`db.update(query, update, options, callback)` will update all documents matching `query` according to the `update` rules:
* `query` is the same kind of finding query you use with `find` and `findOne`
* `update` specifies how the documents should be modified. It is either a new document which will replace the matched ones, or a set of modifiers. The available modifiers are `$set` to change a field's value and `$inc` to increment a field's value. You cannot use mixed updates with both modes (that doesn't make sense anyway)
* `options` is an object with two possible parameters: `multi` (defaults to `false`) which allows the modification of several documents if set to true, and `upsert` (defaults to `false`) if you want to insert a new document corresponding to the `update` rules if your `query` doesn't match anything
* `callback` (optional) signature: err, numReplaced, upsert. `numReplaced` is the number of documents replaced and `upsert` is set to true if the upsert mode was chosen and a document was inserted
* `update` specifies how the documents should be modified. It is either:
* A new document which will replace the matched ones
* A set of modifiers. The available modifiers are `$set` to change a field's value and `$inc` to increment a field's value. You cannot use mixed updates with both modes (that doesn't make sense anyway)
* `options` is an object with two possible parameters
* `multi` (defaults to `false`) which allows the modification of several documents if set to true
* `upsert` (defaults to `false`) if you want to insert a new document corresponding to the `update` rules if your `query` doesn't match anything
Louis Chatriot
12 years ago