go-redis slice result conversion functions in Cmd are broken

slice result conversion functions in Cmd are broken

Open ideasculptor opened this issue 3 years ago • 2 comments

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if one executes a command via client.Do() which will return a Slice, the built-in slice helper methods (StringSlince, Int64Slice, BoolSlice, etc) methods of Cmd do not work as expected. Because each of those methods first calls Slice() and Slice() selects on val.(type) matching []interface{} or else throwing an error, any command more strongly typed than SliceCmd (which expects a slice of interface{}) will throw an exception when using the conversion helper methods, since []int64, []string, etc do not satisfy []interface{}. You have to explicitly create a slice of interface{} to match that type. The net result is that it is possible to call cmd.Val() or cmd.Result() and then cast the returned val to []int64 or []string, but you cannot call cmd.Int64Slice() or cmd.StringSlice() to have the conversion done for you - which is the whole point of the helper methods, I think.

Expected Behavior

cmd := rdb.Do(ctx, "Keys", pattern)
values, err := cmd.StringSlice()

should result in values being populated with the returned values of the command and err being nil

Current Behavior

Instead, err receives a value expressing that unexpected type=[]string is not []interface{}

Possible Solution

remove the call to Slice() within the various Slice() helper methods in Cmd. In the meantime, the issue can be worked around by always calling cmd.Val() and then casting the interface{} returned by that method to the expected type.