Package org.mockserver.grpc

Class GrpcExampleSynthesizer

java.lang.Object
org.mockserver.grpc.GrpcExampleSynthesizer
public class GrpcExampleSynthesizer extends Object
Synthesizes schema-valid example protobuf messages from a loaded protobuf Descriptors.Descriptor. This is the gRPC analogue of the GraphQL GraphQLResponseSynthesizer and the OpenAPI ExampleBuilder: given a message type from a descriptor loaded via PUT /mockserver/grpc/descriptors, it walks the message's fields and emits a deterministic, type-correct placeholder value for every field — no hand-authored response body required.

The synthesizer builds a real DynamicMessage rather than hand-rolling JSON, so the result is guaranteed to be a valid instance of the message type and round-trips cleanly through GrpcJsonMessageConverter (well-known types such as google.protobuf.Timestamp are rendered by the standard protobuf-JSON printer when the type registry knows them).

Synthesis rules:

  • scalars produce deterministic placeholders by Java/proto type (string "string", numbers 0/0.0, bool true, bytes empty)
  • enums produce their first declared value (index 0)
  • nested messages recurse into a synthesized sub-message
  • repeated fields produce a single synthesized element
  • map fields produce a single synthesized entry
  • well-known message types (Timestamp, Duration, the scalar wrappers, Struct/Value/Empty) get sensible canonical values
  • recursion is bounded; a message type already on the current path is left at its proto default to avoid infinite recursion on self-referential schemas

Instances are stateless and thread-safe.

  • Constructor Details

    • GrpcExampleSynthesizer

      public GrpcExampleSynthesizer()

  • Method Details

    • synthesizeJson

      public String synthesizeJson(com.google.protobuf.Descriptors.Descriptor messageDescriptor, GrpcJsonMessageConverter converter)
      Synthesize a schema-valid example message for the supplied message descriptor and render it as protobuf-JSON via the supplied converter.
      Parameters:
      messageDescriptor - the message type to synthesize (e.g. a method's output type)
      converter - the converter used to render the message as protobuf-JSON
      Returns:
      a protobuf-JSON string that is a valid instance of messageDescriptor
      Throws:
      GrpcException - if synthesis or rendering fails

    • synthesizeMessage

      public com.google.protobuf.DynamicMessage synthesizeMessage(com.google.protobuf.Descriptors.Descriptor messageDescriptor)
      Synthesize a schema-valid example DynamicMessage for the supplied message descriptor.