id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,pull_request,body,repo,type,active_lock_reason,performed_via_github_app,reactions,draft,state_reason
1128466114,I_kwDOCGYnMM5DQwbC,406,Creating tables with custom datatypes,82988,open,0,,,5,2022-02-09T12:16:31Z,2022-09-15T18:13:50Z,,NONE,,"Via https://stackoverflow.com/a/18622264/454773 I note the ability to register custom handlers for novel datatypes that can map into and out of things like sqlite `BLOB`s.

From a quick look and a quick play, I didn't spot a way to do this in `sqlite_utils`?

For example:

```python
# Via https://stackoverflow.com/a/18622264/454773
import sqlite3
import numpy as np
import io

def adapt_array(arr):
    """"""
    http://stackoverflow.com/a/31312102/190597 (SoulNibbler)
    """"""
    out = io.BytesIO()
    np.save(out, arr)
    out.seek(0)
    return sqlite3.Binary(out.read())

def convert_array(text):
    out = io.BytesIO(text)
    out.seek(0)
    return np.load(out)


# Converts np.array to TEXT when inserting
sqlite3.register_adapter(np.ndarray, adapt_array)

# Converts TEXT to np.array when selecting
sqlite3.register_converter(""array"", convert_array)
```

```python
from sqlite_utils import Database
db = Database('test.db')

# Reset the database connection to used the parsed datatype
# sqlite_utils doesn't seem to support eg:
#  Database('test.db', detect_types=sqlite3.PARSE_DECLTYPES)
db.conn = sqlite3.connect(db_name, detect_types=sqlite3.PARSE_DECLTYPES)

# Create a table the old fashioned way
# but using the new custom data type
vector_table_create = """"""
CREATE TABLE dummy 
    (title TEXT, vector array );
""""""

cur = db.conn.cursor()
cur.execute(vector_table_create)


# sqlite_utils doesn't appear to support custom types (yet?!)
# The following errors on the ""array"" datatype
""""""
db[""dummy""].create({
    ""title"": str,
    ""vector"": ""array"",
})
""""""
```

We can then add / retrieve records from the database where the datatype of the `vector` field is a custom registered `array` type (which is to say, a `numpy` array):

```python
import numpy as np

db[""dummy""].insert({'title':""test1"", 'vector':np.array([1,2,3])})

for row in db.query(""SELECT * FROM dummy""):
    print(row['title'], row['vector'], type(row['vector']))

""""""
test1 [1 2 3] <class 'numpy.ndarray'>
""""""
```

It would be handy to be able to do this idiomatically in `sqlite_utils`.",140912432,issue,,,"{""url"": ""https://api.github.com/repos/simonw/sqlite-utils/issues/406/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,