# Copyright 2022 The SQLNet Company GmbH
#
# This file is licensed under the Elastic License 2.0 (ELv2).
# Refer to the LICENSE.txt file in the root of the repository
# for details.
#
"""
Reads a CSV file into the database.
"""
from typing import Any, Dict, List, Optional, Union
import getml.communication as comm
from .connection import Connection
from .helpers import _retrieve_urls
[docs]def read_csv(
name: str,
fnames: Union[str, List[str]],
quotechar: str = '"',
sep: str = ",",
num_lines_read: int = 0,
skip: int = 0,
colnames: Optional[List[str]] = None,
conn: Optional[Connection] = None,
):
"""
Reads a CSV file into the database.
Example:
Let's assume you have two CSV files - *file1.csv* and
*file2.csv* . You can import their data into the database
using the following commands:
>>> stmt = data.database.sniff_csv(
... fnames=["file1.csv", "file2.csv"],
... name="MY_TABLE",
... sep=';'
... )
>>>
>>> getml.database.execute(stmt)
>>>
>>> stmt = data.database.read_csv(
... fnames=["file1.csv", "file2.csv"],
... name="MY_TABLE",
... sep=';'
... )
Args:
name (str):
Name of the table in which the data is to be inserted.
fnames (List[str]):
The list of CSV file names to be read.
quotechar (str, optional):
The character used to wrap strings. Default:`"`
sep (str, optional):
The separator used for separating fields. Default:`,`
num_lines_read (int, optional):
Number of lines read from each file.
Set to 0 to read in the entire file.
skip (int, optional):
Number of lines to skip at the beginning of each
file (Default: 0).
colnames(List[str] or None, optional):
The first line of a CSV file
usually contains the column names. When this is not the case, you need to
explicitly pass them.
conn (:class:`~getml.database.Connection`, optional):
The database connection to be used.
If you don't explicitly pass a connection,
the engine will use the default connection.
"""
# -------------------------------------------
conn = conn or Connection()
# -------------------------------------------
if not isinstance(fnames, list):
fnames = [fnames]
fnames_ = _retrieve_urls(fnames)
# -------------------------------------------
cmd: Dict[str, Any] = {}
cmd["name_"] = name
cmd["type_"] = "Database.read_csv"
cmd["fnames_"] = fnames_
cmd["quotechar_"] = quotechar
cmd["sep_"] = sep
cmd["skip_"] = skip
cmd["num_lines_read_"] = num_lines_read
cmd["conn_id_"] = conn.conn_id
if colnames is not None:
cmd["colnames_"] = colnames
# -------------------------------------------
comm.send(cmd)