Decimal data type returns odd, incorrect value about mysqlconnector

[bgrainger]

I would expect your code to work (based on some existing tests) but it's quite possible there's some edge case not being correctly handled yet. Thanks for supplying a concise repro; I'll try to use it to repro the bug you describe soon.

What version of MySQL Server are you running, and on what OS?

[ScottAllSet]

OS: Mac OSX 10.11.6
MySQL 5.7.13 (current GA) running locally
dotnet core 1.0.0-preview2-003121

I will try on MySQL 5.6 shortly.

[ScottAllSet]

I just validated that I'm getting the issue with 5.6.31 as well:
https://dev.mysql.com/downloads/file/?id=463211

[ScottAllSet]

I validated a couple other things just to weed out some possibilities:

1. it happens when I only select the currency column and retrieve it via ordinal 0 (such as your test)
2. it happens when I change the column order to force select * to return it as ordinal 0.

[bgrainger]

I installed MySQL Server 5.7.13 on Mac OS X 10.10.5 but couldn't reproduce with a similar (not exactly the same) test case: 909990c (also passed on Linux).

Are you inserting the row with this connector? Using a literal statement, or using a parameterised insert? Can you verify that the DB does actually contain 85.3 (e.g., with MySQL Workbench)?

It definitely seems consistent with your currency column, but I can't figure out yet what's different.

[bgrainger]

It's not consistent but it's always wrong and always a really big number.

Can you give some more examples of the other bad values you get? There may be some kind of pattern in them that gives a clue to the cause of the bug.

[ScottAllSet]

Here's a screenshot of the commands I ran in MySQL workbench and the output. I haven't tried inserting the row using the connector, only MySQL Workbench.

It appears that the values I get back are all the same for a given run but change each run without me changing or adding anything to the database.
First run:

Second run:

Here's Workbench with the three values:

[bgrainger]

If you change your table creation to currency decimal(13,3) DEFAULT NULL do you start getting larger "random" numbers, e.g., 4534471829.345?

[ScottAllSet]

I don't get larger whole numbers but the mantissa does increase to 3 digits:

[bgrainger]

Is it possible you could share the whole ConsoleApplication.Test solution (e.g., attach a ZIP to this issue)?

[ScottAllSet]

Certainly!
Here's the code I'm using. I also included the SQL.
tester.zip

[ScottAllSet]

Is it possible the use of invariant culture when parsing the decimal is the problem? Mine is en-US, are you using the same? I'm just spit-balling here.

[bgrainger]

Thanks. I can reproduce your problem now, and I think it's a bug in the VS Code debugger.

If I add the following two lines before testItems.Add(t):

var currency = t.currency;
var currencyString = t.currency.ToString();

then I get the following output in the Variables window:

t.currency has the correct value if I store it in another variable, but the property value isn't displayed accurately in VS Code. (Additionally, System.Console.WriteLine(t.currency) also prints the expected value.) This may also explain why the value changes each time but is consistent for one run of the program (if it depends on something in the current debugging session).

[bgrainger]

I can reproduce the problem with one line of code: var t = new Test { id = 1, name = "Sarah", currency = 85.3m };. (All the MySQL-related code can be deleted.)

In the Variables pane in the debugger, t.currency shows the wrong value.

I searched vscode issues for decimal but didn't find anything. You may need to report this as a new issue to the VS Code team.

[bgrainger]

BTW, you can work around the bug by making currency a public field (i.e., public decimal currency;) instead of a property (public decimal currency {get;set;}). This indicates to me that it might be a problem with Code correctly reading the compiler-generated backing field for the property.

Indeed, if we write the property out in full:

public decimal currency
{
    get { return _currency; }
    set { _currency = value; }
}
private decimal _currency;

we get the following Variable output:

[bgrainger]

I've filed this as microsoft/vscode#9929.

[ScottAllSet]

Thank you very much!