1Using the schema compiler {#flatbuffers_guide_using_schema_compiler} 2========================= 3 4Usage: 5 6 flatc [ GENERATOR OPTIONS ] [ -o PATH ] [ -I PATH ] FILES... 7 [ -- FILES...] 8 9The files are read and parsed in order, and can contain either schemas 10or data (see below). Data files are processed according to the definitions of 11the most recent schema specified. 12 13`--` indicates that the following files are binary files in 14FlatBuffer format conforming to the schema indicated before it. 15 16Depending on the flags passed, additional files may 17be generated for each file processed: 18 19For any schema input files, one or more generators can be specified: 20 21- `--cpp`, `-c` : Generate a C++ header for all definitions in this file (as 22 `filename_generated.h`). 23 24- `--java`, `-j` : Generate Java code. 25 26- `--kotlin`, `-k` : Generate Kotlin code. 27 28- `--csharp`, `-n` : Generate C# code. 29 30- `--go`, `-g` : Generate Go code. 31 32- `--python`, `-p`: Generate Python code. 33 34- `--js`, `-s`: Generate JavaScript code. 35 36- `--ts`: Generate TypeScript code. 37 38- `--php`: Generate PHP code. 39 40- `--grpc`: Generate RPC stub code for GRPC. 41 42- `--dart`: Generate Dart code. 43 44- `--lua`: Generate Lua code. 45 46- `--lobster`: Generate Lobster code. 47 48- `--rust`, `-r` : Generate Rust code. 49 50- `--swift`: Generate Swift code. 51 52For any data input files: 53 54- `--binary`, `-b` : If data is contained in this file, generate a 55 `filename.bin` containing the binary flatbuffer (or a different extension 56 if one is specified in the schema). 57 58- `--json`, `-t` : If data is contained in this file, generate a 59 `filename.json` representing the data in the flatbuffer. 60 61Additional options: 62 63- `-o PATH` : Output all generated files to PATH (either absolute, or 64 relative to the current directory). If omitted, PATH will be the 65 current directory. PATH should end in your systems path separator, 66 e.g. `/` or `\`. 67 68- `-I PATH` : when encountering `include` statements, attempt to load the 69 files from this path. Paths will be tried in the order given, and if all 70 fail (or none are specified) it will try to load relative to the path of 71 the schema file being parsed. 72 73- `-M` : Print make rules for generated files. 74 75- `--strict-json` : Require & generate strict JSON (field names are enclosed 76 in quotes, no trailing commas in tables/vectors). By default, no quotes are 77 required/generated, and trailing commas are allowed. 78 79- `--allow-non-utf8` : Pass non-UTF-8 input through parser and emit nonstandard 80 \x escapes in JSON. (Default is to raise parse error on non-UTF-8 input.) 81 82- `--natural-utf8` : Output strings with UTF-8 as human-readable strings. 83 By default, UTF-8 characters are printed as \uXXXX escapes." 84 85- `--defaults-json` : Output fields whose value is equal to the default value 86 when writing JSON text. 87 88- `--no-prefix` : Don't prefix enum values in generated C++ by their enum 89 type. 90 91- `--scoped-enums` : Use C++11 style scoped and strongly typed enums in 92 generated C++. This also implies `--no-prefix`. 93 94- `--gen-includes` : (deprecated), this is the default behavior. 95 If the original behavior is required (no include 96 statements) use `--no-includes.` 97 98- `--no-includes` : Don't generate include statements for included schemas the 99 generated file depends on (C++ / Python). 100 101- `--gen-mutable` : Generate additional non-const accessors for mutating 102 FlatBuffers in-place. 103 104- `--gen-onefile` : Generate single output file for C# and Go. 105 106- `--gen-name-strings` : Generate type name functions for C++. 107 108- `--gen-object-api` : Generate an additional object-based API. This API is 109 more convenient for object construction and mutation than the base API, 110 at the cost of efficiency (object allocation). Recommended only to be used 111 if other options are insufficient. 112 113- `--gen-compare` : Generate operator== for object-based API types. 114 115- `--gen-nullable` : Add Clang _Nullable for C++ pointer. or @Nullable for Java. 116 117- `--gen-generated` : Add @Generated annotation for Java. 118 119- `--gen-jvmstatic` : Add @JvmStatic annotation for Kotlin methods 120 in companion object for interop from Java to Kotlin. 121 122- `--gen-all` : Generate not just code for the current schema files, but 123 for all files it includes as well. If the language uses a single file for 124 output (by default the case for C++ and JS), all code will end up in 125 this one file. 126 127- `--cpp-include` : Adds an #include in generated file 128 129- `--cpp-ptr-type T` : Set object API pointer type (default std::unique_ptr) 130 131- `--cpp-str-type T` : Set object API string type (default std::string) 132 T::c_str(), T::length() and T::empty() must be supported. 133 The custom type also needs to be constructible from std::string (see the 134 --cpp-str-flex-ctor option to change this behavior). 135 136- `--cpp-str-flex-ctor` : Don't construct custom string types by passing 137 std::string from Flatbuffers, but (char* + length). This allows efficient 138 construction of custom string types, including zero-copy construction. 139 140- `--no-cpp-direct-copy` : Don't generate direct copy methods for C++ 141 object-based API. 142 143- `--cpp-std CPP_STD` : Generate a C++ code using features of selected C++ standard. 144 Supported `CPP_STD` values: 145 * `c++0x` - generate code compatible with old compilers (VS2010), 146 * `c++11` - use C++11 code generator (default), 147 * `c++17` - use C++17 features in generated code (experimental). 148 149- `--object-prefix` : Customise class prefix for C++ object-based API. 150 151- `--object-suffix` : Customise class suffix for C++ object-based API. 152 153- `--go-namespace` : Generate the overrided namespace in Golang. 154 155- `--go-import` : Generate the overrided import for flatbuffers in Golang. 156 (default is "github.com/google/flatbuffers/go"). 157 158- `--raw-binary` : Allow binaries without a file_indentifier to be read. 159 This may crash flatc given a mismatched schema. 160 161- `--size-prefixed` : Input binaries are size prefixed buffers. 162 163- `--proto`: Expect input files to be .proto files (protocol buffers). 164 Output the corresponding .fbs file. 165 Currently supports: `package`, `message`, `enum`, nested declarations, 166 `import` (use `-I` for paths), `extend`, `oneof`, `group`. 167 Does not support, but will skip without error: `option`, `service`, 168 `extensions`, and most everything else. 169 170- `--oneof-union` : Translate .proto oneofs to flatbuffer unions. 171 172- `--grpc` : Generate GRPC interfaces for the specified languages. 173 174- `--schema`: Serialize schemas instead of JSON (use with -b). This will 175 output a binary version of the specified schema that itself corresponds 176 to the reflection/reflection.fbs schema. Loading this binary file is the 177 basis for reflection functionality. 178 179- `--bfbs-comments`: Add doc comments to the binary schema files. 180 181- `--conform FILE` : Specify a schema the following schemas should be 182 an evolution of. Gives errors if not. Useful to check if schema 183 modifications don't break schema evolution rules. 184 185- `--conform-includes PATH` : Include path for the schema given with 186 `--conform PATH`. 187 188- `--filename-suffix SUFFIX` : The suffix appended to the generated 189 file names. Default is '_generated'. 190 191- `--filename-ext EXTENSION` : The extension appended to the generated 192 file names. Default is language-specific (e.g. "h" for C++). This 193 should not be used when multiple languages are specified. 194 195- `--include-prefix PATH` : Prefix this path to any generated include 196 statements. 197 198- `--keep-prefix` : Keep original prefix of schema include statement. 199 200- `--reflect-types` : Add minimal type reflection to code generation. 201 202- `--reflect-names` : Add minimal type/name reflection. 203 204- `--root-type T` : Select or override the default root_type. 205 206- `--require-explicit-ids` : When parsing schemas, require explicit ids (id: x). 207 208- `--force-defaults` : Emit default values in binary output from JSON. 209 210- `--force-empty` : When serializing from object API representation, force 211 strings and vectors to empty rather than null. 212 213- `--force-empty-vectors` : When serializing from object API representation, force 214 vectors to empty rather than null. 215 216- `--flexbuffers` : Used with "binary" and "json" options, it generates 217 data using schema-less FlexBuffers. 218 219- `--no-warnings` : Inhibit all warning messages. 220 221NOTE: short-form options for generators are deprecated, use the long form 222whenever possible. 223