I am getting the data from my JSON file through this code:
var content = await rootBundle.loadString("json/story1.json");
decodedContent = json.decode(content);
And I would like to be able to store an integer inside the story1.json file.
Related
I have data come from a device to my flutter application via bluetooth.
I have lists that are displayed one by one on alerts. I want to collect data on all the alerts and then save it on csv file.
The problem is that there are lot of files created and every file contain juste one list this mean that for every alert there is a file created.
this is the code:
setupMode.generateCsv((message) async {
List<List<String>> data = [
["No.", "X", " Y", "Z", "Z"],
[message.data[1], message.data[2], message.data[3], message.data[4]],
];
String csvData = ListToCsvConverter().convert(data);
final String directory = (await getApplicationSupportDirectory()).path;
final path = "$directory/csv-${DateTime.now()}.csv";
print(path);
final File file = File(path);
await file.writeAsString(csvData);
print("file saved");
print(csvData.length);
});
}
I want to collect all the data and store it on one file.
In order to write into one file, there are two things you need to change:
File name:
final path = "$directory/csv-${DateTime.now()}.csv";
This creates a new file every time you call it. You should use the same file name, e.g.:
final path = "$directory/csv-alert-data.csv";
The second change is the write type:
await file.writeAsString(csvData,mode:FileMode.append);
This will append the new data to the end of the existing CSV file.
I am gathering accelerometer data from my phone using the sensors package, adding that data to a List<AccelerometerEvent>, and then combining that data into a (csv) String so I can use file.writeAsString() to save this data as a csv file. The problem I am having is that it takes too long to combine the data into a string.
For example:
List length : 28645
Milliseconds to combine into csv string: 113580
Code:
for (AccelerometerEvent event in history) {
dataString = dataString + '${event.timestamp},${event.x},${event.y},${event.z}\n';
}
What would be a more efficient way to do this?
Should I even combine the data into a string, or is there a better way to save this data to a file?
Thanks
Create a file object
write first line with column names, and after that each row (after \n) will be an event
See: FileMode.append
Will add new strings without replacing existing string in file
File file = File('events.csv');
file.writeAsStringSync('TIMESTAMP, X, Y, Z\n', mode: FileMode.append);
for (AccelerometerEvent event in history) {
final x = event.x;
final y = event.y;
final z = event.z;
final timestamp = event.timestamp;
String data = '$timestamp, $x, $y, $z';
file.writeAsStringSync('$data\n', mode: FileMode.append);
}
I'm using a json file to store my data and I need to show some of it on the screen.
For example, when I make a simple text widget and use this string:
Text("a\u2081")
It shows "a" with a subscripted "1".
The problem is that when I load it from a json file it just shows "a\u2081".
This is how I load the data:
var myData = await rootBundle.loadString("data/my_data.json");
var data = await json.decode(myData.toString());
I'm storing the values in objects:
Text(TestReport[i].text) // where TestReport[i].text = "a\u2081"
Is there a way how to show the subscript?
I have:
Raw xml filled by a select query.This xml transformed into a HL7
message
One of the tags of this xml represents a clob column from a table in
the database
I mapped this data (from edit transformer section) as a variable.
Now I am trying to convert this variable into a base64 string then
replace it in my transformed hl7 message.
5.I tried this conversion on a destination channel which is a javascript writer.
I read and tried several conversion methods like
Packages.org.apache.commons.codec.binary.Base64.encodeBase64String();
I have got only error messages like :
EvaluatorException: Can't find method org.apache.commons.codec.binary.Base64.encodeBase64String(java.lang.String);
Code piece:
var ads=$('V_REPORT_CLOB');
var encoded = Packages.org.apache.commons.codec.binary.Base64.encodeBase64String(ads.toString());
It is pretty clear that I am a newbie on that.How can I manage to do this conversion ?
Here is what I use for Base64 encoding a string with your var substituted.
//Encode Base 64//
var ads = $('V_REPORT_CLOB');
var adsLength = ads.length;
var base64Bytes = [];
for(i = 0; i < adsLength;i++){
base64Bytes.push(ads.charCodeAt(i));
}
var encodedData = FileUtil.encode(base64Bytes);
I'm using Papa.unparse() to convert a JSON object to csv then downloading the file. The method fails with:
"allocation size overflow papaparse.min.js:6:1580"
This happens in firefox when there's > than 500,000 items to unparse in the JSON array.
The Papa.parse() method allows you to stream data from a file. Is there any similar approach you can take for Papa.unparse()?
You don't need PapaParse to do this.
The allocation size overflow problem is from converting your 500,000 rows into 500,000 strings and concatenating them together to form one massive string to create the CSV file with. JavaScript creates a new String when you concatenate one or more together, and eventually you run out of memory and crash.
The solution is to use TextEncoder to encode your strings into utf-8 (or whatever you need) ArrayBuffers, push each one into a giant array, and then use that array to create your file.
Here's some rough code for how you might do that:
var textEncoder = new TextEncoder("utf-8");
var headers = ["header1","header2","header3"];
var row1 = ["column1-1","column1-2","column1-3"];
var row2 = ["column2-1","column-2-2","column2-3"];
var data = [headers,row1,row2];
var arrayBuffers = [];
var csvString = '';
var encodedString = null;
var file = null;
for(var x=0;x<data.length;x++){
csvString = data[x].join(",").concat('\r\n');
encodedString = textEncoder.encode(csvString);
arrayBuffers.push(encodedString);
}
file = new File(arrayBuffers,"yourCsvFile.csv",{ type: "text/csv" });
I use text-encoding for a TextEncoder polyfill, and presumably if you're trying to Papa.unparse you've got FileAPI already.