Copyright (C) 2016, ICSON company, ZhengFeng Rao, NASaCJ. All rights reserved.
| Platfrom | Linux |
|---|---|
| Status |
JSON is a kind of Object notation. When programmers deal with the json strings by C++ json APIs (eg, RapidJSON, jsoncpp) they have to write codes for parsing each different Class, which there may be a lot of similar repeated API calling codes. So json2cpp can help programmer to auto-generate the C++ codes for transferring form JSON to C++ and conversely. json2cpp is a script tool written in python language. It uses pyparsing to parse a Modeling file to C++ files and RapidJSON, jsoncpp for C++ to parse the JSON.
- json2cpp depends on Python and pyparsing, so make sure that Python has been installed on your System
- For installing pyparsing, use "easy_install" to install it through command line:
user@localhost $ sudo easy_install pyparsingThie simple instruction shows a common running command of json2cpp
git clone https://github.com/nasacj/json2cpp
cd json2cpp
./json2cpp.py rapidjson sample.jsf test
cd test/test
make
./testSee the LICENSE file for details. In summary, json2cpp is licensed under the MIT license, or public domain if desired and recognized in your jurisdiction.
json2cpp uses RapidJSON & jsoncpp, which 2 are both under MIT license.
Before use json2cpp, a definition file is required:
As sample.jsf file shows, user can define the class structure as C++ sytle. The classes are according to the JSON objects:
{
"sourceId": 1,
"orgId": 10,
"ivcType": 100,
"reqNo": "asd",
"payerNo": "10032-11",
"businessIds": [
"saddd",
"xxxx"
],
"invoiceTicket": {
"invoiceType": "Normal",
"invoiceCode": "200001",
"invoiceAddress": {
"provinceNo": 10001,
"provinceStr": "New York",
},
"optionalAddress": [
{
"provinceNo": 10002,
"provinceStr": "Shanghi",
},
{
"provinceNo": 10003,
"provinceStr": "Beijing",
}
]
}
}{
"code": "200",
"msg": "This is msg",
"reqNo": "100200012",
"businessIds": [
"111asd",
"2cde2"
],
"invoiceTicket": {
"invoiceType": "Normal",
"invoiceCode": "200001",
"invoiceAddress": {
"provinceNo": 10001,
"provinceStr": "Shanghai",
},
"optionalAddress": [
{
"provinceNo": 10002,
"provinceStr": "Beijing",
},
{
"provinceNo": 10003,
"provinceStr": "Hong Kong",
}
]
}
}//namespace Definition
namespace jsf;
//Class Definition
@description="Address Structure" //@descpription is optional
class Address
{
@jsonname="provinceNo", description="Province ID" //@descpription is optional
int provinceNo;
@jsonname="provinceStr", description="Province"
string province;
};
//@descpription is optional
class InvoiceTicket
{
@jsonname="invoiceType" //@descpription is optional
string invoiceType;
@jsonname="invoiceCode", description="Invoice Code"
string invoiceCode;
@jsonname="invoiceAddress", description="Inoice Address"
Address address;
@jsonname="optionalAddress"
vector<Address> optionalAddress; //Only use vector for list handling
};
//The Interface which handles the serialization of JSON
@description="Add Invoice Interface"
Interface AddInvoice {
Request {
@jsonname="sourceId", description="Source"
int source;
@jsonname="orgId", description="Organization"
int organizationId;
@jsonname="ivcType",description="Type"
int invoiceType;
@jsonname="reqNo", description="Rquest Number"
string requestNo;
@jsonname="payerNo", description="Payer No"
string payNo;
@jsonname="receiverNo", description="ReceiverNo", optional="true" //Optional member
string receiverNo ;
@jsonname="businessIds", description="Business ID List"
vector<string> bussinessIds;
@jsonname="invoiceTicket", description="Invoice Ticket"
InvoiceTicket invoiceTicket;
};
Response {
@jsonname="code", description="Return Code"
string code;
@jsonname="msg", description="Message"
string message;
@jsonname="reqNo", description="Require Number"
string requestNo;
@jsonname="businessIds", description="BusinessID", optional="true"
vector<string> bussinessIds ;
@jsonname="invoiceTicket", description="Invoice Ticket"
InvoiceTicket invoiceTicket;
};
};./json2cpp.py rapidjson sample.jsf dir_testCommand json2cpp takes 3 arguements: {rapidjson/jsoncpp} {Class definitation File} {Directory} Outputs in dir_test path is organized by the namespace defined in sample.jsf:
dir_test
├── jsf
├── AddInvoice.h
├── Address.h
├── InvoiceTicket.h
├── json2cpp.h
├── base.h
├── macro.h
└── rapidjson
├── ......
......
base.h: defines the basic object access:
- Field<>: Every json object in interface class are all Field type. It has Get/SetVaule()
- IRequest: ToJson() serialize C++ Object to JSON string
- IResponse: FromJson() unserialize JSON string to C++ Object macro.h: defines some marcos for internel use. json2cpp.h: include all header files, provide for other to use.
json2cpp will generate a hpp file each user defined class and interface. AddInvoice.h: interface AddInvoice implemention. AddWare.h: interface AddWare implemention. Address.h: user define class Address implemention. InvoiceTicket.h: user define class InvoiceTicket implemetion.
all you have to do is include header file "json2cpp.h", and use the classes generated.
#include "json2cpp.h"
/**** Request Sample ****/
AddInvoiceRequest request;
Address address;
Address address1;
InvoiceTicket invoTic;
address.m_provinceNo.SetValue(10001);
... //set address and address1 members
invoTic.m_invoiceType.SetValue("Normal");
... //set invoTic members
vector<Address> v_addr;
v_addr.push_back(address1);
invoTic.m_optionalAddress.SetValue(v_addr);
//Set the Request values:
request.m_source.SetValue(1);
request.m_organizationId.SetValue(10);
request.m_invoiceType.SetValue(100);
request.m_requestNo.SetValue("asd");
request.m_payNo.SetValue("10032-11");
std::vector<std::string> bid;
bid.push_back("saddd");
bid.push_back("xxxx");
request.m_bussinessIds.SetValue(bid);
request.m_invoiceTicket.SetValue(invoTic);
std::string str;
std::string error;
uint32_t ret = request.ToJson(str, error);
if (json2cpp::ERR_OK != ret)
{
std::cout<<"error:"<<ret<<", "<<error<<std::endl;
return;
}
/**** Response Sample ****/
ifstream fin("json.txt");
getline(fin,str);
uint32_t status = 200;
AddInvoiceResponse response;
uint32_t ret = response.FromJson(str, status);
if(ret != json2cpp::ERR_OK)
{
std::cout<<"error:"<<ret<<", "<<response.m_JSFMessage.GetValue()<<std::endl;
return;
}//namespace, allow 0 or more
(namespace {name_space};)
//user define class, allow 0 or more
(
(@description="{description_str}")
class {class_name}{
@jsonname={json_filed_name}(,description="{description_str}", optional=["true","false"], default="{default_value_str}")
[field_type] {field_name};
};
)
//interface, allow 1 or more
(@description="{description_str}")
Interface {interface_name}{
//request, must have only 1 for every interface
Request{
@jsonname={json_filed_name}(,description="{description_str}", optional=["true","false"], default="{default_value_str}")
[field_type] {field_name} (optional);
};
//response, must have only 1 for every interface
Response{
@jsonname={json_filed_name}(,description="{description_str}", optional=["true","false"], default="{default_value_str}")
[field_type] {field_name} (optional);
};
};
- () means the grammar token is optional, it can be defined 0 or 1
- {} means variable name
- @ means comments
- [] means specified value of the set
-
{name_space} means C++ style namespace
-
{class_name}, {interface_name}, {field_name}, {json_filed_name} means self-defined struct/class, Interface, Field Name, JSON Field name. They can be any valid string
-
User can define 1 or more class, the definitation sequence should follow the C++ style
-
User can define 1 or more Interface，each Interface MUST have a pair of request/response objects
-
@ means comments，now it supports jsonname, description, optional, default key-words:
Key-Word Description jsonname JSON Field Name [It MUST be specified] description It will be generated into C++ code for comments [Optional] optional Specifies the JSON field is optional，value should be "true" or "false"，default is"false" [Optional] default Specifies the default value of C++ member feild [Optional] -
[field_type] Filed Type. Now supporting short, int, bool, uint32_t, uint64_t, int64_t, double, self-define class T and vector<T>.
-
Supports C++ sytle comments like
//commentsand/*comments*/, the commots will be ignored when being parsing.
json2cpp supports anonymous array Request/Response, like the following JSON string:
[
{
"provinceNo": 10002,
"provinceStr": "Beijing",
},
{
"provinceNo": 10003,
"provinceStr": "Hong Kong",
}
]This JSON string only contains an anonymous array of "Address", so the grammar is defined as following style:
@description="AddWare"
Interface AddWare{
Request {
@jsonname="", description="Request Addresses"
vector<Address> addresses;
};
Response {
.......
};When Request/Respons is an anonymous array JSON string, the @jsonname MUST be defined as "" (null), and the Field should ONLY contains ONE AND ONLY ONE vector type class or normal type (e.g. vector<Address>, vector<int>).
User can use defined Class to be inherited to Request/Response, which means user can reuse the definitation of a Class, put the fields of that class into Request/Response. For instance, Address has 2 fields: {int, string}. If the Request and Response are both required as a single Address Object (NOT an Object contains an Address). So the definitation file can be written as following:
// Tedious definitation:
@description="AddWare"
Interface AddWare{
Request {
@jsonname="provinceNo", description="Province ID" //@descpription is optional
int provinceNo;
@jsonname="provinceStr", description="Province"
string province;
};
Response {
@jsonname="provinceNo", description="Province ID" //@descpription is optional
int provinceNo;
@jsonname="provinceStr", description="Province"
string province;
};
};
// Can be simplified as following --->
@description="AddWare"
Interface AddWare{
Request(Address) {};
Response(Address){};
};- If (class_type) follows Request/Response, the Fields in Request/Response is optional (ZeroOrMore).
- If Inheritance is not used, Fields in Request/Response is OneOrMore