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std:json

The std:json module provides functions to encode Lua tables into JSON strings and decode JSON strings into Lua tables. It is useful for data interchange, API communication, and configuration parsing.

Functions​

json.encode(tbl: table): string​

Encodes a Lua table into a JSON string. Nested tables and arrays are supported.

  • Parameters:

    • tbl (table): the Lua table to encode.

  • Returns:

    • (string): the JSON representation of the table.

Example:

local json = require("std:json")

local tbl = { name = "Alice", age = 30, active = true }
local str = json.encode(tbl)
print(str)
-- {"name":"Alice","age":30,"active":true}

json.decode(str: string): table​

Decodes a JSON string into a Lua table. Nested objects and arrays are converted recursively.

  • Parameters:

    • str (string): the JSON string to decode.

  • Returns:

    • (table): the Lua table representation of the JSON string.

Example:

local json = require("std:json")

local str = '{"users":[{"name":"Alice"},{"name":"Bob"}],"active":true}'
local tbl = json.decode(str)

print(tbl.active)          -- true
print(tbl.users[1].name)   -- Alice
print(tbl.users[2].name)   -- Bob

Notes​

  • Arrays in JSON are converted to Lua tables with 1-based integer keys.
  • Nested objects and arrays are recursively converted.
  • Invalid JSON strings will raise an error.

Example of error handling:

local json = require("std:json")

local ok, err = pcall(function()
    local tbl = json.decode('{"invalid_json": }')
end)

print(ok, err)
-- false    failed to decode JSON string: ...