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Use in Lua

Before you get started

Before diving into the FlatBuffers usage in Lua, it should be noted that the [Tutorial](@ref flatbuffers_guide_tutorial) page has a complete guide to general FlatBuffers usage in all of the supported languages (including Lua). This page is designed to cover the nuances of FlatBuffers usage, specific to Lua.

You should also have read the [Building](@ref flatbuffers_guide_building) documentation to build flatc and should be familiar with [Using the schema compiler](@ref flatbuffers_guide_using_schema_compiler) and [Writing a schema](@ref flatbuffers_guide_writing_schema).

FlatBuffers Lua library code location

The code for the FlatBuffers Lua library can be found at flatbuffers/lua. You can browse the library code on the FlatBuffers GitHub page.

Testing the FlatBuffers Lua library

The code to test the Lua library can be found at flatbuffers/tests. The test code itself is located in [luatest.lua](https://github.com/google/ flatbuffers/blob/master/tests/luatest.lua).

To run the tests, use the [LuaTest.sh](https://github.com/google/flatbuffers/ blob/master/tests/LuaTest.sh) shell script.

Note: This script requires Lua 5.3 to be installed.

Using the FlatBuffers Lua library

Note: See [Tutorial](@ref flatbuffers_guide_tutorial) for a more in-depth example of how to use FlatBuffers in Lua.

There is support for both reading and writing FlatBuffers in Lua.

To use FlatBuffers in your own code, first generate Lua classes from your schema with the --lua option to flatc. Then you can include both FlatBuffers and the generated code to read or write a FlatBuffer.

For example, here is how you would read a FlatBuffer binary file in Lua: First, require the module and the generated code. Then read a FlatBuffer binary file into a string, which you pass to the GetRootAsMonster function:

    -- require the library
    local flatbuffers = require("flatbuffers")
    
    -- require the generated code
    local monster = require("MyGame.Sample.Monster")

    -- read the flatbuffer from a file into a string
    local f = io.open('monster.dat', 'rb')
    local buf = f:read('*a')
    f:close()

    -- parse the flatbuffer to get an instance to the root monster
    local monster1 = monster.GetRootAsMonster(buf, 0)

Now you can access values like this:

    -- use the : notation to access member data
    local hp = monster1:Hp()
    local pos = monster1:Pos()

Text Parsing

There currently is no support for parsing text (Schema's and JSON) directly from Lua, though you could use the C++ parser through SWIG or ctypes. Please see the C++ documentation for more on text parsing.

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