How to decrement like $dec?

Question

In the Meteor leaderboard example there is this line:

  Players.update(Session.get("selected_player"), {$inc: {score: 5}});

How can I gracefully decrement the same field? Sadly, there is no $dec.

Glazing

Answer 1

MongoDB allows you to increment by negative values:

$inc: {score: -1}

Antrorse

Answer 2

From the MongoDB docs (linked to from the Meteor docs): The $inc update operator accepts positive and negative values. A negative value effectively decrements the specified field.

http://docs.mongodb.org/manual/reference/operator/update/inc/

Kurtiskurtosis

Answer 3

You can apply this code:

$inc: {
  score: -1
}

apply negative values (-1, -3, -5 and so on ) for decrement value.

Hancock

Your answer could be improved by adding more information on what the code does and how it helps the OP. – Rianon

Answer 4

There is no need of something like $dec. A negative value effectively decrements the specified field. For example using (-value):

Players.update(Session.get("selected_player"), {$inc: {score: -value}});

Rai

Answer 5

Players.update(Session.get("selected_player"), {$inc: {score: -1}});

you can simply use negative value (ex : -1, -2, -3, .....) for decrement value in mongo collection

Melicent

Answer 6

Use the $inc update operator to decrement a field's value by providing a negative value.

db.products.updateOne(
  { name: "Laptop" },
  { $inc: { quantity: -5 } }
)

Kelso

Answer 7

JS

db.test.update({id: "zxf"}, {$inc: {intValue: NumberInt(-1)}});

Java

Update update = new Update().inc(field, -1);

Type

Generally, answers are much more helpful if they include an explanation of what the code is intended to do, and why that solves the problem without introducing others. – Painless