what is – Page 141

MongoDB $toDate

January 22, 2021January 19, 2021 by Ian

In MongoDB, the $toDate aggregation operator converts a value to a date

$toDate takes any valid expression. If the expression can’t be converted to a date, it returns an error. If the expression is null or missing, it returns null.

How the $set Update Operator Works in MongoDB

January 19, 2021 by Ian

The MongoDB $set update operator replaces the value of a field with the specified value.

It’s used in conjunction with update operations, for example when using the update() method to update a document.

MongoDB $mul

January 19, 2021 by Ian

MongoDB has a $mul field update operator that allows you to multiply a value by a specific amount.

If the field doesn’t already exist, it is created and its value is set to zero (0) using the same numeric type as the multiplier.

MongoDB $inc

January 18, 2021 by Ian

MongoDB has an $inc field update operator that allows you to increment a value by a specific amount.

You can use positive and negative values (i.e. to increment or decrement the value).

If the field doesn’t already exist, it is created with the specified value.

MongoDB $setOnInsert

January 18, 2021 by Ian

The MongoDB $setOnInsert field update operator can be used to insert a specific value during an upsert.

If an update operation results in a new document being inserted (i.e. an upsert), then the $setOnInsert operator takes effect, otherwise it has no effect.

MongoDB $max

January 17, 2021 by Ian

MongoDB has a $max operator that allows you to update the value of a field only if the specified value is greater than the current value of the field.

In other words, if the $max value is greater than the current value in the document, the $max value is used. Otherwise, the document’s value remains unchanged.

MongoDB $min

January 17, 2021 by Ian

MongoDB has a $min operator that allows you to update the value of a field only if the specified value is less than the current value of the field.

In other words, if the $min value is less than the current value in the document, the $min value is used. Otherwise, the document’s value remains unchanged.

MongoDB $pop

January 16, 2021 by Ian

In MongoDB, you can use the $pop operator to remove the first or last element from an array.

Use $pop in conjunction with a method such as update() to update the specified document with the change.

Use -1 to remove the first element, and 1 to remove the last.

MongoDB $pullAll

January 16, 2021 by Ian

In MongoDB, you can use the $pullAll operator to remove all instances of the specified values from an existing array.

Use $pullAll in conjunction with a method such as update(), updateOne(), or updateMany() to update the specified document/s with the change.

MongoDB $pull

January 15, 2021 by Ian

In MongoDB, you can use the $pull operator to remove values from an array.

Use $pull in conjunction with a method such as update() to update the specified document with the change.