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https://github.com/bufbuild/protoc-gen-validate

Protocol Buffer Validation - Being replaced by github.com/bufbuild/protovalidate
https://github.com/bufbuild/protoc-gen-validate

constraints protoc protoc-plugin protocol-buffers validation

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Protocol Buffer Validation - Being replaced by github.com/bufbuild/protovalidate

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# [![](./.github/buf-logo.svg)][buf] protoc-gen-validate (PGV)



![License](https://img.shields.io/github/license/bufbuild/protoc-gen-validate?color=blue)

![Release](https://img.shields.io/github/v/release/bufbuild/protoc-gen-validate?include_prereleases)

![Slack](https://img.shields.io/badge/slack-buf-%23e01563)



> [!IMPORTANT]

> protoc-gen-validate (PGV) has reached a stable state and is in maintenance mode.

>

> We recommend that new and existing projects transition to using [`protovalidate`][pv].

> 

> Read [our blog post][pv-announce] if you want to learn more about the limitations of protoc-gen-validate and

> how we have designed [`protovalidate`][pv] to be better.



PGV is a protoc plugin to generate polyglot message validators. While protocol

buffers effectively guarantee the types of structured data, they cannot enforce

semantic rules for values. This plugin adds support to protoc-generated code to

validate such constraints.



Developers import the PGV extension and annotate the messages and fields in

their proto files with constraint rules:



```protobuf

syntax = "proto3";



package examplepb;



import "validate/validate.proto";



message Person {

  uint64 id = 1 [(validate.rules).uint64.gt = 999];



  string email = 2 [(validate.rules).string.email = true];



  string name = 3 [(validate.rules).string = {

    pattern:   "^[A-Za-z]+( [A-Za-z]+)*$",

    max_bytes: 256,

  }];



  Location home = 4 [(validate.rules).message.required = true];



  message Location {

    double lat = 1 [(validate.rules).double = {gte: -90,  lte: 90}];

    double lng = 2 [(validate.rules).double = {gte: -180, lte: 180}];

  }

}

```



Executing `protoc` with PGV and the target language's default plugin will

create `Validate` methods on the generated types:



```go

p := new(Person)



err := p.Validate() // err: Id must be greater than 999

p.Id = 1000



err = p.Validate() // err: Email must be a valid email address

p.Email = "[email protected]"



err = p.Validate() // err: Name must match pattern '^[A-Za-z]+( [A-Za-z]+)*$'

p.Name = "Protocol Buffer"



err = p.Validate() // err: Home is required

p.Home = &Location{37.7, 999}



err = p.Validate() // err: Home.Lng must be within [-180, 180]

p.Home.Lng = -122.4



err = p.Validate() // err: nil

```



## Usage



### Dependencies



- `go` toolchain (≥ v1.7)

- `protoc` compiler in `$PATH`

- `protoc-gen-validate` in `$PATH`

- official language-specific plugin for target language(s)

- **Only `proto3` syntax is currently supported.** `proto2` syntax support is

  planned.



### Installation



#### Download from GitHub Releases



Download assets from [GitHub Releases](https://github.com/bufbuild/protoc-gen-validate/releases) and unarchive them and add plugins into `$PATH`.



#### Build from source



```sh

# fetches this repo into $GOPATH

go get -d github.com/envoyproxy/protoc-gen-validate

```



> #### 💡 Yes, our go module path is `github.com/envoyproxy/protoc-gen-validate` **not** `bufbuild` this is intentional.

> Changing the module path is effectively creating a new, independent module. We

> would prefer not to break our users. The Go team are working on

> better `cmd/go`

> support for modules that change paths, but progress is slow. Until then, we

> will

> continue to use the `envoyproxy` module path.



```

git clone https://github.com/bufbuild/protoc-gen-validate.git

# installs PGV into $GOPATH/bin

cd protoc-gen-validate && make build

```



### Parameters



- **`lang`**: specify the target language to generate. Currently, the only

  supported options are:

    - `go`

    - `cc` for c++ (partially implemented)

    - `java`

- Note: Python works via runtime code generation. There's no compile-time

  generation. See the Python section for details.



### Examples



#### Go



Go generation should occur into the same output path as the official plugin. For

a proto file `example.proto`, the corresponding validation code is generated

into `../generated/example.pb.validate.go`:



```sh

protoc \

  -I . \

  -I path/to/validate/ \

  --go_out=":../generated" \

  --validate_out="lang=go:../generated" \

  example.proto

```



All messages generated include the following methods:



- `Validate() error` which returns the first error encountered during

  validation.

- `ValidateAll() error` which returns all errors encountered during validation.



PGV requires no additional runtime dependencies from the existing generated

code.



**Note**: by default **example.pb.validate.go** is nested in a directory

structure that matches your `option go_package` name. You can change this using

the protoc parameter `paths=source_relative:.`, as like `--validate_out="lang=go,paths=source_relative:../generated"`. Then `--validate_out` will

output the file where it is expected. See Google's protobuf documentation

or [packages and input paths](https://github.com/golang/protobuf#packages-and-input-paths)

or [parameters](https://github.com/golang/protobuf#parameters) for more

information.



There's also support for the `module=example.com/foo`

flag [described here](https://developers.google.com/protocol-buffers/docs/reference/go-generated#invocation)

.



With newer Buf CLI versions (>v1.9.0), you can use the new plugin key instead of using the `protoc` command directly:



```

# buf.gen.yaml



version: v1

plugins:

  - plugin: buf.build/bufbuild/validate-go

    out: gen

```



```

# proto/buf.yaml



version: v1

deps:

  - buf.build/envoyproxy/protoc-gen-validate

```



#### Java



Java generation is integrated with the existing protobuf toolchain for java

projects. For Maven projects, add the

following to your pom.xml or build.gradle.



```xml



    

        build.buf.protoc-gen-validate

        pgv-java-stub

        ${pgv.version}

    



    

        kr.motd.maven

        os-maven-plugin

        1.4.1.Final

    



    

        org.xolstice.maven.plugins

        protobuf-maven-plugin

        0.6.1

        

            

                com.google.protobuf:protoc:${protoc.version}:exe:${os.detected.classifier}

            

        

        

            

                protoc-java-pgv

                

                    compile-custom

                

                

                    lang=java

                    java-pgv

                    

                        build.buf.protoc-gen-validate:protoc-gen-validate:${pgv.version}:exe:${os.detected.classifier}

                    

                

            

        

    



```



```gradle

plugins {

    ...

    id "com.google.protobuf" version "${protobuf.version}"

    ...

}



protobuf {

    protoc {

        artifact = "com.google.protobuf:protoc:${protoc.version}"

    }



    plugins {

        javapgv {

            artifact = "build.buf.protoc-gen-validate:protoc-gen-validate:${pgv.version}"

        }

    }



    generateProtoTasks {

        all()*.plugins {

            javapgv {

                option "lang=java"

            }

        }

    }

}

```



```java

// Create a validator index that reflectively loads generated validators

ValidatorIndex index = new ReflectiveValidatorIndex();

// Assert that a message is valid

index.validatorFor(message.getClass()).assertValid(message);



// Create a gRPC client and server interceptor to automatically validate messages (requires pgv-java-grpc module)

clientStub = clientStub.withInterceptors(new ValidatingClientInterceptor(index));

serverBuilder.addService(ServerInterceptors.intercept(svc, new ValidatingServerInterceptor(index)));

```



#### Python



The python implementation works via JIT code generation. In other words,

the `validate(msg)` function is written

on-demand and [exec-ed](https://docs.python.org/3/library/functions.html#exec).

An LRU-cache improves performance by

storing generated functions per descriptor.



The python package is available

on [PyPI](https://pypi.org/project/protoc-gen-validate).



To run `validate()`, do the following:



```python

from entities_pb2 import Person

from protoc_gen_validate.validator import validate, ValidationFailed



p = Person(first_name="Foo", last_name="Bar", age=42)

try:

    validate(p)

except ValidationFailed as err:

    print(err)

```



You can view what code has been generated by using the `print_validate()`

function.



## Constraint Rules



[The provided constraints](validate/validate.proto) are modeled largerly after

those in JSON Schema. PGV rules can be mixed for the same field; the plugin

ensures the rules applied to a field cannot contradict before code generation.



Check the [constraint rule comparison matrix](rule_comparison.md) for

language-specific constraint capabilities.



### Numerics



> All numeric types (`float`, `double`, `int32`, `int64`, `uint32`, `uint64`

> , `sint32`, `sint64`, `fixed32`, `fixed64`, `sfixed32`, `sfixed64`) share the

> same rules.



- **const**: the field must be _exactly_ the specified value.



  ```protobuf

  // x must equal 1.23 exactly

  float x = 1 [(validate.rules).float.const = 1.23];

  ```



- **lt/lte/gt/gte**: these inequalities (`<`, `<=`, `>`, `>=`, respectively)

  allow for deriving ranges in which the field must reside.



  ```protobuf

  // x must be less than 10

  int32 x = 1 [(validate.rules).int32.lt = 10];



  // x must be greater than or equal to 20

  uint64 x = 1 [(validate.rules).uint64.gte = 20];



  // x must be in the range [30, 40)

  fixed32 x = 1 [(validate.rules).fixed32 = {gte:30, lt: 40}];

  ```



  Inverting the values of `lt(e)` and `gt(e)` is valid and creates an exclusive

  range.



  ```protobuf

  // x must be outside the range [30, 40)

  double x = 1 [(validate.rules).double = {lt:30, gte:40}];

  ```



- **in/not_in**: these two rules permit specifying allow/denylists for the

  values of a field.



  ```protobuf

  // x must be either 1, 2, or 3

  uint32 x = 1 [(validate.rules).uint32 = {in: [1,2,3]}];



  // x cannot be 0 nor 0.99

  float x = 1 [(validate.rules).float = {not_in: [0, 0.99]}];

  ```



- **ignore_empty**: this rule specifies that if field is empty or set to the

  default value, to ignore any validation rules. These are typically useful

  where being able to unset a field in an update request, or to skip validation

  for optional fields where switching to WKTs is not feasible.



  ```protobuf

  uint32 x = 1 [(validate.rules).uint32 = {ignore_empty: true, gte: 200}];

  ```



### Bools



- **const**: the field must be _exactly_ the specified value.



  ```protobuf

  // x must be set to true

  bool x = 1 [(validate.rules).bool.const = true];



  // x cannot be set to true

  bool x = 1 [(validate.rules).bool.const = false];

  ```



### Strings



- **const**: the field must be _exactly_ the specified value.



  ```protobuf

  // x must be set to "foo"

  string x = 1 [(validate.rules).string.const = "foo"];

  ```



- **len/min_len/max_len**: these rules constrain the number of characters (

  Unicode code points) in the field. Note that the number of characters may

  differ from the number of bytes in the string. The string is considered as-is,

  and does not normalize.



  ```protobuf

  // x must be exactly 5 characters long

  string x = 1 [(validate.rules).string.len = 5];



  // x must be at least 3 characters long

  string x = 1 [(validate.rules).string.min_len = 3];



  // x must be between 5 and 10 characters, inclusive

  string x = 1 [(validate.rules).string = {min_len: 5, max_len: 10}];

  ```



- **min_bytes/max_bytes**: these rules constrain the number of bytes in the

  field.



  ```protobuf

  // x must be at most 15 bytes long

  string x = 1 [(validate.rules).string.max_bytes = 15];



  // x must be between 128 and 1024 bytes long

  string x = 1 [(validate.rules).string = {min_bytes: 128, max_bytes: 1024}];

  ```



- **pattern**: the field must match the specified [RE2-compliant][re2] regular

  expression. The included expression should elide any delimiters (ie, `/\d+/`

  should just be `\d+`).



  ```protobuf

  // x must be a non-empty, case-insensitive hexadecimal string

  string x = 1 [(validate.rules).string.pattern = "(?i)^[0-9a-f]+$"];

  ```



- **prefix/suffix/contains/not_contains**: the field must contain the specified

  substring in an optionally explicit location, or not contain the specified

  substring.



  ```protobuf

  // x must begin with "foo"

  string x = 1 [(validate.rules).string.prefix = "foo"];



  // x must end with "bar"

  string x = 1 [(validate.rules).string.suffix = "bar"];



  // x must contain "baz" anywhere inside it

  string x = 1 [(validate.rules).string.contains = "baz"];



  // x cannot contain "baz" anywhere inside it

  string x = 1 [(validate.rules).string.not_contains = "baz"];



  // x must begin with "fizz" and end with "buzz"

  string x = 1 [(validate.rules).string = {prefix: "fizz", suffix: "buzz"}];



  // x must end with ".proto" and be less than 64 characters

  string x = 1 [(validate.rules).string = {suffix: ".proto", max_len:64}];

  ```



- **in/not_in**: these two rules permit specifying allow/denylists for the

  values of a field.



  ```protobuf

  // x must be either "foo", "bar", or "baz"

  string x = 1 [(validate.rules).string = {in: ["foo", "bar", "baz"]}];



  // x cannot be "fizz" nor "buzz"

  string x = 1 [(validate.rules).string = {not_in: ["fizz", "buzz"]}];

  ```



- **ignore_empty**: this rule specifies that if field is empty or set to the

  default value, to ignore any validation rules. These are typically useful

  where being able to unset a field in an update request, or to skip validation

  for optional fields where switching to WKTs is not feasible.



  ```protobuf

  string CountryCode = 1 [(validate.rules).string = {ignore_empty: true, len: 2}];

  ```



- **well-known formats**: these rules provide advanced constraints for common

  string patterns. These constraints will typically be more permissive and

  performant than equivalent regular expression patterns, while providing more

  explanatory failure descriptions.



  ```protobuf

  // x must be a valid email address (via RFC 5322)

  string x = 1 [(validate.rules).string.email = true];



  // x must be a valid address (IP or Hostname).

  string x = 1 [(validate.rules).string.address = true];



  // x must be a valid hostname (via RFC 1034)

  string x = 1 [(validate.rules).string.hostname = true];



  // x must be a valid IP address (either v4 or v6)

  string x = 1 [(validate.rules).string.ip = true];



  // x must be a valid IPv4 address

  // eg: "192.168.0.1"

  string x = 1 [(validate.rules).string.ipv4 = true];



  // x must be a valid IPv6 address

  // eg: "fe80::3"

  string x = 1 [(validate.rules).string.ipv6 = true];



  // x must be a valid absolute URI (via RFC 3986)

  string x = 1 [(validate.rules).string.uri = true];



  // x must be a valid URI reference (either absolute or relative)

  string x = 1 [(validate.rules).string.uri_ref = true];



  // x must be a valid UUID (via RFC 4122)

  string x = 1 [(validate.rules).string.uuid = true];



  // x must conform to a well known regex for HTTP header names (via RFC 7230)

  string x = 1 [(validate.rules).string.well_known_regex = HTTP_HEADER_NAME]



  // x must conform to a well known regex for HTTP header values (via RFC 7230)

  string x = 1 [(validate.rules).string.well_known_regex = HTTP_HEADER_VALUE];



  // x must conform to a well known regex for headers, disallowing \r\n\0 characters.

  string x = 1 [(validate.rules).string {well_known_regex: HTTP_HEADER_VALUE, strict: false}];

  ```



### Bytes



> Literal values should be expressed with strings, using escaping where

> necessary.



- **const**: the field must be _exactly_ the specified value.



  ```protobuf

  // x must be set to "foo" ("\x66\x6f\x6f")

  bytes x = 1 [(validate.rules).bytes.const = "foo"];



  // x must be set to "\xf0\x90\x28\xbc"

  bytes x = 1 [(validate.rules).bytes.const = "\xf0\x90\x28\xbc"];

  ```



- **len/min_len/max_len**: these rules constrain the number of bytes in the

  field.



  ```protobuf

  // x must be exactly 3 bytes

  bytes x = 1 [(validate.rules).bytes.len = 3];



  // x must be at least 3 bytes long

  bytes x = 1 [(validate.rules).bytes.min_len = 3];



  // x must be between 5 and 10 bytes, inclusive

  bytes x = 1 [(validate.rules).bytes = {min_len: 5, max_len: 10}];

  ```



- **pattern**: the field must match the specified [RE2-compliant][re2] regular

  expression. The included expression should elide any delimiters (ie, `/\d+/`

  should just be `\d+`).



  ```protobuf

  // x must be a non-empty, ASCII byte sequence

  bytes x = 1 [(validate.rules).bytes.pattern = "^[\x00-\x7F]+$"];

  ```



- **prefix/suffix/contains**: the field must contain the specified byte sequence

  in an optionally explicit location.



  ```protobuf

  // x must begin with "\x99"

  bytes x = 1 [(validate.rules).bytes.prefix = "\x99"];



  // x must end with "buz\x7a"

  bytes x = 1 [(validate.rules).bytes.suffix = "buz\x7a"];



  // x must contain "baz" anywhere inside it

  bytes x = 1 [(validate.rules).bytes.contains = "baz"];

  ```



- **in/not_in**: these two rules permit specifying allow/denylists for the

  values of a field.



  ```protobuf

  // x must be either "foo", "bar", or "baz"

  bytes x = 1 [(validate.rules).bytes = {in: ["foo", "bar", "baz"]}];



  // x cannot be "fizz" nor "buzz"

  bytes x = 1 [(validate.rules).bytes = {not_in: ["fizz", "buzz"]}];

  ```



- **ignore_empty**: this rule specifies that if field is empty or set to the

  default value, to ignore any validation rules. These are typically useful

  where being able to unset a field in an update request, or to skip validation

  for optional fields where switching to WKTs is not feasible.



  ```protobuf

  bytes x = 1 [(validate.rules).bytes = {ignore_empty: true, in: ["foo", "bar", "baz"]}];

  ```



- **well-known formats**: these rules provide advanced constraints for common

  patterns. These constraints will typically be more permissive and performant

  than equivalent regular expression patterns, while providing more explanatory

  failure descriptions.



  ```protobuf

  // x must be a valid IP address (either v4 or v6) in byte format

  bytes x = 1 [(validate.rules).bytes.ip = true];



  // x must be a valid IPv4 address in byte format

  // eg: "\xC0\xA8\x00\x01"

  bytes x = 1 [(validate.rules).bytes.ipv4 = true];



  // x must be a valid IPv6 address in byte format

  // eg: "\x20\x01\x0D\xB8\x85\xA3\x00\x00\x00\x00\x8A\x2E\x03\x70\x73\x34"

  bytes x = 1 [(validate.rules).bytes.ipv6 = true];

  ```



### Enums



> All literal values should use the numeric (int32) value as defined in the enum

> descriptor.



The following examples use this `State` enum



```protobuf

enum State {

  INACTIVE = 0;

  PENDING = 1;

  ACTIVE = 2;

}

```



- **const**: the field must be _exactly_ the specified value.



  ```protobuf

  // x must be set to ACTIVE (2)

  State x = 1 [(validate.rules).enum.const = 2];

  ```



- **defined_only**: the field must be one of the specified values in the enum

  descriptor.



  ```protobuf

  // x can only be INACTIVE, PENDING, or ACTIVE

  State x = 1 [(validate.rules).enum.defined_only = true];

  ```



- **in/not_in**: these two rules permit specifying allow/denylists for the

  values of a field.



  ```protobuf

  // x must be either INACTIVE (0) or ACTIVE (2)

  State x = 1 [(validate.rules).enum = {in: [0,2]}];



  // x cannot be PENDING (1)

  State x = 1 [(validate.rules).enum = {not_in: [1]}];

  ```



### Messages



> If a field contains a message and the message has been generated with PGV,

> validation will be performed recursively. Message's not generated with PGV are

> skipped.



```protobuf

// if Person was generated with PGV and x is set,

// x's fields will be validated.

    Person x = 1;

```



- **skip**: this rule specifies that the validation rules of this field should

  not be evaluated.



  ```protobuf

  // The fields on Person x will not be validated.

  Person x = 1 [(validate.rules).message.skip = true];

  ```



- **required**: this rule specifies that the field cannot be unset.



  ```protobuf

  // x cannot be unset

  Person x = 1 [(validate.rules).message.required = true];



  // x cannot be unset, but the validations on x will not be performed

  Person x = 1 [(validate.rules).message = {required: true, skip: true}];

  ```



### Repeated



- **min_items/max_items**: these rules control how many elements are contained

  in the field



  ```protobuf

  // x must contain at least 3 elements

  repeated int32 x = 1 [(validate.rules).repeated.min_items = 3];



  // x must contain between 5 and 10 Persons, inclusive

  repeated Person x = 1 [(validate.rules).repeated = {min_items: 5, max_items: 10}];



  // x must contain exactly 7 elements

  repeated double x = 1 [(validate.rules).repeated = {min_items: 7, max_items: 7}];

  ```



- **unique**: this rule requires that all elements in the field must be unique.

  This rule does not support repeated messages.



  ```protobuf

  // x must contain unique int64 values

  repeated int64 x = 1 [(validate.rules).repeated.unique = true];

  ```



- **items**: this rule specifies constraints that should be applied to each

  element in the field. Repeated message fields also have their validation rules

  applied unless `skip` is specified on this constraint.



  ```protobuf

  // x must contain positive float values

  repeated float x = 1 [(validate.rules).repeated.items.float.gt = 0];



  // x must contain Persons but don't validate them

  repeated Person x = 1 [(validate.rules).repeated.items.message.skip = true];

  ```



- **ignore_empty**: this rule specifies that if field is empty or set to the

  default value, to ignore any validation rules. These are typically useful

  where being able to unset a field in an update request, or to skip validation

  for optional fields where switching to WKTs is not feasible.



  ```protobuf

  repeated int64 x = 1 [(validate.rules).repeated = {ignore_empty: true, items: {int64: {gt: 200}}}];

  ```



### Maps



- **min_pairs/max_pairs**: these rules control how many KV pairs are contained

  in this field



  ```protobuf

  // x must contain at least 3 KV pairs

  map x = 1 [(validate.rules).map.min_pairs = 3];



  // x must contain between 5 and 10 KV pairs

  map x = 1 [(validate.rules).map = {min_pairs: 5, max_pairs: 10}];



  // x must contain exactly 7 KV pairs

  map x = 1 [(validate.rules).map = {min_pairs: 7, max_pairs: 7}];

  ```



- **no_sparse**: for map fields with message values, setting this rule to true

  disallows keys with unset values.



  ```protobuf

  // all values in x must be set

  map x = 1 [(validate.rules).map.no_sparse = true];

  ```



- **keys**: this rule specifies constraints that are applied to the keys in the

  field.



  ```protobuf

  // x's keys must all be negative

   x = [(validate.rules).map.keys.sint32.lt = 0];

  ```



- **values**: this rule specifies constraints that are be applied to each value

  in the field. Repeated message fields also have their validation rules applied

  unless `skip` is specified on this constraint.



  ```protobuf

  // x must contain strings of at least 3 characters

  map x = 1 [(validate.rules).map.values.string.min_len = 3];



  // x must contain Persons but doesn't validate them

  map x = 1 [(validate.rules).map.values.message.skip = true];

  ```



- **ignore_empty**: this rule specifies that if field is empty or set to the

  default value, to ignore any validation rules. These are typically useful

  where being able to unset a field in an update request, or to skip validation

  for optional fields where switching to WKTs is not feasible.



  ```protobuf

  map x = 1 [(validate.rules).map = {ignore_empty: true, values: {string: {min_len: 3}}}];

  ```



### Well-Known Types (WKTs)



A set of [WKTs][wkts] are packaged with protoc and common message patterns

useful in many domains.



#### Scalar Value Wrappers



In the `proto3` syntax, there is no way of distinguishing between unset and the

zero value of a scalar field. The value WKTs permit this differentiation by

wrapping them in a message. PGV permits using the same scalar rules that the

wrapper encapsulates.



```protobuf

// if it is set, x must be greater than 3

    google.protobuf.Int32Value x = 1 [(validate.rules).int32.gt = 3];

```



Message Rules can also be used with scalar Well-Known Types (WKTs):



```protobuf

// Ensures that if a value is not set for age, it would not pass the validation despite its zero value being 0.

message X {google.protobuf.Int32Value age = 1 [(validate.rules).int32.gt = -1, (validate.rules).message.required = true];}

```



#### Anys



- **required**: this rule specifies that the field must be set



  ```protobuf

  // x cannot be unset

  google.protobuf.Any x = 1 [(validate.rules).any.required = true];

  ```



- **in/not_in**: these two rules permit specifying allow/denylists for

  the `type_url` value in this field. Consider using a `oneof` union instead

  of `in` if possible.



  ```protobuf

  // x must not be the Duration or Timestamp WKT

  google.protobuf.Any x = 1 [(validate.rules).any = {not_in: [

      "type.googleapis.com/google.protobuf.Duration",

      "type.googleapis.com/google.protobuf.Timestamp"

    ]}];

  ```



#### Durations



- **required**: this rule specifies that the field must be set



  ```protobuf

  // x cannot be unset

  google.protobuf.Duration x = 1 [(validate.rules).duration.required = true];

  ```



- **const**: the field must be _exactly_ the specified value.



  ```protobuf

  // x must equal 1.5s exactly

  google.protobuf.Duration x = 1 [(validate.rules).duration.const = {

      seconds: 1,

      nanos:   500000000

    }];

  ```



- **lt/lte/gt/gte**: these inequalities (`<`, `<=`, `>`, `>=`, respectively)

  allow for deriving ranges in which the field must reside.



  ```protobuf

  // x must be less than 10s

  google.protobuf.Duration x = 1 [(validate.rules).duration.lt.seconds = 10];



  // x must be greater than or equal to 20ns

  google.protobuf.Duration x = 1 [(validate.rules).duration.gte.nanos = 20];



  // x must be in the range [0s, 1s)

  google.protobuf.Duration x = 1 [(validate.rules).duration = {

      gte: {},

      lt:  {seconds: 1}

    }];

  ```



  Inverting the values of `lt(e)` and `gt(e)` is valid and creates an exclusive

  range.



  ```protobuf

  // x must be outside the range [0s, 1s)

  google.protobuf.Duration x = 1 [(validate.rules).duration = {

      lt:  {},

      gte: {seconds: 1}

    }];

  ```



- **in/not_in**: these two rules permit specifying allow/denylists for the

  values of a field.



  ```protobuf

  // x must be either 0s or 1s

  google.protobuf.Duration x = 1 [(validate.rules).duration = {in: [

      {},

      {seconds: 1}

    ]}];



  // x cannot be 20s nor 500ns

  google.protobuf.Duration x = 1 [(validate.rules).duration = {not_in: [

      {seconds: 20},

      {nanos: 500}

    ]}];

  ```



#### Timestamps



- **required**: this rule specifies that the field must be set



  ```protobuf

  // x cannot be unset

  google.protobuf.Timestamp x = 1 [(validate.rules).timestamp.required = true];

  ```



- **const**: the field must be _exactly_ the specified value.



  ```protobuf

  // x must equal 2009/11/10T23:00:00.500Z exactly

  google.protobuf.Timestamp x = 1 [(validate.rules).timestamp.const = {

      seconds: 63393490800,

      nanos:   500000000

    }];

  ```



- **lt/lte/gt/gte**: these inequalities (`<`, `<=`, `>`, `>=`, respectively)

  allow for deriving ranges in which the field must reside.



  ```protobuf

  // x must be less than the Unix Epoch

  google.protobuf.Timestamp x = 1 [(validate.rules).timestamp.lt.seconds = 0];



  // x must be greater than or equal to 2009/11/10T23:00:00Z

  google.protobuf.Timestamp x = 1 [(validate.rules).timestamp.gte.seconds = 63393490800];



  // x must be in the range [epoch, 2009/11/10T23:00:00Z)

  google.protobuf.Timestamp x = 1 [(validate.rules).timestamp = {

      gte: {},

      lt:  {seconds: 63393490800}

    }];

  ```



  Inverting the values of `lt(e)` and `gt(e)` is valid and creates an exclusive

  range.



  ```protobuf

  // x must be outside the range [epoch, 2009/11/10T23:00:00Z)

  google.protobuf.Timestamp x = 1 [(validate.rules).timestamp = {

      lt:  {},

      gte: {seconds: 63393490800}

    }];

  ```



- **lt_now/gt_now**: these inequalities allow for ranges relative to the current

  time. These rules cannot be used with the absolute rules above.



  ```protobuf

  // x must be less than the current timestamp

  google.protobuf.Timestamp x = 1 [(validate.rules).timestamp.lt_now = true];

  ```

- **within**: this rule specifies that the field's value should be within a

  duration of the current time. This rule can be used in conjunction

  with `lt_now` and `gt_now` to control those ranges.



  ```protobuf

  // x must be within ±1s of the current time

  google.protobuf.Timestamp x = 1 [(validate.rules).timestamp.within.seconds = 1];



  // x must be within the range (now, now+1h)

  google.protobuf.Timestamp x = 1 [(validate.rules).timestamp = {

      gt_now: true,

      within: {seconds: 3600}

    }];

  ```



### Message-Global



- **disabled**: All validation rules for the fields on a message can be

  nullified, including any message fields that support validation themselves.



  ```protobuf

  message Person {

    option (validate.disabled) = true;



    // x will not be required to be greater than 123

    uint64 x = 1 [(validate.rules).uint64.gt = 123];



    // y's fields will not be validated

    Person y = 2;

  }

  ```



- **ignored**: Don't generate a validate method or any related validation code

  for this message.



  ```protobuf

  message Person {

    option (validate.ignored) = true;



    // x will not be required to be greater than 123

    uint64 x = 1 [(validate.rules).uint64.gt = 123];



    // y's fields will not be validated

    Person y = 2;

  }

  ```



### OneOfs



- **required**: require that one of the fields in a `oneof` must be set. By

  default, none or one of the unioned fields can be set. Enabling this rules

  disallows having all of them unset.



  ```protobuf

  oneof id {

    // either x, y, or z must be set.

    option (validate.required) = true;



    string x = 1;

    int32  y = 2;

    Person z = 3;

  }

  ```



## Development



PGV is written in Go on top of the [protoc-gen-star][pg*] framework and compiles

to a standalone binary.



### Dependencies



All PGV dependencies are currently checked into the project. To test

PGV, `protoc` must be installed, either from [source][protoc-source], the

provided [releases][protoc-releases], or a package manager. The official protoc

plugin for the target language(s) should be installed as well.



### Make Targets



- **`make build`**: generates the constraints proto and compiles PGV

  into `$GOPATH/bin`



- **`make lint`**: runs static-analysis rules against the PGV codebase,

  including `golint`, `go vet`, and `gofmt -s`



- **`make testcases`**: generates the proto files

  in [`/tests/harness/cases`](/tests/harness/cases). These are used by the test

  harness to verify the validation rules generated for each language.



- **`make harness`**: executes the test-cases against each language's test

  harness.



### Run all tests under Bazel



Ensure that your `PATH` is setup to include `protoc-gen-go` and `protoc`, then:



```

bazel test //tests/...

```



### Docker



PGV comes with a [Dockerfile](/Dockerfile) for consistent development tooling

and CI. The main entrypoint is `make` with `build` as the default target.



```sh

# build the image

docker build -t bufbuild/protoc-gen-validate .



# executes the default make target: build

docker run --rm \

  bufbuild/protoc-gen-validate



# executes the 'ci' make target

docker run --rm \

  bufbuild/protoc-gen-validate ci



# executes the 'build' & 'testcases' make targets

docker run --rm \

  bufbuild/protoc-gen-validate build testcases



# override the entrypoint and interact with the container directly

# this can be useful when wanting to run bazel commands without

# bazel installed locally.

docker run --rm \

 -it --entrypoint=/bin/bash \

 bufbuild/protoc-gen-validate

```



[buf]:             https://buf.build

[protoc-source]:   https://github.com/google/protobuf

[protoc-releases]: https://github.com/google/protobuf/releases

[pg*]:             https://github.com/bufbuild/protoc-gen-star

[re2]:             https://github.com/google/re2/wiki/Syntax

[wkts]:            https://developers.google.com/protocol-buffers/docs/reference/google.protobuf

[pv]:              https://github.com/bufbuild/protovalidate

[pv-announce]:     https://buf.build/blog/protoc-gen-validate-v1-and-v2/