omit type of array in a function argument with golang

Question

I'm writing a write method, to write an array of value to InfluxDB

What I would like is to be able to have something like:

func (influxClient *InfluxClient) Write(myArray []interface{}) (error) {
    fmt.Print(myArray)
    // Insert into DB
    return nil

}

Where myArray could be an array with any objects inside

I tried to use myArray []interface{} to ommit myArray's type, but it doesn't work, I get:

Cannot use 'meters' (type []models.Meter) as type []interface{}

Is it possible to achieve it ?

How should I do ?

if you try to formating a slice of something to a slice of interface, you should maybe have a look [here](https://stackoverflow.com/questions/12753805/type-converting-slices-of-interfaces-in-go) — charles Lgn, Jun 26 '19 at 08:51

score 1 · Accepted Answer · answered Jun 26 '19 at 09:12

1

This happens because []models.Meter and []interface{} are two different types for the Go compiler.

Using interface{} is not a best-practice typically. It would be better to define your own type and use that instead.

Having said that, the quickest solution for your case should be to make Write function a variadic one. Like the example below.

https://play.golang.org/p/KzzFMAjQvRa

func Write(myArray ...interface{}) (error) {
    fmt.Printf("Slice: %v\n", myArray)
    // Insert into DB
    return nil

}

answered Jun 26 '19 at 09:12

Giulio Micheloni

1,290
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Yes, thing is I would have a single array of "objects", so ... it might not be the best fit – Juliatzin Jun 26 '19 at 09:29
Are you saying that the slice of objects is already built before calling `Write` method? In that case you just need to invoke it like this: `Write(mySlice...)`. – Giulio Micheloni Jun 26 '19 at 09:35
Yep, my input in a slice of objects. Objects type may vary. I will check if that works – Juliatzin Jun 26 '19 at 10:01

score 0 · Answer 2 · answered Jun 26 '19 at 10:18

It is possible if you copy first to an []interface instance

func main() {

   // Copy from your explicit type array
   var interfaceSlice []interface{} = make([]interface{}, len(models.Meter))

   for i, Modelvalue := range models.Meter {
       interfaceSlice[i] = Modelvalue
   }    

   influxClient.Write(interfaceSlice)
}

Wiki Interface slice and arrays

Playground sample

omit type of array in a function argument with golang

2 Answers2