# Class ProtoMessage<M> (3.7.0-rc)

3.7.0-rc 3.6.0 (latest) 3.5.0 3.4.0 3.3.0 3.2.0 2.48.0-rc 2.47.1 2.46.0 2.45.0 2.44.0 2.43.0 2.42.0 2.41.0 2.40.0 2.39.0 2.38.0 2.37.0 2.36.0 2.35.0 2.34.0 2.33.0 2.32.0 2.31.0 2.30.0 2.29.0 2.28.0 2.27.0 2.26.0 2.25.1 2.24.0 2.23.0 2.22.1 2.21.0 2.20.0 2.19.0 2.18.0 2.17.0 2.16.0 2.15.1 2.14.0 2.13.0 2.12.0 2.11.0 A representation of the Spanner PROTO type: a protobuf message.
A [`ProtoMessage`](https://docs.cloud.google.com/cpp/docs/reference/spanner/latest/classgoogle_1_1cloud_1_1spanner_1_1ProtoMessage)`<M>` can be implicitly constructed from and explicitly converted to an `M`. Values can be copied, assigned, and streamed.

A [`ProtoMessage`](https://docs.cloud.google.com/cpp/docs/reference/spanner/latest/classgoogle_1_1cloud_1_1spanner_1_1ProtoMessage)`<M>` can also be explicitly constructed from and converted to the `M` wire format, although this is intended for internal use only.

###### Example

Given a proto definition `message Mesg { string field = 1; }`:

    Mesg m;
    m.set_field("value");
    auto pm = spanner::ProtoMessage<Mesg>(m);
    assert(Mesg(pm).field() == "value");

## Constructors

### ProtoMessage()

The default value.

### ProtoMessage(M const \&)

Implicit construction from the message type.

| **Parameter** ||
|---|---|
| **Name** | **Description** |
| `m` | `M const &` |

### ProtoMessage(std::string)

Explicit construction from wire format.

| **Parameter** ||
|---|---|
| **Name** | **Description** |
| `serialized_message` | `std::string` |

## Operators

### operator message_type() const

Explicit conversion to the message type.

### operator std::string() const

Explicit conversion to wire format.

## Functions

### static TypeName()

The fully-qualified name of the message type, scope delimited by periods.

| **Returns** ||
|---|---|
| **Type** | **Description** |
| `std::string const &` |   |

## Type Aliases

### message_type

**Alias Of** : `M`