Resolve ‘multi update only works with $ operators’ in MongoDb?

You can use $set operator for this. The syntax is as follows −

db.yourCollectionName.update({ }, {'$set': "yourFieldName": "yourValue" }, false, true);

To understand the above syntax, let us create a collection with the document. The query to create a collection with a document is as follows −

> db.unconditionalUpdatesDemo.insertOne({"ClientName":"Larry","ClientAge":24});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5c8eb7372f684a30fbdfd557")
}
> db.unconditionalUpdatesDemo.insertOne({"ClientName":"Mike","ClientAge":26});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5c8eb73f2f684a30fbdfd558")
}
> db.unconditionalUpdatesDemo.insertOne({"ClientName":"Sam","ClientAge":27});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5c8eb7462f684a30fbdfd559")
}
> db.unconditionalUpdatesDemo.insertOne({"ClientName":"Carol","ClientAge":29});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5c8eb7502f684a30fbdfd55a")
}

Display all documents from a collection with the help of find() method. The query is as follows −

> db.unconditionalUpdatesDemo.find().pretty();

The following is the output −

{
   "_id" : ObjectId("5c8eb7372f684a30fbdfd557"),
   "ClientName" : "Larry",
   "ClientAge" : 24
}
{
   "_id" : ObjectId("5c8eb73f2f684a30fbdfd558"),
   "ClientName" : "Mike",
   "ClientAge" : 26
}
{
   "_id" : ObjectId("5c8eb7462f684a30fbdfd559"),
   "ClientName" : "Sam",
   "ClientAge" : 27
}
{
   "_id" : ObjectId("5c8eb7502f684a30fbdfd55a"),
   "ClientName" : "Carol",
   "ClientAge" : 29
}

Here is the query for unconditional updates −

> db.unconditionalUpdatesDemo.update({ }, {'$set': {"ClientName": "Robert" }}, false, true);
WriteResult({ "nMatched" : 4, "nUpserted" : 0, "nModified" : 4 })

Let us check the documents from a collection with the help find(). The query is as follows −

> db.unconditionalUpdatesDemo.find().pretty();

The following is the output −

{
   "_id" : ObjectId("5c8eb7372f684a30fbdfd557"),
   "ClientName" : "Robert",
   "ClientAge" : 24
}
{
   "_id" : ObjectId("5c8eb73f2f684a30fbdfd558"),
   "ClientName" : "Robert",
   "ClientAge" : 26
}
{
   "_id" : ObjectId("5c8eb7462f684a30fbdfd559"),
   "ClientName" : "Robert",
   "ClientAge" : 27
}
{
   "_id" : ObjectId("5c8eb7502f684a30fbdfd55a"),
   "ClientName" : "Robert",
   "ClientAge" : 29
}