var File_google_protobuf_field_mask_protoprotoreflect.FileDescriptor

typeFieldMask¶

type FieldMask struct {// The set of field mask paths.Paths []string `protobuf:"bytes,1,rep,name=paths,proto3" json:"paths,omitempty"`// contains filtered or unexported fields}

`FieldMask` represents a set of symbolic field paths, for example:

paths: "f.a"paths: "f.b.d"

Here `f` represents a field in some root message, `a` and `b`fields in the message found in `f`, and `d` a field found in themessage in `f.b`.

Field masks are used to specify a subset of fields that should bereturned by a get operation or modified by an update operation.Field masks also have a custom JSON encoding (see below).

Field Masks in Projections¶

When used in the context of a projection, a response message orsub-message is filtered by the API to only contain those fields asspecified in the mask. For example, if the mask in the previousexample is applied to a response message as follows:

f {  a : 22  b {    d : 1    x : 2  }  y : 13}z: 8

The result will not contain specific values for fields x,y and z(their value will be set to the default, and omitted in proto textoutput):

f {  a : 22  b {    d : 1  }}

A repeated field is not allowed except at the last position of apaths string.

If a FieldMask object is not present in a get operation, theoperation applies to all fields (as if a FieldMask of all fieldshad been specified).

Note that a field mask does not necessarily apply to thetop-level response message. In case of a REST get operation, thefield mask applies directly to the response, but in case of a RESTlist operation, the mask instead applies to each individual messagein the returned resource list. In case of a REST custom method,other definitions may be used. Where the mask applies will beclearly documented together with its declaration in the API. Inany case, the effect on the returned resource/resources is requiredbehavior for APIs.

Field Masks in Update Operations¶

A field mask in update operations specifies which fields of thetargeted resource are going to be updated. The API is requiredto only change the values of the fields as specified in the maskand leave the others untouched. If a resource is passed in todescribe the updated values, the API ignores the values of allfields not covered by the mask.

If a repeated field is specified for an update operation, new values willbe appended to the existing repeated field in the target resource. Note thata repeated field is only allowed in the last position of a `paths` string.

If a sub-message is specified in the last position of the field mask for anupdate operation, then new value will be merged into the existing sub-messagein the target resource.

For example, given the target message:

f {  b {    d: 1    x: 2  }  c: [1]}

And an update message:

f {  b {    d: 10  }  c: [2]}

then if the field mask is:

paths: ["f.b", "f.c"]

then the result will be:

f {  b {    d: 10    x: 2  }  c: [1, 2]}

An implementation may provide options to override this default behavior forrepeated and message fields.

In order to reset a field's value to the default, the field mustbe in the mask and set to the default value in the provided resource.Hence, in order to reset all fields of a resource, provide a defaultinstance of the resource and set all fields in the mask, or donot provide a mask as described below.

If a field mask is not present on update, the operation applies toall fields (as if a field mask of all fields has been specified).Note that in the presence of schema evolution, this may mean thatfields the client does not know and has therefore not filled intothe request will be reset to their default. If this is unwantedbehavior, a specific service may require a client to always specifya field mask, producing an error if not.

As with get operations, the location of the resource whichdescribes the updated values in the request message depends on theoperation kind. In any case, the effect of the field mask isrequired to be honored by the API.

## Considerations for HTTP REST

The HTTP kind of an update operation which uses a field mask mustbe set to PATCH instead of PUT in order to satisfy HTTP semantics(PUT must only be used for full updates).

JSON Encoding of Field Masks¶

In JSON, a field mask is encoded as a single string where paths areseparated by a comma. Fields name in each path are convertedto/from lower-camel naming conventions.

As an example, consider the following message declarations:

message Profile {  User user = 1;  Photo photo = 2;}message User {  string display_name = 1;  string address = 2;}

In proto a field mask for `Profile` may look as such:

mask {  paths: "user.display_name"  paths: "photo"}

In JSON, the same mask is represented as below:

{  mask: "user.displayName,photo"}

Field Masks and Oneof Fields¶

Field masks treat fields in oneofs just as regular fields. Consider thefollowing message:

message SampleMessage {  oneof test_oneof {    string name = 4;    SubMessage sub_message = 9;  }}

The field mask can be:

mask {  paths: "name"}

Or:

mask {  paths: "sub_message"}

Note that oneof type names ("test_oneof" in this case) cannot be used inpaths.

## Field Mask Verification

The implementation of any API method which has a FieldMask type field in therequest should verify the included field paths, and return an`INVALID_ARGUMENT` error if any path is unmappable.

func Intersect(mx *FieldMask, my *FieldMask, ms ...*FieldMask) *FieldMask

func New(mproto.Message, paths ...string) (*FieldMask,error)

func Union(mx *FieldMask, my *FieldMask, ms ...*FieldMask) *FieldMask

func (x *FieldMask) Append(mproto.Message, paths ...string)error

func (*FieldMask) Descriptor() ([]byte, []int)

func (x *FieldMask) GetPaths() []string

func (x *FieldMask) IsValid(mproto.Message)bool

func (x *FieldMask) Normalize()

func (*FieldMask) ProtoMessage()

func (x *FieldMask) ProtoReflect()protoreflect.Message

func (x *FieldMask) Reset()

func (x *FieldMask) String()string