Develop Reference

Removing duplicate files upload-files

I use lodash clonedeep for uploading files.
I wrote a function that forbids uploading identical files. But if I delete some file after uploading, it still stays in state and I can't upload file with the same name.
What can I do to get the file removed from the state too?
const [files, setFiles] = useState([]);
//state to store uploaded file's name
const [fileNames, setFileNames] = useState([]);
const onSelectFile = (e) => {
try {
let fileArr = cloneDeep(files);
let promises = [];
for (let file of e.target.files) {
promises.push(
new Promise((resolve, reject) => {
const fileName = file.name
//if the file has not been already uploaded
if (!fileNames.includes(fileName)) {
//add the current fileName in state
setFileNames([fileName, ...fileNames]);
const type = file.type;
let reader = new FileReader();
reader.readAsArrayBuffer(file);
reader.onload = function (evt) {
const fileData = evt.target.result;
fileArr.push({
name: fileName,
type: type,
data: fileData,
comment: "",
id: `${new Date().getTime()}_${fileName}`,
canDelete: true
});
if (typeof props.onFileSelected == "function")
props.onFileSelected(fileArr);
resolve(true);
}
reader.onerror = function (evt) {
console.log("error reading file");
reject(false);
}
} else {
alert("File has already been uploaded");
reject(false);
}
})
);
}
Promise.all(promises).then(r => {
setFiles(fileArr);
})
}
catch(e) {
console.log(e);
}
}
I don’t know what to do, it took me 40 hours to think, but I still didn’t understand anything.

From what I can understand from your question, you aren't saving the images on disk. You also haven't included the logic you are using for deleting files. Either way, the implementation is similar.
So when a user deletes a file, assuming they are deleting by filename, we use the filter() method to only keep those that aren't the file we want to delete.
const fileNameToRemove = 'example.txt';
setFiles(files.filter(file=> file.name !== fileNameToRemove));
setFileNames(fileNames.filter(name => name !== fileNameToRemove));
So you will want to do something like this, I haven't used clonedeep like you're in this example, but it's a quick add. I have also moved the read file section into its own function, and am I returning a promise, so I can use async/await within the core upload function.
const [files, setFiles] = useState([]);
const [fileNames, setFileNames] = useState([]);
const readFileAsync = async (file) => {
return new Promise((resolve, reject) => {
const fileReader = new FileReader();
fileReader.readAsArrayBuffer(file);
fileReader.onload = () => {
resolve(fileReader.result);
}
fileReader.onerror = () => {
reject(null);
}
})
}
const onSelectFile = async (e) => {
const uploadingFiles = e.target.files;
for (const file of uploadingFiles) {
const fileName = file.name;
if (fileNames.includes(fileName)) {
console.error("File duplicate");
continue;
}
try {
const fileContentsBuffer = await readFileAsync(file);
setFiles([...files, {
name: fileName,
type: file.type,
data: fileContentsBuffer,
comment: "",
id: `${new Date().getTime()}_${fileName}`,
canDelete: true
}])
setFileNames([...fileNames, fileName]);
} catch (e) {
console.error("Error reading file");
continue;
}
}
}
const deleteFile = (fileName) => {
const fileDataToDelete = files.find((file) => {
return file.name === fileName;
})
if (!fileDataToDelete.canDelete) {
console.error('Can\'t delete file!');
return;
}
setFileNames(fileNames.filter(name => name != fileName));
setFiles(files.filter(file => file.name != fileName && file.canDelete));
}

Broadcasting to all clients with Deno websocket

I want to add notifications to an application I've developed.
Unfortunately, Deno has removed the ws package.(https://deno.land/std#0.110.0/ws/mod.ts)
That's why I'm using the websocket inside the denon itself. Since it doesn't have many functions, I have to add some things myself.
For example, sending all messages to open clients.
What I want to do is when the pdf is created, a (data, message) comes from the socket and update the notifications on the page according to the incoming data.
I keep all open clients in a Map. and when the pdf is created, I return this Map and send it to all sockets (data, message).
However, this works for one time.
server conf...
import {
path,
paths,
ctid,
} from "../deps.ts";
const users = new Map();
const sockets = new Map()
const userArr = [];
export const startNotif = (socket,req) => {
const claims = req.get("claims");
const org = req.get("org");
claims.org = org;
console.log("connected")
users.set(claims.sub, {"username":claims.sub,"socket":socket})
users.forEach((user)=>{
if(userArr.length === 0){
userArr.push(user)
}
else if(userArr.every((w)=> w.username !== user.username) )
userArr.push(user)
})
sockets.set(org, userArr)
function broadcastMessage(message) {
sockets.get(org).map((u)=>{
console.log(u.socket.readyState)
u.socket.send(message)
})
}
if (socket.readyState === 3) {
sockets.delete(uid)
return
}
const init = (msg) => {
socket.send(
JSON.stringify({
status: "creating",
})
);
};
const ondata = async (msg) => {
const upfilepath = path.join(paths.work, `CT_${msg.sid}_report.pdf`);
try {
const s=await Deno.readTextFile(upfilepath);
if(s){
socket.send(
JSON.stringify({
status: "end",
})
);
} else {
socket.send(
JSON.stringify({
status: "creating",
})
);
}
} catch(e) {
if(e instanceof Deno.errors.NotFound)
console.error('file does not exists');
}
};
const end = () => {
try {
const endTime = Date.now()
const msg = "Your PDF has been created"
const id = ctid(12) // random id create
broadcastMessage(
JSON.stringify({
id: id,
date: endTime,
status: "done",
message: msg,
read: 'negative',
action: 'pdf'
})
);
} catch (e) {
console.log(400, "Cannot send.", e);
}
}
socket.onmessage = async (e) => {
const cmd = JSON.parse(e.data);
if(cmd.bid === 'start'){
await init(cmd)
}
if(!cmd.bid && cmd.sid){
await ondata(cmd)
}
if(cmd.bid === 'end'){
await end();
}
}
socket.onerror = (e) => {
console.log(e);
};
}
client conf...
export const webSocketHandler = (request) =>
new Promise((res, rej) => {
let url;
if (!process.env.NODE_ENV || process.env.NODE_ENV === 'development') {
url = `http://localhost:8080/api/notifications/ws`.replace('http', 'ws');
} else {
url = `${window.location.origin}/api/notifications/ws`.replace('http', 'ws');
}
const token = JSON.parse(sessionStorage.getItem('token'));
const orgname = localStorage.getItem('orgname');
const protocol = `${token}_org_${orgname}`;
const socket = new WebSocket(url, protocol);
const response = Object.create({});
socket.onopen = function () {
socket.send(
JSON.stringify({
bid: 'start',
})
);
};
socket.onmessage = function (event) {
response.data = JSON.parse(event.data);
if (response.data.status === 'creating') {
socket.send(
JSON.stringify({
sid: request.sid,
})
);
} else if (response.data.status === 'end') {
socket.send(
JSON.stringify({
bid: 'end',
})
);
} else if (response.data.status === 'done') {
try {
res(response);
} catch (err) {
rej(err);
}
}
};
socket.onclose = function (event) {
response.state = event.returnValue;
};
socket.onerror = function (error) {
rej(error);
};
});
onclick function of button I use in component...
const donwloadReport = async (type) => {
const query = `?sid=${sid}&reportType=${type}`;
const fileName = `CT_${sid}_report.${type}`;
try {
type === 'pdf' && setLoading(true);
const response = await getScanReportAction(query);
const request = {
sid,
};
webSocketHandler(request)
.then((data) => {
console.log(data);
dispatch({
type: 'update',
data: {
id: data.data.id,
date: data.data.date,
message: data.data.message,
action: data.data.action,
read: data.data.read,
},
});
})
.catch((err) => {
console.log(err);
});
if (type === 'html') {
downloadText(response.data, fileName);
} else {
const blobUrl = await readStream(response.data);
setLoading(false);
downloadURL(blobUrl, fileName);
}
} catch (err) {
displayMessage(err.message);
}
};
Everything works perfectly the first time. When I press the download button for the pdf, the socket works, then a data is returned and I update the notification count with the context I applied according to this data.
Later I realized that this works in a single tab. When I open a new client in the side tab, my notification count does not increase. For this, I wanted to keep all sockets in Map and return them all and send a message to each socket separately. But in this case, when I press the download button for the second time, no data comes from the socket.
Actually, I think that I should do the socket initialization process on the client in the context. When you do this, it starts the socket 2 times in a meaningless way.
In summary, consider an application with organizations and users belonging to those organizations. If the clients of A, B, C users belonging to X organization are open at the same time and user A pressed a pdf download button, I want A, B, C users to be notified when the pdf is downloaded.
I would be very grateful if someone could show me a way around this issue.

Have you looked at the BroadcastChannel API? Maybe that could solve your issue. See for example:
Deno specific: https://medium.com/deno-the-complete-reference/broadcast-channel-in-deno-f76a0b8893f5
Web/Browser API: https://developer.mozilla.org/en-US/docs/Web/API/Broadcast_Channel_API

Upload byte array from axios to Node server

Background
Javascript library for Microsoft Office add-ins allows you to get raw content of the DOCX file through getFileAsync() api, which returns a slice of up to 4MB in one go. You keep calling the function using a sliding window approach till you have reed entire content. I need to upload these slices to the server and the join them back to recreate the original DOCX file.
My attempt
I'm using axios on the client-side and busboy-based express-chunked-file-upload middleware on my node server. As I call getFileAsync recursively, I get a raw array of bytes that I then convert to a Blob and append to FormData before posting it to the node server. The entire thing works and I get the slice on the server. However, the chunk that gets written to the disk on the server is much larger than the blob I uploaded, normally of the order of 3 times, so it is obviously not getting what I sent.
My suspicion is that this may have to do with stream encoding, but the node middleware does not expose any options to set encoding.
Here is the current state of code:
Client-side
public sendActiveDocument(uploadAs: string, sliceSize: number): Promise<boolean> {
return new Promise<boolean>((resolve) => {
Office.context.document.getFileAsync(Office.FileType.Compressed,
{ sliceSize: sliceSize },
async (result) => {
if (result.status == Office.AsyncResultStatus.Succeeded) {
// Get the File object from the result.
const myFile = result.value;
const state = {
file: myFile,
filename: uploadAs,
counter: 0,
sliceCount: myFile.sliceCount,
chunkSize: sliceSize
} as getFileState;
console.log("Getting file of " + myFile.size + " bytes");
const hash = makeId(12)
this.getSlice(state, hash).then(resolve(true))
} else {
resolve(false)
}
})
})
}
private async getSlice(state: getFileState, fileHash: string): Promise<boolean> {
const result = await this.getSliceAsyncPromise(state.file, state.counter)
if (result.status == Office.AsyncResultStatus.Succeeded) {
const data = result.value.data;
if (data) {
const formData = new FormData();
formData.append("file", new Blob([data]), state.filename);
const boundary = makeId(12);
const start = state.counter * state.chunkSize
const end = (state.counter + 1) * state.chunkSize
const total = state.file.size
return await Axios.post('/upload', formData, {
headers: {
"Content-Type": `multipart/form-data; boundary=${boundary}`,
"file-chunk-id": fileHash,
"file-chunk-size": state.chunkSize,
"Content-Range": 'bytes ' + start + '-' + end + '/' + total,
},
}).then(async res => {
if (res.status === 200) {
state.counter++;
if (state.counter < state.sliceCount) {
return await this.getSlice(state, fileHash);
}
else {
this.closeFile(state);
return true
}
}
else {
return false
}
}).catch(err => {
console.log(err)
this.closeFile(state)
return false
})
} else {
return false
}
}
else {
console.log(result.status);
return false
}
}
private getSliceAsyncPromise(file: Office.File, sliceNumber: number): Promise<Office.AsyncResult<Office.Slice>> {
return new Promise(function (resolve) {
file.getSliceAsync(sliceNumber, result => resolve(result))
})
}
Server-side
This code is totally from the npm package (link above), so I'm not supposed to change anything in here, but still for reference:
makeMiddleware = () => {
return (req, res, next) => {
const busboy = new Busboy({ headers: req.headers });
busboy.on('file', (fieldName, file, filename, _0, _1) => {
if (this.fileField !== fieldName) { // Current field is not handled.
return next();
}
const chunkSize = req.headers[this.chunkSizeHeader] || 500000; // Default: 500Kb.
const chunkId = req.headers[this.chunkIdHeader] || 'unique-file-id'; // If not specified, will reuse same chunk id.
// NOTE: Using the same chunk id for multiple file uploads in parallel will corrupt the result.
const contentRangeHeader = req.headers['content-range'];
let contentRange;
const errorMessage = util.format(
'Invalid Content-Range header: %s', contentRangeHeader
);
try {
contentRange = parse(contentRangeHeader);
} catch (err) {
return next(new Error(errorMessage));
}
if (!contentRange) {
return next(new Error(errorMessage));
}
const part = contentRange.start / chunkSize;
const partFilename = util.format('%i.part', part);
const tmpDir = util.format('/tmp/%s', chunkId);
this._makeSureDirExists(tmpDir);
const partPath = path.join(tmpDir, partFilename);
const writableStream = fs.createWriteStream(partPath);
file.pipe(writableStream);
file.on('end', () => {
req.filePart = part;
if (this._isLastPart(contentRange)) {
req.isLastPart = true;
this._buildOriginalFile(chunkId, chunkSize, contentRange, filename).then(() => {
next();
}).catch(_ => {
const errorMessage = 'Failed merging parts.';
next(new Error(errorMessage));
});
} else {
req.isLastPart = false;
next();
}
});
});
req.pipe(busboy);
};
}
Update
So it looks like I have found the problem at least. busboy appears to be writing my array of bytes as text in the output file. I get 80,75,3,4,20,0,6,0,8,0,0,0,33,0,44,25 (as text) when I upload the array of bytes [80,75,3,4,20,0,6,0,8,0,0,0,33,0,44,25]. Now need to figure out how to force it to write it as a binary stream.

Figured out. Just in case it helps anyone, there was no problem with busboy or office.js or axios. I just had to convert the incoming chunk of data to Uint8Array before creating a blob from it. So instead of:
formData.append("file", new Blob([data]), state.filename);
like this:
const blob = new Blob([ new Uint8Array(data) ])
formData.append("file", blob, state.filename);
And it worked like a charm.

Convert image path to blob react native

Problem
I am trying to create an app with react native and firebase. One of the features I would like for this app is the ability to upload images. I am having some trouble uploading the images to firebase storage though. I am using expo's image picker to find the path of the image that the user wants to upload, but once I have the path I don't know how to convert that to something I can upload to firebase.
Can somebody help me convert the path of an image to something I can upload to firebase storage with react native?
What I've tried
I tried using:
_pickImage = async () => {
let result = await ImagePicker.launchImageLibraryAsync({
MediaTypeOptions: 'Images',
quality: 0.4,
_uploadAsByteArray = async (pickerResultAsByteArray, progressCallback) => {
try {
var metadata = {
contentType: 'image/jpeg',
};
var storageRef = firebase.storage().ref();
var ref = storageRef.child('images/'+expoID+'/'+this.state.time)
let uploadTask = ref.put(pickerResultAsByteArray, metadata)
uploadTask.on('state_changed', function (snapshot) {
progressCallback && progressCallback(snapshot.bytesTransferred / snapshot.totalBytes)
var progress = (snapshot.bytesTransferred / snapshot.totalBytes) * 100;
console.log('Upload is ' + progress + '% done');
}, function (error) {
console.log("in _uploadAsByteArray ", error)
}, function () {
var downloadURL = uploadTask.snapshot.downloadURL;
console.log("_uploadAsByteArray ", uploadTask.snapshot.downloadURL)
this.setState({imageUploaded:true})
});
} catch (ee) {
console.log("when trying to load _uploadAsByteArray ", ee)
}
}
convertToByteArray = (input) => {
var binary_string = this.atob(input);
var len = binary_string.length;
var bytes = new Uint8Array(len);
for (var i = 0; i < len; i++) {
bytes[i] = binary_string.charCodeAt(i);
}
return bytes
}
atob = (input) => {
const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
let str = input.replace(/=+$/, '');
let output = '';
if (str.length % 4 == 1) {
throw new Error("'atob' failed: The string to be decoded is not correctly encoded.");
}
for (let bc = 0, bs = 0, buffer, i = 0;
buffer = str.charAt(i++);
~buffer && (bs = bc % 4 ? bs * 64 + buffer : buffer,
bc++ % 4) ? output += String.fromCharCode(255 & bs >> (-2 * bc & 6)) : 0
) {
buffer = chars.indexOf(buffer);
}
return output;
}
uploadImage(bsfdata){
this.setState({imageUploaded:false})
this._uploadAsByteArray(this.convertToByteArray(bsfdata), (progress) => {
this.setState({ progress:progress })
})
}
base64:true,
});
/* if (!result.cancelled) {
this.setState({ image: result.uri });
let formData = new FormData();
formData.append('photo', {
uri,
name: `photo.${fileType}`,
type: `image/${fileType}`,
});}*/
this.uploadImage(result.base64);
};
}
I've tried it with the commented code added, which doesn't upload anything, and I've tried it with how the code is now, which gives me the error Can currently only create a Blob from other Blobs, and the uploading progress never gets above 0%.

If you are using expo (>=26), then you can do it easily with the following lines of code.
uploadImage = async(imageUri) => {
const response = await fetch(imageUri);
const blob = await response.blob();
var ref = firebase.storage().ref().child("image.jpg");
return ref.put(blob);
}
Reference: https://youtu.be/KkZckepfm2Q

Refer this link - https://github.com/dailydrip/react-native-firebase-storage/blob/master/src/App.js#L43-L69
Following block of code is working fine.
uploadImage(uri, mime = 'application/octet-stream') {
return new Promise((resolve, reject) => {
const uploadUri = Platform.OS === 'ios' ? uri.replace('file://', '') : uri
let uploadBlob = null
const imageRef = FirebaseClient.storage().ref('images').child('image_001')
fs.readFile(uploadUri, 'base64')
.then((data) => {
return Blob.build(data, { type: `${mime};BASE64` })
})
.then((blob) => {
uploadBlob = blob
return imageRef.put(blob, { contentType: mime })
})
.then(() => {
uploadBlob.close()
return imageRef.getDownloadURL()
})
.then((url) => {
resolve(url)
})
.catch((error) => {
reject(error)
})
})
}

You need to install rn-fetch-blob module:
npm install --save rn-fetch-blob
Then, do the following:
import RNFetchBlob from 'rn-fetch-blob';
const Blob = RNFetchBlob.polyfill.Blob;
const fs = RNFetchBlob.fs;
window.XMLHttpRequest = RNFetchBlob.polyfill.XMLHttpRequest;
window.Blob = Blob;
function uploadImage(path) {
const imageFile = RNFetchBlob.wrap(path);
// 'path/to/image' is where you wish to put your image in
// the database, if you would like to put it in the folder
// 'subfolder' inside 'mainFolder' and name it 'myImage', just
// replace it with 'mainFolder/subfolder/myImage'
const ref = firebase.storage().ref('path/to/image');
var uploadBlob = null;
Blob.build(imageFile, { type: 'image/jpg;' })
.then((imageBlob) => {
uploadBlob = imageBlob;
return ref.put(imageBlob, { contentType: 'image/jpg' });
})
.then(() => {
uploadBlob.close();
return ref.getDownloadURL();
})
.((url) => {
// do something with the url if you wish to
})
.catch(() => {
dispatch({
type: UPDATE_PROFILE_INFO_FAIL,
payload: 'Unable to upload profile picture, please try again'
});
});
}
Please do ask if there's any part of the code that you don't understand. To upload multiple images, simply wrap this code with a for loop. Or if you want to make sure that every image is uploaded without any error, use Promise

Not sure whom this might help, but if you're using MediaLibrary to load images from the gallery, then the uri comes in the format of uri = file:///storage/emulated/0/DCIM/Camera/filename.jpg
In this case, using fetch(uri) didn't help me get the blob.
But if you use fetch(uri.replace("file:///","file:/")) and then follow #sriteja Sugoor's answer, you'll be able to upload the file blob.

const Blob = RNFetchBlob.polyfill.Blob;
const fs = RNFetchBlob.fs;
let uploadBlob;
await fs
.readFile(params?.file.path, 'base64')
.then((data) => {
return Blob.build(data, {type: `BASE64`});
})
.then((blob) => {
uploadBlob = blob;
console.log(uploadBlob, 'uploadBlob');
});

CSV import in neo4j using node.js

I'm trying to import csv file into neo4j using node.js. I have to insert data into multiple collection/table, so I have to insert data using node.js script. But my problem is, I can't prevent data duplication when inserting csv data.
Sample CSV data:
name
-------------
Afghanistan
Afghanistan
Aland
Albania
Albania
Bangladesh
Bangladesh
index.js
cp = require('child_process');
child = cp.fork(__dirname + "/background-import-csv-file.js");
child.on('message', function(msg) {
console.log("background-insert-process said : ", msg);
});
file = path.resolve(__dirname, `./file/simplemaps.csv`);
child.send(file);
In background-import-csv-file.js, I have write code in two different way.
First Promise based (background-import-csv-file.js) :
cp = require('child_process');
csv = require('fast-csv');
Q = require('q');
DB = require("./common/driver");
Country = require('./collection/country');
process.on("message", (file) => {
stream = fs.createReadStream(file);
csv
.fromStream(stream, { headers: true })
.on("data", function(data) {
let countryData = { "name": data.name };
neo = new DB();
country = new Country(neo);
country.insert(countryData)
.then(resp => process.send(resp.msg) )
.catch(err => process.send(err) )
})
.on("end", () => process.send("file read complete") );
});
./collection/country.js:
Q = require('q');
Country = function Country(neo) {
this.country = "Country"; this.neo = neo;
};
Country.prototype.find = function find(filters) {
query = `MATCH (a:Country { name: '${filters.name}' } ) RETURN {country:properties(a)}`;
return this.neo.run(query, filters).then(resp => resp);
}
Country.prototype.create = function create(data) {
query = `CREATE (ax:Country { name: '${data.name}' } ) RETURN ax `;
return this.neo.run(query, {}).then(resp => resp[0].properties).catch(err => err)
}
Country.prototype.insert = function insert(country) {
filter = { name: country.name };
return Q(this.find(filter))
.then(resp => resp.length > 0 ? Q.resolve({ msg: `country: [${country.name}] is already exist` }) : Q.resolve(this.create(country)) )
.then(resp => resp)
.catch(e => Q.reject(e));
}
module.exports = Country;
./common/driver.js
neo4j = require('neo4j-driver').v1;
function DB() {
this.driver = neo4j.driver(); this.session = this.driver.session();
}
DB.prototype.run = function run(query, data) {
return this.session.run(query, data)
.then(response => response.records.map(
record => record._fields[0] ?
record._fields.length ? record._fields[0] : {} : {}
) ).catch(err => new Error(err) );
}
module.exports = DB;
When I run index.js in terminal, In database, I have 2 Afghanistan, 1 Aland, 2 Albania and 2 Bangladesh. But I need 1 Afghanistan, 1 Aland, 1 Albania and 1 Bangladesh in my database. When I analyze code, than found that before inserting data, I'm checking data ( Country.prototype.find = function find(filters)) if it is already exist or not, but it always return empty result. That why it insert multiple data. If I run index.js again, then no new data is inserted into database. To solve this problem, I've tried following CQL :
MERGE (c:Country { name: '${data.name}' } ) RETURN c
It is inserted unique data, but It kill so much time. Then I have written the following code:
Event-driven (background-import-csv-file.js) :
process.on("message", (file) => {
stream = fs.createReadStream(file);
csv
.fromStream(stream, { headers: true })
.on("data", function(data) {
countryData = { "name": data.name };
neo = new DB();
country = new Country(neo);
country.find(countryData);
country.on('find', resp => resp.length > 0 ? Q.resolve({ msg: `country: [${country.name}] is already exist` }) : Q.resolve(country.create(countryData)) );
country.on('create', resp => console.log(resp) );
})
.on("end", () => process.send("file read complete") );
});
./collection/country.js:
EventEmitter = require('events').EventEmitter;
util = require('util');
Country = function Country(neo) {
this.neo = neo; EventEmitter.call(this);
};
util.inherits(Country, EventEmitter);
Country.prototype.find = function find(filters) {
query = `MATCH (a:Country { name: '${filters.name}' } ) RETURN {country:properties(a)}`;
return this.neo.run(query, {}).then(resp => this.emit('find', resp));
}
Country.prototype.create = function create(data) {
query = `CREATE (ax:Country { name: '${data.name}' } ) RETURN ax `;
return this.neo.run(query, {}).then(resp => this.emit('create', resp[0].properties)).catch(err => err)
}
And this time, it shows same result. What am I missing? Any suggestion will be very helpfull.
NB: I'm using fast-csv for csv parsing and Q for promise.

Actually I can imagine the following solutions:
Modify the CSV file itself with programming language(like node.js) to remove the duplicate lines with the same name.
Add the neo4j unique constrains
CREATE CONSTRAINT ON (c:Country) ASSERT c.name IS UNIQUE
Involve the middleware, like a queue which to prevent the duplicate items, for this, you need to define you own message structure and duplicate arithmetic.
above.

My problem was, in csv file parsing, it was so fast (event-driven) it wasn't wait to finish insert data into database. So I have to pause file parsing and then resume it.
I solve my problem using the following code:
Promise based (background-import-csv-file.js) :
cp = require('child_process');
csv = require('fast-csv');
Q = require('q');
DB = require("./common/driver");
Country = require('./collection/country');
process.on("message", (file) => {
stream = fs.createReadStream(file);
csvstream = csv
.fromStream(stream, { headers: true })
.on("data", function(data) {
csvstream.pause(); // pause the csv file parsing
countryData = { "name": data.name };
neo = new DB();
country = new Country(neo);
country.insert(countryData)
.then(resp => {
process.send(resp.msg);
neo.close();
return csvstream.resume(); // after completing db process, resume
})
.catch(err => {
process.send(err);
return csvstream.resume(); // if failed, then resume
});
})
.on("end", () => process.send("file read complete") );
});