1FLATC(1) User Commands FLATC(1)
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6 flatc – FlatBuffers compiler
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9 flatc [OPTION]... FILE... [-- BINARY_FILE...]
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12 FILEs may be schemas (must end in .fbs), binary schemas (must end in
13 .bfbs), or JSON files (conforming to preceding schema). BINARY_FILEs
14 after the -- must be binary flatbuffer format files.
15 Output files are named using the base file name of the input, and writ‐
17 ten to the current directory or the path given by -o.
18 --binary, -b
20 Generate wire format binaries for any data definitions.
21 --json, -t
23 Generate text output for any data definitions.
24 --cpp, -c
26 Generate C++ headers for tables/structs.
27 --go, -g
29 Generate Go files for tables/structs.
30 --java, -j
32 Generate Java classes for tables/structs.
33 --dart, -d
35 Generate Dart classes for tables/structs.
36 --ts, -T
38 Generate TypeScript code for tables/structs.
39 --csharp, -n
41 Generate C# classes for tables/structs.
42 --python, -p
44 Generate Python files for tables/structs.
45 --lobster
47 Generate Lobster files for tables/structs.
48 --lua, -l
50 Generate Lua files for tables/structs.
51 --rust, -r
53 Generate Rust files for tables/structs.
54 --php Generate PHP files for tables/structs.
56 --kotlin
58 Generate Kotlin classes for tables/structs.
59 --jsonschema
61 Generate Json schema.
62 --swift
64 Generate Swift files for tables/structs.
65 --nim Generate Nim files for tables/structs.
67 -o PATH
69 Prefix PATH to all generated files.
70 -I PATH
72 Search for includes in the specified path.
73 -M Print make(1) rules for generated files.
75 --version
77 Print the version number of flatc and exit.
78 --strict-json
80 Strict JSON: field names must be / will be quoted, no trailing
81 commas in tables/vectors.
82 --allow-non-utf8
84 Pass non-UTF-8 input through parser and emit nonstandard \x es‐
85 capes in JSON. (Default is to raise parse error on non-UTF-8
86 input.)
87 --natural-utf8
89 Output strings with UTF-8 as human-readable strings. By de‐
90 fault, UTF-8 characters are printed as \uXXXX escapes.
91 --defaults-json
93 Output fields whose value is the default when writing JSON.
94 --unknown-json
96 Allow fields in JSON that are not defined in the schema. These
97 fields will be discared when generating binaries.
98 --no-prefix
100 Don’t prefix enum values with the enum type in C++.
101 --scoped-enums
103 Use C++11 style scoped and strongly typed enums. Also implies
104 --no-prefix.
105 --no-emit-min-max-enum-values
107 Disable generation of MIN and MAX enumerated values for scoped
108 enums and prefixed enums.
109 --gen-includes
111 (deprecated), this is the default behavior. If the original be‐
112 havior is required (no include statements) use --no-includes.
113 --no-includes
115 Don’t generate include statements for included schemas the gen‐
116 erated file depends on (C++ / Python).
117 --gen-mutable
119 Generate accessors that can mutate buffers in-place.
120 --gen-onefile
122 Generate single output file for C# and Go.
123 --gen-name-strings
125 Generate type name functions for C++ and Rust.
126 --gen-object-api
128 Generate an additional object-based API.
129 --gen-compare
131 Generate operator== for object-based API types.
132 --gen-nullable
134 Add Clang _Nullable for C++ pointer. or @Nullable for Java
135 --java-package-prefix
137 Add a prefix to the generated package name for Java.
138 --java-checkerframework
140 Add @Pure for Java.
141 --gen-generated
143 Add @Generated annotation for Java
144 --gen-jvmstatic
146 Add @JvmStatic annotation for Kotlin methods in companion object
147 for interop from Java to Kotlin.
148 --gen-all
150 Generate not just code for the current schema files, but for all
151 files it includes as well. If the language uses a single file
152 for output (by default the case for C++ and JS), all code will
153 end up in this one file.
154 --gen-json-emit
156 Generates encoding code which emits Flatbuffers into JSON.
157 --cpp-include
159 Adds an #include in generated file.
160 --cpp-ptr-type T
162 Set object API pointer type (default std::unique_ptr).
163 --cpp-str-type T
165 Set object API string type (default std::string). T::c_str(),
166 T::length(), and T::empty() must be supported. The custom type
167 also needs to be constructible from std::string (see the
168 --cpp-str-flex-ctor option to change this behavior).
169 --cpp-str-flex-ctor
171 Don’t construct custom string types by passing std::string from
172 Flatbuffers, but (char* + length).
173 --cpp-std CPP_STD
175 Generate a C++ code using features of selected C++ standard.
176 Supported CPP_STD values:
178 • c++0x – generate code compatible with old compilers;
180 • c++11 – use C++11 code generator (default);
182 • c++17 – use C++17 features in generated code (experimental).
184 --cpp-static-reflection
186 When using C++17, generate extra code to provide compile-time
187 (static) reflection of Flatbuffers types. Requires --cpp-std to
188 be “c++17” or higher.
189 --object-prefix
191 Customise class prefix for C++ object-based API.
192 --object-suffix
194 Customise class suffix for C++ object-based API. Default value
195 is “T”.
196 --go-namespace
198 Generate the overriding namespace in Golang.
199 --go-import
201 Generate the overriding import for flatbuffers in Golang (de‐
202 fault is “github.com/google/flatbuffers/go”).
203 --go-module-name
205 Prefix local import paths of generated go code with the module
206 name.
207 --raw-binary
209 Allow binaries without file_identifier to be read. This may
210 crash flatc given a mismatched schema.
211 --size-prefixed
213 Input binaries are size prefixed buffers.
214 --proto-namespace-suffix SUFFIX
216 Add this namespace to any flatbuffers generated from protobufs.
217 --oneof-union
219 Translate .proto oneofs to flatbuffer unions.
220 --keep-proto-id
222 Keep protobuf field ids in generated fbs file.
223 --proto-id-gap
225 Action that should be taken when a gap between protobuf ids
226 found.
227 Supported values:
229 • nop – do not care about gap
231 • warn – A warning message will be shown about the gap in proto‐
233 buf ids (default)
234 • error – An error message will be shown and the fbs generation
236 will be interrupted.
237 --grpc Generate GRPC interfaces for the specified languages.
239 --schema
241 Serialize schemas instead of JSON (use with -b).
242 --bfbs-comments
244 Add doc comments to the binary schema files.
245 --bfbs-builtins
247 Add builtin attributes to the binary schema files.
248 --bfbs-gen-embed
250 Generate code to embed the bfbs schema to the source.
251 --conform FILE
253 Specify a schema the following schemas should be an evolution
254 of. Gives errors if not.
255 --conform-includes
257 Include path for the schema given with --conform PATH.
258 --filename-suffix
260 The suffix appended to the generated file names. Default is
261 ‘_generated’.
262 --filename-ext
264 The extension appended to the generated file names. Default is
265 language-specific (e.g., ‘.h’ for C++)
266 --include-prefix PATH
268 Prefix this path to any generated include statements.
269 --keep-prefix
271 Keep original prefix of schema include statement.
272 --reflect-types
274 Add minimal type reflection to code generation.
275 --reflect-names
277 Add minimal type/name reflection.
278 --rust-serialize
280 Implement serde::Serialize on generated Rust types.
281 --rust-module-root-file
283 Generate rust code in individual files with a module root file.
284 --root-type T
286 Select or override the default root_type.
287 --require-explicit-ids
289 When parsing schemas, require explicit ids (id: x).
290 --force-defaults
292 Emit default values in binary output from JSON.
293 --force-empty
295 When serializing from object API representation, force strings
296 and vectors to empty rather than null.
297 --force-empty-vectors
299 When serializing from object API representation, force vectors
300 to empty rather than null.
301 --flexbuffers
303 Used with “binary” and “json” options, it generates data using
304 schema-less FlexBuffers.
305 --no-warnings
307 Inhibit all warning messages.
308 --warnings-as-errors
310 Treat all warnings as errors.
311 --cs-global-alias
313 Prepend “global::” to all user generated csharp classes and
314 structs.
315 --cs-gen-json-serializer
317 Allows (de)serialization of JSON text in the Object API. (re‐
318 quires --gen-object-api).
319 --json-nested-bytes
321 Allow a nested_flatbuffer field to be parsed as a vector of
322 bytes in JSON, which is unsafe unless checked by a verifier af‐
323 terwards.
324 --ts-flat-files
326 Generate a single typescript file per .fbs file. Implies
327 --ts-entry-points.
328 --ts-entry-points
330 Generate entry point typescript per namespace. Implies
331 --gen-all.
332 --annotate-sparse-vectors SCHEMA
334 Don’t annotate every vector element.
335 --annotate SCHEMA
337 Annotate the provided BINARY_FILE with the specified SCHEMA
338 file.
339 --no-leak-private-annotation
341 Prevents multiple type of annotations within a Fbs SCHEMA file.
342 Currently this is required to generate private types in Rust.
343 --python-no-type-prefix-suffix
345 Skip emission of Python functions that are prefixed with type‐
346 names
347 --python-typing
349 Generate Python type annotations
350 --file-names-only
352 Print out generated file names without writing to the files
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355 flatc -c -b schema1.fbs schema2.fbs data.json
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358 Official documentation ⟨https://google.github.io/flatbuffers⟩
359 October 2022 FLATC(1)