psycopg2: can't adapt type 'numpy.int64'

问题

I have a dataframe with the dtypes shown below and I want to insert the dataframe into a postgres DB but it fails due to error can't adapt type 'numpy.int64'

id_code               int64
sector              object
created_date         float64
updated_date    float64

How can I convert these types to native python types such as from int64 (which is essentially 'numpy.int64') to a classic int that would then be acceptable to postgres via the psycopg2 client.

data['id_code'].astype(np.int)  defaults to int64

It is nonetheless possible to convert from one numpy type to another (e.g from int to float)

data['id_code'].astype(float)

changes to

dtype: float64

The bottomline is that psycopg2 doesn't seem to understand numpy datatypes if any one has ideas how to convert them to classic types that would be helpful.

Updated: Insertion to DB

def insert_many():
    """Add data to the table."""
    sql_query = """INSERT INTO classification(
                id_code, sector, created_date, updated_date)
                VALUES (%s, %s, %s, %s);"""
    data = pd.read_excel(fh, sheet_name=sheetname)
    data_list = list(data.to_records())

    conn = None
    try:
        conn = psycopg2.connect(db)
        cur = conn.cursor()
        cur.executemany(sql_query, data_list)
        conn.commit()
        cur.close()
    except(Exception, psycopg2.DatabaseError) as error:
        print(error)
    finally:
        if conn is not None:
            conn.close()

回答1:

I'm not sure why your data_list contains NumPy data types, but the same thing happens to me when I run your code. Here is an alternative way to construct data_list that so that integers and floats end up as their native python types:

data_list = [list(row) for row in data.itertuples(index=False)]

Alternate approach

I think you could accomplish the same thing in fewer lines of code by using pandas to_sql:

import sqlalchemy
import pandas as pd
data = pd.read_excel(fh, sheet_name=sheetname)
engine = sqlalchemy.create_engine("postgresql://username@hostname/dbname")
data.to_sql(engine, 'classification', if_exists='append', index=False)

回答2:

same problem here, successfully solve this problem after I transform series to nd.array and int.

you can try as following:

data['id_code'].values.astype(int)

update:

if the value including NaN, it still wrong. It seems that psycopg2 can't explain the np.int64 format, therefore the following methods works for me.

import numpy as np
from psycopg2.extensions import register_adapter, AsIs
psycopg2.extensions.register_adapter(np.int64, psycopg2._psycopg.AsIs)

回答3:

Add below somewhere in your code:

import numpy
from psycopg2.extensions import register_adapter, AsIs
def addapt_numpy_float64(numpy_float64):
    return AsIs(numpy_float64)
def addapt_numpy_int64(numpy_int64):
    return AsIs(numpy_int64)
register_adapter(numpy.float64, addapt_numpy_float64)
register_adapter(numpy.int64, addapt_numpy_int64)

来源：https://stackoverflow.com/questions/50626058/psycopg2-cant-adapt-type-numpy-int64

标签

numpy

psycopg2