Python 如何修复错误：（psycopg2.errors.NotNullViolation）列“中的null值；id"；违反非空约束？

为什么会出现下面的错误？我知道

db.session.add（）

方法，但是为了学习，我想使用原始SQL。UUID不应该自动生成吗？可能我在postgresql文本中遗漏了什么，或者模型中的id不正确

错误

Error: (psycopg2.errors.NotNullViolation) null value in column "id" violates not-null constraint
DETAIL:  Failing row contains (null, testuser, email@test.com, pASsWorD, null, 2021-01-10 16:13:23.270353-08).

型号.py

from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy import DateTime
from sqlalchemy.sql import func

from .. import db

class Users(db.Model):
    __tablename__ = 'users'

    id = db.Column(
        UUID(as_uuid=True),
        primary_key=True,
        unique=True,
    )
    username = db.Column(
        db.String(120),
        unique=True,
        nullable=False
    )
    email = db.Column(
        db.String(120),
        unique=True,
        nullable=False
    )
    password = db.Column(
        db.String(120),
        nullable=False
    )
    updated_at = db.Column(
        DateTime(timezone=True),
        onupdate=func.now()
    )
    created_at = db.Column(
        DateTime(timezone=True),
        server_default=func.now()
    )

from flask import Blueprint, request, jsonify
from sqlalchemy import text, exc
from types import SimpleNamespace
from ...models.users import db, Users

bp = Blueprint('api', __name__, url_prefix='/api/v1')

@bp.route('/users', methods=['POST'])
def users():
    if request.method == 'POST':
        try:
            response = dict(request.get_json())
            values = SimpleNamespace(**response)

            if all(response.values()):
                sql_insert_one = text(f"INSERT INTO users(username, email, password) VALUES ('{values.username}', '{values.email}', '{values.password}');")
                db.session.execute(sql_insert_one)
                db.session.commit()
                message = f"successfully added new user: {values.username}"
            else:
                message = f"error adding new user, values submitted: {values}"

            return jsonify(response)
        except Exception as err:
            print(f'Error: {err}') 
            return jsonify(f'"error":"{err}"')

api.py

from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy import DateTime
from sqlalchemy.sql import func

from .. import db

class Users(db.Model):
    __tablename__ = 'users'

    id = db.Column(
        UUID(as_uuid=True),
        primary_key=True,
        unique=True,
    )
    username = db.Column(
        db.String(120),
        unique=True,
        nullable=False
    )
    email = db.Column(
        db.String(120),
        unique=True,
        nullable=False
    )
    password = db.Column(
        db.String(120),
        nullable=False
    )
    updated_at = db.Column(
        DateTime(timezone=True),
        onupdate=func.now()
    )
    created_at = db.Column(
        DateTime(timezone=True),
        server_default=func.now()
    )

from flask import Blueprint, request, jsonify
from sqlalchemy import text, exc
from types import SimpleNamespace
from ...models.users import db, Users

bp = Blueprint('api', __name__, url_prefix='/api/v1')

@bp.route('/users', methods=['POST'])
def users():
    if request.method == 'POST':
        try:
            response = dict(request.get_json())
            values = SimpleNamespace(**response)

            if all(response.values()):
                sql_insert_one = text(f"INSERT INTO users(username, email, password) VALUES ('{values.username}', '{values.email}', '{values.password}');")
                db.session.execute(sql_insert_one)
                db.session.commit()
                message = f"successfully added new user: {values.username}"
            else:
                message = f"error adding new user, values submitted: {values}"

            return jsonify(response)
        except Exception as err:
            print(f'Error: {err}') 
            return jsonify(f'"error":"{err}"')

回答您的问题“UUID不应该自动生成吗？”否。来自postgresql文档：“核心数据库不包含任何生成UUID的函数”

您需要自己生成UUID，请尝试

或者您可以使用

db.Integer

而不是

db.UUID

，SQLAlchemy将使其成为一个序列，并自动生成

id

值。

sql\u insert\u one=text（f“插入用户（id、用户名、电子邮件、密码）值（{UUID.uuid4（）.hex}）、{VALUES.username}、{VALUES.email}、{VALUES.password}”）

工作正常，感谢您的帮助。