My question is if there is a simple way to return a subset of JSON object that will contain all 'columns' rather than specifying individually which 'columns' to return.
In particular, I have a multi-column csv file converted to JSON. The function below returns a subset of that object - just two 'columns' (as another object) if certain condition is met (in this case 'Name' is matched):
var firstSubArr = json.map(function(s) {
if (s.Name === RegName) {
return {
'Price': s.Price,
'Name': s.Name
}
}
}).filter(function(n) {
return n !== undefined
});
Is there a simpler way to return "all columns" from json object as object rather that this:
return {'Price':s.Price,'Name':s.Name}?
Comment: It is just a simple JSON structure after conversion from csv, eg:
`[
{Name:'Sydney', Price:123, Type:'xyz', etc. 20 more... },
etc.
]`
Comment 2: Yes filter may be an option as a couple of people suggested but what if my condition is a bit more plex, like:
var fullPeriodArr= json.map( function (s) {
if(moment(s.Date,"YYYYMMDD").isSameOrBefore(currd) && moment(s.Date,"YYYYMMDD").isSameOrAfter(fullPeriodStart) && (s.Type==sid || s.Type==sid2)&& s.Name===RegName){return [s.Price, s.Name]
}
}).filter( function (n) {
return n!== undefined
});
SOLUTION:
All 3 respondents provided the clue, thanks! It was just “return every object in the array of objects that matches the condition”, or simply:
var firstSubArr= json.filter(
s => (moment(s.Date,"YYYYMMDD").isSameOrBefore(currd) && moment(s.Date,"YYYYMMDD").isSameOrAfter(fullPeriodStart) && (s.Type==sid || s.Type==sid2) && s.Name===RegName)
);
. where time range 'from... to' is evaluated using moment.js lib and Date, Type and Name are object keys.
The secret pudding was the round bracket ( ) around the plex condition.
How neat Javascript has bee: no need to get .length nor to loop with 'for' or 'while', no 'if... else' statements, or no need to store interim results, and no 'return'. The arrow replaces all that!
Then you can access eg. Price 'column' as array of numbers for summary calculations (eg. sum of values):
var firstSubArrPrice=firstSubArr.map(t => t.Price );
My question is if there is a simple way to return a subset of JSON object that will contain all 'columns' rather than specifying individually which 'columns' to return.
In particular, I have a multi-column csv file converted to JSON. The function below returns a subset of that object - just two 'columns' (as another object) if certain condition is met (in this case 'Name' is matched):
var firstSubArr = json.map(function(s) {
if (s.Name === RegName) {
return {
'Price': s.Price,
'Name': s.Name
}
}
}).filter(function(n) {
return n !== undefined
});
Is there a simpler way to return "all columns" from json object as object rather that this:
return {'Price':s.Price,'Name':s.Name}?
Comment: It is just a simple JSON structure after conversion from csv, eg:
`[
{Name:'Sydney', Price:123, Type:'xyz', etc. 20 more... },
etc.
]`
Comment 2: Yes filter may be an option as a couple of people suggested but what if my condition is a bit more plex, like:
var fullPeriodArr= json.map( function (s) {
if(moment(s.Date,"YYYYMMDD").isSameOrBefore(currd) && moment(s.Date,"YYYYMMDD").isSameOrAfter(fullPeriodStart) && (s.Type==sid || s.Type==sid2)&& s.Name===RegName){return [s.Price, s.Name]
}
}).filter( function (n) {
return n!== undefined
});
SOLUTION:
All 3 respondents provided the clue, thanks! It was just “return every object in the array of objects that matches the condition”, or simply:
var firstSubArr= json.filter(
s => (moment(s.Date,"YYYYMMDD").isSameOrBefore(currd) && moment(s.Date,"YYYYMMDD").isSameOrAfter(fullPeriodStart) && (s.Type==sid || s.Type==sid2) && s.Name===RegName)
);
. where time range 'from... to' is evaluated using moment.js lib and Date, Type and Name are object keys.
The secret pudding was the round bracket ( ) around the plex condition.
How neat Javascript has bee: no need to get .length nor to loop with 'for' or 'while', no 'if... else' statements, or no need to store interim results, and no 'return'. The arrow replaces all that!
Then you can access eg. Price 'column' as array of numbers for summary calculations (eg. sum of values):
var firstSubArrPrice=firstSubArr.map(t => t.Price );Share Improve this question edited Apr 11, 2019 at 11:48 edaus asked Apr 10, 2019 at 12:56 edausedaus 1991 gold badge1 silver badge13 bronze badges 2
-
Can you please elaborate a bit more and add tell how
jsonlooks like. – Maheer Ali Commented Apr 10, 2019 at 12:59 - Do you want it to be just pure js? – lankovova Commented Apr 10, 2019 at 13:01
4 Answers
Reset to default 8Get rid of the map() and just use filter() and you will have the original objects in resultant
var firstSubArr = json.filter(function(s) {
return s.Name === RegName
});
I understood that you want to return the the object with specific properties which matches the condition.You can do that using reduce()
var firstSubArr = json.reduce((ac,{Name,Price}) => a.Name === RegName ? [...ac,{Name,Price}] : ac, []);
If you don't want only Name,Price and all properties with calling names. Then use filter() alone
var firstSubArr = json.filter(x => x.Name === RegName)
How about:
var firstSubArr = json.filter( x => x.Name ===RegName)
To make it in JavaScript I remend this code:
var valueNeedly = json.filter(function(s) {
return s.value === searchValue
});