mgoutil

mgoutil

-- import "github.com/juju/mgoutil"

Package mgoutil provides helper functions relating to the mgo package.

Usage

type Update

type Update struct {
	// Set holds the fields to be set keyed by field name.
	Set map[string]interface{} `bson:"$set,omitempty"`

	// Unset holds the fields to be unset keyed by field name. Note that
	// the key values will be ignored.
	Unset map[string]interface{} `bson:"$unset,omitempty"`
}

Update represents a document update operation. When marshaled and provided to an update operation, it will set all the fields in Set and unset all the fields in Unset.

func AsUpdate

func AsUpdate(x interface{}) (Update, error)

AsUpdate returns the given object as an Update value holding all the fields of x, which must be acceptable to bson.Marshal, with zero-valued omitempty fields returned in Unset and others returned in Set. On success, the returned Set and Unset fields will always be non-nil, even when they contain no items.

Note that the _id field is omitted, as it is not possible to set this in an update operation.

This can be useful where an update operation is required to update only some subset of a given document without hard-coding all the struct fields into the update document.

For example,

u, err := AsUpdate(x)
if err != nil {
	...
}
coll.UpdateId(id, u)

is equivalent to:

coll.UpdateId(id, x)

as long as all the fields in the database document are mentioned in x. If there are other fields stored, they won't be affected.