Class FieldMask (3.27.1) 

public sealed class FieldMask : IMessage<FieldMask>, IEquatable<FieldMask>, IDeepCloneable<FieldMask>, IBufferMessage, ICustomDiagnosticMessage, IMessage

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 the message in f.b.

Field masks are used to specify a subset of fields that should be returned 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 or sub-message is filtered by the API to only contain those fields as specified in the mask. For example, if the mask in the previous example 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 text output):

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

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

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

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

Field Masks in Update Operations

A field mask in update operations specifies which fields of the targeted resource are going to be updated. The API is required to only change the values of the fields as specified in the mask and leave the others untouched. If a resource is passed in to describe the updated values, the API ignores the values of all fields not covered by the mask.

If a repeated field is specified for an update operation, new values will be appended to the existing repeated field in the target resource. Note that a 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 an update operation, then new value will be merged into the existing sub-message in 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 for repeated and message fields.

In order to reset a field's value to the default, the field must be 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 default instance of the resource and set all fields in the mask, or do not provide a mask as described below.

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

As with get operations, the location of the resource which describes the updated values in the request message depends on the operation kind. In any case, the effect of the field mask is required to be honored by the API.

Considerations for HTTP REST

The HTTP kind of an update operation which uses a field mask must be 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 are separated by a comma. Fields name in each path are converted to/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 the following 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 in paths.

Field Mask Verification

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

Inheritance

object > FieldMask

Namespace

Google.Protobuf.WellKnownTypes

Assembly

Google.Protobuf.dll

Constructors

FieldMask()

public FieldMask()

FieldMask(FieldMask)

public FieldMask(FieldMask other)
Parameter
Name Description
other FieldMask

Fields

PathsFieldNumber

public const int PathsFieldNumber = 1

Field number for the "paths" field.

Field Value
Type Description
int

Properties

Descriptor

public static MessageDescriptor Descriptor { get; }
Property Value
Type Description
MessageDescriptor

Parser

public static MessageParser<FieldMask> Parser { get; }
Property Value
Type Description
MessageParserFieldMask

Paths

public RepeatedField<string> Paths { get; }

The set of field mask paths.

Property Value
Type Description
RepeatedFieldstring

Methods

CalculateSize()

public int CalculateSize()

Calculates the size of this message in Protocol Buffer wire format, in bytes.

Returns
Type Description
int

The number of bytes required to write this message to a coded output stream.

Clone()

public FieldMask Clone()

Creates a deep clone of this object.

Returns
Type Description
FieldMask

A deep clone of this object.

Equals(FieldMask)

public bool Equals(FieldMask other)
Parameter
Name Description
other FieldMask
Returns
Type Description
bool

Equals(object)

public override bool Equals(object other)
Parameter
Name Description
other object
Returns
Type Description
bool
Overrides

FromFieldNumbers<T>(IEnumerable<int>)

public static FieldMask FromFieldNumbers<T>(IEnumerable<int> fieldNumbers) where T : IMessage

Constructs a FieldMask from the passed field numbers.

Parameter
Name Description
fieldNumbers IEnumerableint
Returns
Type Description
FieldMask
Type Parameter
Name Description
T

The type to validate the field paths against.

FromFieldNumbers<T>(params int[])

public static FieldMask FromFieldNumbers<T>(params int[] fieldNumbers) where T : IMessage

Constructs a FieldMask from the passed field numbers.

Parameter
Name Description
fieldNumbers int
Returns
Type Description
FieldMask
Type Parameter
Name Description
T

The type to validate the field paths against.

FromString(string)

public static FieldMask FromString(string value)

Parses from a string to a FieldMask.

Parameter
Name Description
value string
Returns
Type Description
FieldMask

FromStringEnumerable<T>(IEnumerable<string>)

public static FieldMask FromStringEnumerable<T>(IEnumerable<string> paths) where T : IMessage

Constructs a FieldMask for a list of field paths in a certain type.

Parameter
Name Description
paths IEnumerablestring
Returns
Type Description
FieldMask
Type Parameter
Name Description
T

The type to validate the field paths against.

FromString<T>(string)

public static FieldMask FromString<T>(string value) where T : IMessage

Parses from a string to a FieldMask and validates all field paths.

Parameter
Name Description
value string
Returns
Type Description
FieldMask
Type Parameter
Name Description
T

The type to validate the field paths against.

GetHashCode()

public override int GetHashCode()
Returns
Type Description
int
Overrides

Intersection(FieldMask)

public FieldMask Intersection(FieldMask additionalMask)

Calculates the intersection of two FieldMasks.

Parameter
Name Description
additionalMask FieldMask
Returns
Type Description
FieldMask

IsValid(MessageDescriptor, FieldMask)

public static bool IsValid(MessageDescriptor descriptor, FieldMask fieldMask)

Checks whether paths in a given fields mask are valid.

Parameters
Name Description
descriptor MessageDescriptor
fieldMask FieldMask
Returns
Type Description
bool

IsValid(MessageDescriptor, string)

public static bool IsValid(MessageDescriptor descriptor, string path)

Checks whether paths in a given fields mask are valid.

Parameters
Name Description
descriptor MessageDescriptor
path string
Returns
Type Description
bool

IsValid<T>(FieldMask)

public static bool IsValid<T>(FieldMask fieldMask) where T : IMessage

Checks whether paths in a given fields mask are valid.

Parameter
Name Description
fieldMask FieldMask
Returns
Type Description
bool
Type Parameter
Name Description
T

The type to validate the field paths against.

IsValid<T>(string)

public static bool IsValid<T>(string path) where T : IMessage

Checks whether a given field path is valid.

Parameter
Name Description
path string
Returns
Type Description
bool
Type Parameter
Name Description
T

The type to validate the field paths against.

Merge(IMessage, IMessage)

public void Merge(IMessage source, IMessage destination)

Merges fields specified by this FieldMask from one message to another.

Parameters
Name Description
source IMessage
destination IMessage

Merge(IMessage, IMessage, MergeOptions)

public void Merge(IMessage source, IMessage destination, FieldMask.MergeOptions options)

Merges fields specified by this FieldMask from one message to another with the specified merge options.

Parameters
Name Description
source IMessage
destination IMessage
options FieldMaskMergeOptions

MergeFrom(CodedInputStream)

public void MergeFrom(CodedInputStream input)

Merges the data from the specified coded input stream with the current message.

Parameter
Name Description
input CodedInputStream
Remarks

See the user guide for precise merge semantics.

MergeFrom(FieldMask)

public void MergeFrom(FieldMask other)

Merges the given message into this one.

Parameter
Name Description
other FieldMask
Remarks

See the user guide for precise merge semantics.

Normalize()

public FieldMask Normalize()

Converts this FieldMask to its canonical form. In the canonical form of a FieldMask, all field paths are sorted alphabetically and redundant field paths are removed.

Returns
Type Description
FieldMask

ToDiagnosticString()

public string ToDiagnosticString()

Returns a string representation of this FieldMask for diagnostic purposes.

Returns
Type Description
string

A string representation of this value.
Remarks

Normally the returned value will be a JSON string value (including leading and trailing quotes) but when the value is non-normalized or out of range, a JSON object representation will be returned instead, including a warning. This is to avoid exceptions being thrown when trying to diagnose problems - the regular JSON formatter will still throw an exception for non-normalized values.

ToString()

public override string ToString()
Returns
Type Description
string
Overrides

Union(params FieldMask[])

public FieldMask Union(params FieldMask[] otherMasks)

Creates a union of two or more FieldMasks.

Parameter
Name Description
otherMasks FieldMask
Returns
Type Description
FieldMask

WriteTo(CodedOutputStream)

public void WriteTo(CodedOutputStream output)

Writes the data to the given coded output stream.

Parameter
Name Description
output CodedOutputStream

Coded output stream to write the data to. Must not be null.

Extension Methods