FlatBuffers
An open source project by FPL.
Using the schema compiler

Usage:

flatc [ -c ] [ -j ] [ -b ] [ -t ] [ -o PATH ] [ -I PATH ] [ -S ] FILES...
      [ -- FILES...]

The files are read and parsed in order, and can contain either schemas or data (see below). Later files can make use of definitions in earlier files.

-- indicates that the following files are binary files in FlatBuffer format conforming to the schema(s) indicated before it. Incompatible binary files currently will give unpredictable results (!)

Depending on the flags passed, additional files may be generated for each file processed:

  • -c : Generate a C++ header for all definitions in this file (as filename_generated.h). Skipped for data.
  • -j : Generate Java classes. Skipped for data.
  • -n : Generate C# classes. Skipped for data.
  • -g : Generate Go classes. Skipped for data.
  • -b : If data is contained in this file, generate a filename.bin containing the binary flatbuffer.
  • -t : If data is contained in this file, generate a filename.json representing the data in the flatbuffer.
  • -o PATH : Output all generated files to PATH (either absolute, or relative to the current directory). If omitted, PATH will be the current directory. PATH should end in your systems path separator, e.g. / or \.
  • -I PATH : when encountering include statements, attempt to load the files from this path. Paths will be tried in the order given, and if all fail (or none are specified) it will try to load relative to the path of the schema file being parsed.
  • --strict-json : Require & generate strict JSON (field names are enclosed in quotes, no trailing commas in tables/vectors). By default, no quotes are required/generated, and trailing commas are allowed.
  • --defaults-json : Output fields whose value is equal to the default value when writing JSON text.
  • --no-prefix : Don't prefix enum values in generated C++ by their enum type.
  • --gen-includes : (deprecated), this is the default behavior. If the original behavior is required (no include statements) use --no-includes.
  • --no-includes : Don't generate include statements for included schemas the generated file depends on (C++).
  • --gen-mutable : Generate additional non-const accessors for mutating FlatBuffers in-place.
  • --gen-onefile : Generate single output file (useful for C#)
  • --raw-binary : Allow binaries without a file_indentifier to be read. This may crash flatc given a mismatched schema.
  • --proto: Expect input files to be .proto files (protocol buffers). Output the corresponding .fbs file. Currently supports: package, message, enum. Does not support, but will skip without error: import, option. Does not support, will generate error: service, extend, extensions, oneof, group, custom options, nested declarations.
  • --schema: Serialize schemas instead of JSON (use with -b). This will output a binary version of the specified schema that itself corresponds to the reflection/reflection.fbs schema. Loading this binary file is the basis for reflection functionality.