[GitHub] [arrow] zeroshade commented on issue #10972: [Go] Is there a way to get the value at a given index from an Interface

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zeroshade commented on issue #10972:
URL: https://github.com/apache/arrow/issues/10972#issuecomment-905161847


   Hey @bidhan-a in order to get the actual value at a given index you need to cast the Interface to the correct type which will provide the type-safe access methods. One example would be to do a type-switch on the actual `Interface` type such as in the integration testing code here: https://github.com/apache/arrow/blob/master/go/arrow/internal/arrjson/arrjson.go#L925
   
   Alternately you could switch on the type id:
   
   ```go
   func val(col array.Interface, idx int) interface{} {
       switch col.DataType().ID() {
       case arrow.INT32:
           return col.(*array.Int32).Value(idx)
       case arrow.STRING:
           return col.(*array.String).Value(idx)
       // and so on.....
   }
   ```
   
   Either way, in order to get the value at a given index, you need to know which underlying array type you actually have, and all of the types have accessors to retrieve the values at indexes once you've type-asserted them to the proper type.
   
   Hope that helps!


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