[英]In a PostgreSQL CHECK constraint using a boolean stored procedure written in PL/Python, can the detail of the error message be updated?
The qustion's in the (albeit long) title. qustion在(尽管很长)的标题中。 I have code in this fashion:
我有这样的代码:
-- create the tables for models
CREATE TABLE invoice(
id SERIAL PRIMARY KEY,
value VARCHAR(8)
CONSTRAINT valid_money CHECK(validate_invoice_money(value))
);
with this procedure: 用这个程序:
CREATE OR REPLACE FUNCTION validate_invoice_money(test VARCHAR) RETURNS BOOLEAN AS $$
import plpy
import re
if (re.match("^[0-9]+\\.[0-9]{2}$", test) == None):
return False
return True
$$ LANGUAGE plpython3u IMMUTABLE;
(the specifics of this example are not important, I know there's better ways to validate a value than this, such as using the MONEY
type.) (这个例子的细节并不重要,我知道有更好的方法来验证一个值,比如使用
MONEY
类型。)
When an insert is attempted that fails this check, I get the following error: 当尝试插入未通过此检查时,我收到以下错误:
ERROR : new row for relation "invoice" violates check constraint "valid_model"
DETAIL : Failing row contains (1, "notvalid").
(the error/detail descriptors are my own code, but a PostgreSQL error has an error and a detail field provided.) (错误/详细描述符是我自己的代码,但PostgreSQL错误有错误,并提供详细信息字段。)
Is there any way for me to change the "detail" portion of this error from my Python procedure? 有没有办法让我从Python程序中更改此错误的“详细信息”部分?
In Postgres 9.6+ you can raise an error with detailed messages from a plpython function using utility functions, eg: 在Postgres 9.6+中,您可以使用实用程序函数从plpython函数中提取详细消息,例如:
CREATE OR REPLACE FUNCTION validate_invoice_money(test VARCHAR)
RETURNS BOOLEAN AS $$
import re
if (re.match("^[0-9]+\\.[0-9]{2}$", test) == None):
plpy.error("custom exception message",
detail="some info about exception",
hint="hint for users")
return False
return True
$$ LANGUAGE plpython3u IMMUTABLE;
insert into invoice
values (default, 'notvalid');
ERROR: plpy.Error: custom exception message
DETAIL: some info about exception
HINT: hint for users
CONTEXT: Traceback (most recent call last):
PL/Python function "validate_invoice_money", line 8, in <module>
hint="hint for users")
PL/Python function "validate_invoice_money"
You don't need an additional language; 你不需要额外的语言; you can use a plain regexp for the value constraint:
你可以使用普通正则表达式来限制值:
-- create the tables for models
CREATE TABLE invoice(
id SERIAL PRIMARY KEY,
val VARCHAR(8)
-- CONSTRAINT valid_money CHECK(validate_invoice_money(value))
CONSTRAINT valid_money CHECK(val ~ '^[0-9]+\.[0-9]{2}$' )
);
INSERT INTO invoice (val) VALUES ('0123.98' ); -- success
INSERT INTO invoice (val) VALUES ('a123.98' ); -- failure
SELECT * FROM invoice;
Result: 结果:
CREATE TABLE
INSERT 0 1
ERROR: new row for relation "invoice" violates check constraint "valid_money"
DETAIL: Failing row contains (2, a123.98).
id | val
----+---------
1 | 0123.98
(1 row)
And to answer the question: I do not think you can get additional info on the constraint violation. 并回答这个问题:我认为您无法获得有关约束违规的其他信息。
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