title: Possible to use pandas/sqlalchemy to insert arrays into sql database? (postgres)
body: <p>With the following:</p>
  
  <pre><code>engine = sqlalchemy.create_engine(url)
  
  df = pd.DataFrame({
      "eid": [1,2],
      "f_i": [123, 1231],
      "f_i_arr": [[123], [0]],
      "f_53": ["2013/12/1","2013/12/1",],
      "f_53a": [["2013/12/1"], ["2013/12/1"],],
  })
  
  with engine.connect() as con:
      con.execute("""
          DROP TABLE IF EXISTS public.test;
          CREATE TABLE public.test
          (
            eid integer NOT NULL,
            f_i INTEGER NULL,
            f_i_arr INTEGER NULL,
            f_53 DATE NULL,
            f_53a DATE[] NULL,
             PRIMARY KEY(eid)
          );;
          """)
      df.to_sql("test", con, if_exists='append')
  </code></pre>
  
  <p>If I try to insert only column "f_53" (an <code>date</code>) it succeeds.</p>
  
  <p>If I try to add column "f_53a" (a <code>date[]</code>) it fails with:</p>
  
  <pre><code>                                            ^
  sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) column "f_53a" is of type date[] but expression is of type text[]
  LINE 1: ..._53, f_53a, f_i, f_i_arr) VALUES (1, '2013/12/1', ARRAY['201...
                                                               ^
  HINT:  You will need to rewrite or cast the expression.
   [SQL: 'INSERT INTO test (eid, f_53, f_53a, f_i, f_i_arr) VALUES (%(eid)s, %(f_53)s, %(f_53a)s, %(f_i)s, %(f_i_arr)s)'] [parameters: ({'f_53': '2013/12/1', 'f_53a': ['2013/12/1', '2013/12/1'], 'f_i_arr': [123], 'eid': 1, 'f_i': 123}, {'f_53': '2013/12/1', 'f_53a': ['2013/12/1', '2013/12/1'], 'f_i_arr': [0], 'eid': 2, 'f_i': 1231})]
  </code></pre>