How to aggregate with group? about go-linq

[pradeepkusingh]

thank you @cleitonmarx

[cleitonmarx]

Hi @pradeepkusingh,

Follow below an example of how to use the GroupBy function based in your description:

var errors [20]error
var idx int = 0
for idx < 14 {
    errors[idx] = io.ErrShortWrite
    idx++
}
for idx < 20 {
    errors[idx] = io.ErrUnexpectedEOF
    idx++
}

type ErrorReport struct {
    ErrorMessage string
    Counter      int
}

var results []ErrorReport

linq.From(errors).GroupBy(
    func(i interface{}) interface{} { return i.(error).Error() },
    func(i interface{}) interface{} { return i.(error) },
).Select(func(i interface{}) interface{} {
    return ErrorReport{
        ErrorMessage: i.(linq.Group).Key.(string),
        Counter:      len(i.(linq.Group).Group),
    }
}).ToSlice(&results)

for _, r := range results {
    fmt.Printf("Error Message: %s -> Count: %d \n", r.ErrorMessage, r.Counter)
}

Output:

Error Message: short write -> Count: 14 
Error Message: unexpected EOF -> Count: 6