Null Type can't be converted to Array

I have ibis version ‘v0.8.1’ and I ran the following,

In [1]: import ibis

In [2]: t = ibis.table(ibis.schema([('a','string')]))

In [3]: t.mutate(b=ibis.null()).columns
Out[3]: ['a', 'b']

In [4]: t.mutate(b=ibis.null())['b']


AttributeError: module 'ibis.expr.types' has no attribute 'NullArray'

I can’t select NullArray by column name. Is this expected?

[cpcloud]

@napjon Added tests in the PR. To do what you’re talking about using your t1 and t2, here’s how you would do it:

In [1]: import ibis

In [2]: t1 = ibis.table(ibis.schema([('a','string'),('b','string')]))

In [3]: t2 = ibis.table(ibis.schema([('a','string')]))

In [4]: mutated = t2.mutate(b=ibis.NA.cast('string'))

In [5]: union = t1.union(mutated)

[napjon]

Got it, thanks @cpcloud!