToDelete);


const newData = RemoveNode(idToDelete);
const updatedJSONData = {...jsonData, task: newData};
user_100693130

If your JSON file is not too large, you could consider changing the task array in your JS object (once you've read or imported it into your program) and then re-writing the json file.

JSON file before the program runs:

{
  "task": [
    {
      "id": 5,
      "title": "dave",
      "description": "test"
    },
    {
      "id": 6,
      "title": "fddsfsd",
      "description": "fsdfsd"
    },
    {
      "id": 7,
      "title": "fddsfssdfsdfd",
      "description": "fsdfsd"
    },
    {
      "id": 8,
      "title": "fddsfssdfsdfd",
      "description": "fsdfsd"
    }
  ],
  "compteur": [
    {
      "id": 8
    }
  ]
}

Let's say we want to remove task objects with id=6. The code:

const myFileContents = require('./myFile.json');
const fs = require('fs');

const removeIdFromTasks = (taskList,idToRemove) => {
    return taskList.filter(task => task.id!=idToRemove);
}

const writeJsonFile = (fileName,content) => {
    fs.writeFile(fileName,content,(err) => {
        if(err){
            console.error(`Error in writing json file: ${e.message}`);
        } else {
            console.log(`File written`);
        }
    })
}

myFileContents.task = removeIdFromTasks(myFileContents.task,6);
writeJsonFile(`myFile.json`,JSON.stringify(myFileContents));

The same file after execution:

{
    "task": [
    {
        "id": 5,
        "title": "dave",
        "description": "test"
    },
    {
        "id": 7,
        "title": "fddsfssdfsdfd",
        "description": "fsdfsd"
    },
    {
        "id": 8,
        "title": "fddsfssdfsdfd",
        "description": "fsdfsd"
    }],
    "compteur": [
    {
        "id": 8
    }]
}
user_67183530
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