local rapidjson = require('rapidjson')
print( rapidjson.encode({}) ) -- '{}'
print( rapidjson.encode(rapidjson.object()) ) --> '{}'
print( rapidjson.encode(rapidjson.array()) ) --> '[]'
print( rapidjson.encode(setmetatable({}, {__jsontype='object'})) ) --> '{}'
print( rapidjson.encode(setmetatable({}, {__jsontype='array'})) ) --> '[]'
print( rapidjson.encode(true) ) --> 'true'
print( rapidjson.encode(rapidjson.null) ) --> 'null'
print( rapidjson.encode(123) ) --> '123.0' or '123' in Lua 5.3.
print( rapidjson.encode({true, false}) ) --> '[true, false]'
print( rapidjson.encode({a=true, b=false}) ) --> '{"a":true,"b":false]'
Debug Output
{}
[true,false]
{"a":true,"b":false}
Example 2: Sort object keys
rapidjson = require("rapidjson")
function TablePretty(tbl,sort)
return rapidjson.encode(tbl,{ pretty=true, sort_keys=sort })
end
test = {
["Top Level Item"]={
Value=math.pi,
Str="String",
Options={1,2,3,4} -- an "array"
}
}
print(TablePretty(test,true))
Debug Output
{
"Top Level Item": {
"Options": [
"Str": "String",
"Value": 3.141592653589793
value = rapidjson.decode(jsonstring)
Arguments
jsonstring : A JSON value string to be decoded.
Returns
Return table if JSON is an object or array.
Return true, false, number and rapidjson.null respectively if JSON is a simple value.
Return nil plus an error message as a second result when passed string is not a valid JSON.
Errors
When passed value is not (convertable to) string.
rapidjson.load()Load JSON file into Lua table.
Syntax
value = rapidjson.load(filename)
Arguments
filename : The JSON file to be loaded.
Returns
Return table if file contains an object or array.
Return true, false, number and rapidjson.null respectively if file contains a simple value.
Return nil plus an error message as a second result when passed file is not valid JSON file.
Errors
When passed filename is not (convertible to) string.
rapidjson.Document()Creates a rapidjson Document object. Optionally create from a Lua table or string of JSON document.
Syntax
doc = rapidjson.Document(t|s)
Arguments
t : Optional table to be create a rapidjson Document from.
s : Optional a string contains a JSON document, then when document created the string is parsed into the document.
document:parse()Parse JSON document contained in string s.
Syntax
local ok, message = document:parse(s)
Arguments
s : A string contains a JSON document.
Returns
Returns true on success.
Returns false and additional error message when failed.
Example
local rapidjson = require('rapidjson')
local doc = rapidjson.Document()
local ok, message = doc:parse('{"a":["appke", "air"]}')
if not ok then
print(message)
end
Local value = document:get(pointer[, default])
Arguments
pointer : A string contains JSON pointer.
default : The default value to return if the document does not contains value specified by the pointer.
Returns
If the document has elements specified by pointer, the element value is returned as a Lua value. Otherwise default value is returned.
Returns nil if default is not specified.
document:set()Set document member by JSON Pointer with specified value.
Syntax
document:set(pointer, value)
Arguments
pointer : A string contains JSON pointer.
value : The value to set as new value for document element specified by pointer.
Example
local doc = rapidjson.Document()
doc:set('/a', {'apple', 'air'})
success, err = rapidjson.dump(value, filename [, option])
Arguments
value : Same as in rapidjson.encode().
filename : The file path string where to save the rapidjson string.
option : Same as in options in rapidjson.encode().
Example
local rapidjson = require('rapidjson')
rapidjson.dump({rapidjson.null}, 'media/test.json')
rapidjson.dump({rapidjson.null}, 'media/test-pretty.json', {pretty=true})
Note: For security and stability reasons, the media/ folder and design/ folder and their subfolders are the only locations within the file system accessible by the Lua libraries.
rapidjson.nullThe placeholder for null values in rapidjson.
Example
local rapidjson = require('rapidjson')
rapidjson.decode('[null]') --> {rapidjson.null}
rapidjson.encode({rapidjson.null}) --> '[null]'
rapidjson.object()Create a new empty table that has the metatable field __jsontype set as 'object' so that the encode and dump function will encode it as a JSON object.
When passed a valid table:
Passed table does not have metatable - just set above metatable for the table.
Passed table already has metatable - set the metatable field __jsontype to 'object'.
Synopsis
obj = rapidjson.object([t])
Arguments
t : Optional table to set the metatable with meta field __jsontype set as 'object'.
Returns
Origin passed in table when passed with a table. Or new created table.
rapidjson.array()Same as rapidjson.object(), except the metatable field __jsontype is set as 'array'. The encode and dump function will encode it as JSON array.
See rapidjson.object() for usage.
rapidjson.SchemaDocument()Creates a SchemaDocument from Document or a Lua table or a string contains a JSON schema.
Syntax
local sd = rapidjson.SchemaDocument(doc|t|s)
Arguments
doc : The the JSON schema stored in rapidjson.Document object.
t : The Lua table representation of a JSON schema.
s : The string contains a JSON schema.
Returns
Returns the new SchemaDocument object.
Example
local d = rapidjson.Document('{"type": ["string", "number"]}')
local sd = rapidjson.SchemaDocument(d)
local validator = apidjson.SchemaValidator(sd)
Arguments
sd : The SchemaDocument to create the validator. SchemaDocument can be shared by schema validators.
Returns
Returns the new created validator object.
Example
local sd = rapidjson.SchemaDocument('{"type": ["string", "number"]}')
local validator = rapidjson.SchemaValidator(sd)
local d = rapidjson.Document('.....')
local ok, message = validator:validate(d)
local ok, message = validator:validate(d)
Arguments
d : The document to be validated against the schema stored inside the validator.
Returns
Returns true if the document is valid.
Returns false and an extra error message if invalid.
Portions of this topic are reprinted under permission of the lua-rapidjson license.
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