Reading JSON from a file using C++ REST SDK (Casablanca) - c++

Question

I have the following code which should read the contents of a text file and parse it as JSON
try {
string_t importFile = argv[++iArgCounter]; // extract filename
ifstream_t f(importFile); // filestream of working file
stringstream_t s; // string stream for holding JSON read from file
json::value v; // JSON read from input file
iArgCounter++; // increment arg counter
if (f) {
s << f.rdbuf(); // stream results of reading from file stream into string stream
f.close(); // close the filestream
v.parse(s); // parse the resultant string stream.
}
}
catch (web::json::json_exception excep) {
std::cout << "ERROR Parsing JSON: ";
std::cout << excep.what();
break;
}
And the following test JSON file
[
{
"Destinations":
[
{
"Domain": "127.0.0.1",
"Name": "GoogleLogin",
"Port": "8090"
}
],
"Listeners":
[
{
"Domain": "127.0.0.1",
"Name": "LoginRequest",
"Port": "8080",
"Route": "ProcessLoginRequest"
}
],
"Name": "LoginProcess",
"Routes":
[
{
"Name": "ProcessLoginRequest",
"Rules":
[{
"DestinationIfTrue": "GoogleLogin",
"LeftTerm":
{
"RuleTermType": 1,
"Value": "NETWORK"
},
"Operator": 2,
"RightTerm":
{
"RuleTermType": 0,
"Value": "NETWORK"
}
}],
"Transformations": []
}
]
}
]
The trouble is no matter what the JSON code I get the error 'Line 1, Column 2 Syntax error: Malformed token'. From what I can tell the JSON is correctly formatted with all brackets balanced.
Code is running on 64bit Windows 7.
Anyone got an idea why it thinks this (or how I can convert the stringstream_t to a string and see what it actually reads).

Answer 1

change the line
v.parse(s);
to
v = json::value::parse(s)

Answer 2

Could it be that the file is of utf16 encoding?
Or check if your json file has BOM (Byte Oder Mark) at the head by opening it with a hex editor.

Answer 3

Multiple things could go wrong here
Check if the ifstream is able to open the file correctly using the following
if(!f)
cerr << "can't open file";
If this is the case, check if name of the file and location is correct or not
Also replace
v.parse(s);
with
v = json::value::parse(s.str()) /* As parse would take string as input */