I am using this code to add to my existing JSON file. However It completely overrides my JSON file and just puts one JSON object in it when I would just like to add another item to the list of items in my JSON file. How would I fix this?
Json::Value root;
root[h]["userM"] = m;
root[h]["userT"] = t;
root[h]["userF"] = f;
root[h]["userH"] = h;
root[h]["userD"] = d;
Json::StreamWriterBuilder builder;
std::unique_ptr<Json::StreamWriter> writer(builder.newStreamWriter());
std::ofstream outputFileStream("messages.json");
writer-> write(root, &outputFileStream);
My recommendation is
Load the file into a Json::Value
Add or change whatever fields you want
Overwrite the original file with the updated Json::Value
Doing this is going to be the least error-prone method, and it'll work quickly unless you have a very large Json file.
How to read in the entire file
This is pretty simple! We make the root, then just use the >> operator to read in the file.
Json::Value readFile(std::istream& file) {
Json::Value root;
Json::Reader reader;
bool parsingSuccessful = reader.parse( file, root );
if(not parsingSuccessful) {
// Handle error case
}
return root;
}
See this documentation here for more information
Related
After successfully compress the folder, here is my situation :
If append = true and overWrite = false I have to check whether if the target zip file exists or not if existed I will check the existed zip file which files it doesn't contain and append new file from the source folder to it.
My question is:
How can I open the zip file and put it to the compress object? or which others library in Poco should I use to open zip stream? I'm trying to use std::ifstream but Poco::zip::Compress doesn't seem to receive an std::ifstream
I surely have to modify the Poco source code itself to match with my requirement. Thanks in advance.
void ZipFile(string source, string target, List extensions, bool append, bool overWrite)
{
Poco::File tempFile(source);
if (tempFile.exists())
{
if (Poco::File(target).exists() && append && !overWrite) {
fs::path targetPath = fs::path(target);
std::ifstream targetFileStream(targetPath.string(), std::ios::binary);
std::ofstream outStream(target, ios::binary);
CompressEx compress(outStream, false, false);
if (tempFile.isDirectory())
{
Poco::Path sourceDir(source);
sourceDir.makeDirectory();
compress.addRecursive(sourceDir, Poco::Zip::ZipCommon::CompressionMethod::CM_AUTO,
Poco::Zip::ZipCommon::CL_NORMAL, false);
}
else if (tempFile.isFile())
{
Poco::Path path(tempFile.path());
compress.addFile(path, path.getFileName(), Poco::Zip::ZipCommon::CompressionMethod::CM_AUTO,
Poco::Zip::ZipCommon::CL_NORMAL);
}
compress.close(); // MUST be done to finalize the Zip file
outStream.close();
}
}
No need to modify the Poco source code. Poco allows you to get the contents of an archive and add files to it.
First, open the target archive to check which files are already in there:
Poco::ZipArchive archive(targetFileStream);
Then collect all files you want to add, that are not in the archive, yet:
std::vector<fs::path> files;
if (fs::is_directory(source)) {
for(auto &entry : fs::recursive_directory_iterator())
// if entry is file and not in zip
if (fs::is_regular_file(entry)
&& archive.findHeader(fs::relative(entry.path, source)) == archive.headerEnd()) {
files.push_back(entry.path);
}
} else if (fs::is_regular_file(entry)
&& archive.findHeader(source) == archive.headerEnd()) {
files.push_back(source);
}
Finally, add the files to your zip
Poco::Zip::ZipManipulator manipulator(target, false);
for(auto &file : files)
manipulator.addFile(fs::relative(file, source), file,
Poco::Zip::ZipCommon::CompressionMethod::CM_AUTO,
Poco::Zip::ZipCommon::CL_NORMAL);
I had no opportunity to test this. So try it out and see what needs to be done to make it work.
I want to read a xml file or text file in zip archive without extracting it from the archive. Can I do it directly without extracting it from the zip archive?
Yes you can, wxZipInputStream should be what you are looking for.
wxZipInputStream zip(in);
while (entry.reset(zip.GetNextEntry()), entry.get() != NULL) {
wxString name = entry->GetName();
name = strPageName.BeforeLast('\\') + wxFileName::GetPathSeparator() + name;
zip.OpenEntry(*entry.get());
wxFileOutputStream file(name);
if (!file) {
wxLogError(_T("Can not create file '") + name + _T("'."));
break;
}
zip.Read(file);
I tried using wxZipInputStream. Yes, I can read files after extracting from the archive. I like to know whether I can read those files without extracting from the zip archive.
wxFileSystem::AddHandler(new wxZipFSHandler);
wxFileSystem fs;
wxFSFile *zip = fs.OpenFile( "d:\\test.zip#zip:test.txt");
if(zip!=NULL)
{
wxInputStream *in = zip->GetStream();
if ( in != NULL )
{
wxFileOutputStream out( "d:\\testout.txt" );
out.Write(*in);
out.Close();
}
delete zip;
}
Yes, we can read the zip file directly from the archive. The above is the sample code.
I'm using RapidXML to parse XML files and read nodes content but I don't want to read values inside a node, I need to read the content of specific XML nodes "as XML" not as parsed values.
Example :
<node1>
<a_lot_of_xml>
< .... >
</a_lot_of_xml>
</node1>
I need to get the content of node1 as :
<a_lot_of_xml>
< .... >
</a_lot_of_xml>
What I tired :
I tried something but its not really good in my opinion, its about to put in node1, the path of an other xml file to read, I did like this :
<file1ToRead>MyFile.xml</file1ToRead>
And then my c++ code is the following :
ifstream file(FileToRead);
stringstream buffer; buffer << file.rdbuf();
But the problem is users will have a lot of XML files to maintain and I just want to use one xml file.
I think "a lot of XML files" is a better way, so you have a directory of all xml files, you can read the xml file when you need it, good for performance.
Back to the problem, can use the rapidxml::print function to get the xml format.
bool test_analyze_xml(const std::string& xml_path)
{
try
{
rapidxml::file<> f_doc(xml_path.c_str());
rapidxml::xml_document<> xml_doc;
xml_doc.parse<0>(const_cast<char*>(f_doc.data()));
rapidxml::xml_node<>* node_1 = xml_doc.first_node("node1");
if(node_1 == NULL)
{
return false;
}
rapidxml::xml_node<>* plain_txt = node_1->first_node("a_lot_of_xml");
if (plain_txt == NULL)
{
return false;
}
std::string xml_data;
rapidxml::print(std::back_inserter(xml_data), *plain_txt, rapidxml::print_no_indenting); //the xml_data is XML format.
}
catch (...)
{
return false;
}
return true;
}
I'm unfamiliar with rapidxml, but I have done this with tinyxml2. The trick is to read out node1 and then create a new XMLDoc (using tinyxml2 terms here) that contains everything inside of node1. From there, you can use their XMLPrinter class to convert your new XMLDoc (containing everything in node1) to a string.
tinyxml2 is a free download.
Sometimes I need to ensure I'm not overwriting an existing file when saving some data, and I'd like to use a function that appends a suffix similar to how a browser does it - if dir/file.txt exists, it becomes dir/file (1).txt.
This is an implementation I've made, that uses Qt functions:
// Adds a unique suffix to a file name so no existing file has the same file
// name. Can be used to avoid overwriting existing files. Works for both
// files/directories, and both relative/absolute paths. The suffix is in the
// form - "path/to/file.tar.gz", "path/to/file (1).tar.gz",
// "path/to/file (2).tar.gz", etc.
QString addUniqueSuffix(const QString &fileName)
{
// If the file doesn't exist return the same name.
if (!QFile::exists(fileName)) {
return fileName;
}
QFileInfo fileInfo(fileName);
QString ret;
// Split the file into 2 parts - dot+extension, and everything else. For
// example, "path/file.tar.gz" becomes "path/file"+".tar.gz", while
// "path/file" (note lack of extension) becomes "path/file"+"".
QString secondPart = fileInfo.completeSuffix();
QString firstPart;
if (!secondPart.isEmpty()) {
secondPart = "." + secondPart;
firstPart = fileName.left(fileName.size() - secondPart.size());
} else {
firstPart = fileName;
}
// Try with an ever-increasing number suffix, until we've reached a file
// that does not yet exist.
for (int ii = 1; ; ii++) {
// Construct the new file name by adding the unique number between the
// first and second part.
ret = QString("%1 (%2)%3").arg(firstPart).arg(ii).arg(secondPart);
// If no file exists with the new name, return it.
if (!QFile::exists(ret)) {
return ret;
}
}
}
QTemporaryFile can do it for non-temporary files, despite its name:
QTemporaryFile file("./foobarXXXXXX.txt");
file.open();
// now the file should have been renamed to something like ./foobarQSlkDJ.txt
file.setAutoRemove(false);
// now the file will not be removed when QTemporaryFile is deleted
A better solution is to use GUID
Or you can generate a hash based on bytes collected from within a file, either randomly or based on some data property that is fairly unique from file to file.
I know how to create a complete dom from an xml file just using XercesDOMParser:
xercesc::XercesDOMParser parser = new xercesc::XercesDOMParser();
parser->parse(path_to_my_file);
parser->getDocument(); // From here on I can access all nodes and do whatever i want
Well, that works... but what if I'd want to parse a string? Something like
std::string myxml = "<root>...</root>";
xercesc::XercesDOMParser parser = new xercesc::XercesDOMParser();
parser->parse(myxml);
parser->getDocument(); // From here on I can access all nodes and do whatever i want
I'm using version 3. Looking inside the AbstractDOMParser I see that parse method and its overloaded versions, only parse files.
How can I parse from a string?
Create a MemBufInputSource and parse that:
xercesc::MemBufInputSource myxml_buf(myxml.c_str(), myxml.size(),
"myxml (in memory)");
parser->parse(myxml_buf);
Use the following overload of XercesDOMParser::parse():
void XercesDOMParser::parse(const InputSource& source);
passing it a MemBufInputSource:
MemBufInputSource src((const XMLByte*)myxml.c_str(), myxml.length(), "dummy", false);
parser->parse(src);
Im doing it another way. If this is incorrect, please tell me why. It seems to work.
This is what parse expects:
DOMDocument* DOMLSParser::parse(const DOMLSInput * source )
So you need to put in a DOMLSInput instead of a an InputSource:
xercesc::DOMImplementation * impl = xercesc::DOMImplementation::getImplementation();
xercesc::DOMLSParser *parser = (xercesc::DOMImplementationLS*)impl)->createLSParser(xercesc::DOMImplementation::MODE_SYNCHRONOUS, 0);
xercesc::DOMDocument *doc;
xercesc::Wrapper4InputSource source (new xercesc::MemBufInputSource((const XMLByte *) (myxml.c_str()), myxml.size(), "A name");
parser->parse(&source);
You may use MemBufInputSource as found in the xercesc/framework/MemBufInputSource.cpp, and the header file, MemBufInputSource.hpp contains extensive documentation, as similar to answers above:
#include <xercesc/framework/MemBufInputSource.hpp>
char* myXMLBufString = "<root>hello xml</root>";
MemBufInputSource xmlBuf((const XMLByte*)myXMLBufString, 23, "myXMLBufName", false);
But take note, this doesn't seem to work unless you first initialize the system, as below (taken from the xerces-c-3.2.3/samples/src/SAX2Count/SAX2Count.cpp)
bool recognizeNEL = false;
char localeStr[64];
memset(localeStr, 0, sizeof localeStr);
// Initialize the XML4C2 system
try {
if (strlen(localeStr)) {
XMLPlatformUtils::Initialize(localeStr);
} else {
XMLPlatformUtils::Initialize();
}
if (recognizeNEL) {
XMLPlatformUtils::recognizeNEL(recognizeNEL);
}
} catch (const XMLException& toCatch) {
XERCES_STD_QUALIFIER cerr << "Error during initialization! Message:\n"
<< StrX(toCatch.getMessage()) << XERCES_STD_QUALIFIER endl;
return 1;
}
Of course reading a file wouldn't require thinking about this type of prep since you just pass a file path to the program which the parser takes. So for those experiencing seg faults, this could be the answer.