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VisualizaçõesHow can I write a Map object to a CSV file with Node JS?
I have a map:
const map = new Map()
In this map I have the values:
{
'contract' => [ 'MetaCoin.sol', 'MetaCoin.sol', 'MetaCoin.sol', 'MetaCoin.sol' ],
'hash' => [ '1bb0ff1c', '330f7461', '07c815a6', '8166ca06' ],
'operator' => [ 'AOR', 'AOR', 'AOR', 'AOR' ],
'TestMetaCoin' => [ 'L', 'L', 'L', 'L' ],
'Contract: MetaCoin' => [ 'K', 'K', 'K', 'L' ]
}
I need to write this map in a CSV file that contains my keys like a column name and the values associated with the column titles in the column below them in this way:
How can I write my CSV file?
2 Respostas
Responde à pergunta0
You can create a csv file string and use fs to write to a file like this;
First looping through all the keys to create the header
var myStr = ""
// Creating header
for(let key of map.keys()){
myStr += key+","
}
myStr = myStr.slice(0,-1)+"\r\n";
Getting the first array using map.values()
const [firstValue] = map.values();
Now looping through all the keys and getting a particular element from all the arrays an creating a row for a csv file
// Creating each row
for(let i = 0; i<firstValue.length; i++){
var row = ""
for(let key of map.keys()){
if(map.get(key)[i]){
row += map.get(key)[i]+","
}else{
row += ","
}
}
myStr += row.slice(0, -1)+"\r\n";
}
Saving the string to the csv file
fs.writeFileSync('./mycsv.csv',myStr);
0
The usual convention is that the first line contains the column names/titles, with the remaining lines being the data.
To accomplish that (assuming that your data is contained in a Map or WeakMap), you can do something like this:
function toCSV( map = new Map() ) {
const header = Array.from( map.keys() )
.join(",")
;
const records = Array.from( map.values() )
.map( arr => arr.join(",") )
;
const csv = [
headers,
...records,
].join("\n");
return csv;
}