Dissect and kv filter

[Necus]

Hi,
I'm using dissect filter to quickly parse data. Then i would like to use kv to divide one of the newly created field into many values.

new field:
field1=value1,field2=value2,field3=[abc, abc2, abc3],field4=value4

dissect
field1=%{field1},field2=%{field2},field3=%{field3},field4=%{field4}

Dissect works fine (i'm filtering out "[" and "]", but how can I create appriopriate kv filter?

This does not appear to work:
kv {
source => "field3"
field_split => ", "
}

[Badger]

field3 appears to be csv, not kv.

[Necus]

Ok,
Still something is wrong

if:
csv {
source => "field3"
separator => ", "
}
Error parsing csv {:field=>"field3", :source=>"", :exception=>#<NoMethodError: undefined method `each_index' for nil:NilClass>}

Update:
After changing ", " to "," it works (9 out of 10 times, rest error :exception=>#<NoMethodError: undefined method `each_index' for nil:NilClass), but instead of putting multiple value into role field it creates new fields "columns". Target => "role" does not work.

[Badger]

Not sure what to say. With

dissect { mapping => { "message" => "field1=%{field1},field2=%{field2},field3=[%{field3}],field4=%{field4}" } }
csv { source => "field3" separator => ", " target => "role" }

I get

      "role" => {
    "column2" => "abc2",
    "column1" => "abc",
    "column3" => "abc3"
},

[Necus]

And how to change to this:
csv {
source => "field3"
separator => ", "
target => "field3"
}
I do not want any new columns fields, I only want one "field3" multivalue field

[Badger]

If you want field3 to be an array get rid of the csv filter and use

mutate { split => { "field3" => ", " } }

which gets you

    "field3" => [
    [0] "abc",
    [1] "abc2",
    [2] "abc3"
],

[Necus]

Thank you