Linq SUM values error

Question

public async Task<WalletTrans> getCredits(int id) 
{
    var credit = await _context.walletTrans.ToAsyncEnumerable().Where(r => r.Id == id).Sum(s => s.quantity);
    return credit;
}

I have that code above using C#.net core that supposedly returning a summation of a filed in the table.

But I'm having this error.

"Cannot implicitly convert type 'decimal' to 'ProjectName.Models.ModelName' [ProjectName]"

Your method return type is WalletTrans, but you're returning decimal value from Sum() function. Adjust return type as decimal or assign sum value to any decimal property that WalletTrans class has. — Tetsuya Yamamoto
– Tetsuya Yamamoto, Commented Aug 28, 2018 at 3:52
Thanks for the answer. But I still don't get it. Can you give me sample? — Novice
– Novice, Commented Aug 28, 2018 at 3:55

Access Denied · Accepted Answer · 2018-08-28 03:56:37Z

5

a sample as you asked:

public async Task<decimal> getCredits(int id)
{    
    var credit = await _context.walletTrans.ToAsyncEnumerable().Where(r => r.Id == id).Sum(s => s.quantity);   
    return credit;
}

answered Aug 28, 2018 at 3:56

Access Denied

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3 Comments

Novice Over a year ago

how can I return this as a JSon?

Access Denied Over a year ago

do you mean a string in json format or some jobject from newtone library? Yes you can, just return not credit, but new JObject(credit) or whatever.

Access Denied Over a year ago

Take a look at the following SO thread: stackoverflow.com/questions/6201529/…

Novice · Accepted Answer · 2018-08-29 02:41:57Z

0

This will answer my question regarding on how can I return it as a JSON Object

public async Task<object> getCredits(int id){
    dynamic response = new JObject();
    try {
          decimal credit = await _context.walletTrans.ToAsyncEnumerable().Where(r => r.Id == id).Sum(s => s.quantity);
          response.Credit = credit;
          return response;
        } catch (Exception e) {
            response.Error = e;
            return response;
        }
}

Thanks for All your help :D

answered Aug 29, 2018 at 2:41

Novice

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1 Comment

ryzngard Over a year ago

I would avoid dynamic if you can, and just use correct types. public async Task<JObject>… and then to fill in values, response["Credit"] = credit or response["Error"] = e.

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