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Tolerim
21 days ago

How do I modify the value of an object in an array within NeDB?

As a Node.js web app developer using NeDB as a database, I need to update a specific value within an object that is stored in an array. Each entry in the NeDB database follows the template:

{username: username, password: password, achievements: [{name: name, type: type, achieved: achieved}, {name: name, type: type, achieved: achieved}, {name: name, type: type, achieved: achieved}]}

Suppose I want to update the achieved value of a specific achievement for a particular user, such as userOne. In that case, what approach should I take? I have attempted to use dot and object notation, but I have been unsuccessful in making any changes. Unfortunately, I couldn't find a solution to this problem. Any assistance would be hugely appreciated!

Answers(2)
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Vogi
20 days ago
Verified Answer
To update a specific value within an object that is stored in an array in NeDB, you can use the update method of NeDB. The update method takes two arguments: the first argument is the query object that specifies which documents to update, and the second argument is the update object that specifies how to update the documents. Here's an example of how you can use the update method to update the achieved value of a specific achievement for a particular user: 
db.update({ username: 'userOne', 'achievements.name': 'achievementOne' }, { $set: { 'achievements.$.achieved': true } }, {}, function (err, numReplaced) {
  // numReplaced = 1
  // The achievement with name 'achievementOne' for user with username 'userOne' has been updated.
});
In this example, we are updating the achieved value of the achievement with name 'achievementOne' for the user with username 'userOne'. The $set operator is used to set the new value of the achieved field. The $ positional operator is used to identify the element in the achievements array that matches the query. I hope this helps! Let me know if you have any further questions.

Sources

Update all the Values in an Object using JavaScript | bobbyhadzUpdate an Object's Property in Array of Objects in JSAdd Data into an Array in a State Object | PluralsightHow can I find and update values in an array of objects?How to update an array of object in javascript - Stack OverflowUpdating a value in a nested array of objects in React
avatar
Tolerim
21 days ago
To update a specific object value within an array using NeDB, you can make use of the $ operator which represents the index of the element in the array that you want to modify. Here's an example code snippet that demonstrates how you can achieve this: 
const Datastore = require('nedb');
const db = new Datastore({ filename: 'path/to/my/database.db', autoload: true });

const username = 'userOne';
const achievementName = 'one';
const newAchievementValue = true;

db.update(
  { username: username, 'achievements.name': achievementName },
  { $set: { 'achievements.$.achieved': newAchievementValue } },
  {}, (err, numReplaced) => {
    if(err) {
      console.error(err);
    } else if(numReplaced === 0) {
      console.error(`Achievement ${achievementName} not found for user ${username}`);
    } else {
      console.log(`Achievement ${achievementName} updated for user ${username}`);
    }
  }
);
In this code snippet, we first define the username, achievementName and newAchievementValue. We then call the update function on the db object, passing in the following arguments: - The first argument is a query that matches the user whose achievement we want to update. The $ operator is used to match the index of the achievement we want to update. - The second argument is an update modifier that sets the achieved value of the matched achievement to newAchievementValue. - The third argument is an empty object (i.e. {}) which specifies options for the update operation. In this case, we don't need to specify any options so we pass in an empty object. - Finally, we define a callback function that is called once the update operation is complete. The callback function takes two arguments: an err argument in case there was an error during the operation, and a numReplaced argument which represents the number of documents that were updated. Note that the above code assumes that there is only one achievement with a given name for each user. If multiple achievements with the same name are possible, you may need to modify the update query to include additional criteria to uniquely identify the achievement you want to update.
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