group child records by parentid and sum the amount linq C#
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group child records by parentid and sum the amount linq C#
I have a model with three properties
id int get; set:
name varchar get; set:
int fundedamount get;set;
list<child> childlist get; set:
and child like this
int idget;set;
int parentidget;set;
int amountget;set;
I want to group child records by parentid and sum the amount and assign it to parent.fundedamount using linq.
i am trying it like this:
model.ForEach(f => f.childlist.Where(f1 => f1.parentid== f.Id).Sum(f2 => f2.Amount));
but how to assign it to parent.fundedamount? Do I need to use group by?
I have done without linq like this
foreach (var f in model)
foreach (var fi in f.childlist)
if (fi.parentid== f.Id)
f.FundedAmount += (int)fi.Amount;
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please suggest
2 Answers
2
Firstly, I group by childlist by parentId to get a collection of distinct id associated with the sum Amount.
childlist
parentId
id
Amount
Next, for each group in this collection, I update fundedamount corresponding with the GroupId, means Id of the model.
fundedamount
GroupId
Id
model.childlist.GroupBy(x=> x.parentid).Select(group => new
GroupId = group.Id,
SumOfGroup = group.Sum(x => x.Amount)
).ToList()
.ForEach(group => model.First(m => m.Id = group.GroupId).fundedamount = group.SumOfGroup )
Why not make FundedAmount a read-only property, and have it return the sum of the Amount in the ChildList?
public int FundedAmount
get return ChildList?.Sum(c => c.Amount) ?? 0;
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