Result

#include <vgi_rpc/result.h>

Constructs RPC response batches returned from unary method handlers.

Static Factories

value (from batch)

static Result value(std::shared_ptr<arrow::RecordBatch> batch);

Create a result wrapping a pre-built record batch.

value (from schema + arrays)

static Result value(
    std::shared_ptr<arrow::Schema> schema,
    std::vector<std::shared_ptr<arrow::Array>> arrays);

Create a result from a schema and a vector of arrays. Builds a one-row batch.

from_annotated_batch

static Result from_annotated_batch(AnnotatedBatch ab);

Create a result from an AnnotatedBatch (batch + custom metadata).

void_result

static Result void_result();

Create a void result (zero-row batch on an empty schema). Use for add_void() handlers that need to return explicitly.

error

static Result error(
    std::shared_ptr<arrow::Schema> schema,
    const std::string& exception_type,
    const std::string& message,
    const std::string& server_id = "",
    const std::string& request_id = "");

Create an error result with EXCEPTION metadata. Typically you don't need this — throwing an exception from a handler is the preferred way to signal errors.

Accessors

annotated_batch

const AnnotatedBatch& annotated_batch() const noexcept;

schema

const std::shared_ptr<arrow::Schema>& schema() const;

make_error_metadata

std::shared_ptr<arrow::KeyValueMetadata> make_error_metadata(
    const std::string& exception_type,
    const std::string& message,
    const std::string& server_id = "",
    const std::string& request_id = "");

Build the standard error metadata used for both unary error results and mid-stream error batches.

Example

// Return a value
auto handler = [](const vgi_rpc::Request& req, vgi_rpc::CallContext& ctx) {
    arrow::DoubleBuilder builder;
    VGI_RPC_THROW_NOT_OK(builder.Append(42.0));
    auto array = vgi_rpc::unwrap(builder.Finish());

    return vgi_rpc::Result::value(
        arrow::schema({arrow::field("answer", arrow::float64())}),
        {array});
};

// Signal error (prefer throwing instead)
// throw std::runtime_error("something went wrong");