json.encode(table [,compatible])

Convert a Lua table into a JSON encoded string. The special value json.NULL can be used to store a null value in a Lua table since it is not possible to store a Lua null value in a table.

JSON supports an array with integer indexes or an object that has string indexes whereas Lua allows a table to use integer and string values for keys in the same table. To allow any Lua table to be serialized to a string, nzLua by default uses an encoding format that may result in a serialized table that is not compatible with standard JSON. For example, the table below cannot be encoded in the standard JSON format since it has both integer indexes and a string index.

t = {111,222,333,foo="abc"}

Using json.encode(t) on this table will yield the string '{1:111,2:222,3:333,"foo":"abc"}' which is not a legal encoding for JSON, whereas json.encode(t,true) will yield the string '{"1":111,"2":222,"3":333,"foo":"abc"}'. In the compatible format, all of the integer keys of the table are converted to string keys.

The json.encode function makes no attempt to detect recursive tables, therefore the code shown below will result in a stack overflow error.

t = {1,2,3}
t[4] = t
str = json.encode(t)

Example

t = {a=123,b=987,c=333,d=json.NULL}
str = json.encode(t)