AssertThat Addition Nullable Value

[gdycus]

The Children property can be null. If it is null this doesn't evaluate properly. I'm not sure but I assume if Adults is 1 and Children is null then Adults + Children = null. Is there a way to handle this scenario?

[AssertThat("(Adults + Children) <= MaxPeople", ErrorMessage = "Cannot exceed {MaxPeople} people")]

[gdycus]

Does anyone have any suggestions? Thanks!

[jwaliszko]

It is one of the null-related traps.

Take a look at the following expression: 1 + NInt where NInt is of Nullable<int> type.

When evaluated by EA parser, it results in null (EA server-side parser follows C# rules in that matter).

Such an expression is then passed to browser. At client-side, there is no separate parser built by EA. Instead, eval() method is used (see implementation outline). The problem is JavaScript follows different rules when computing such an expression. Evaluation results in 1 this time.

As a workaround I propose to be explicit of how you treats nulls. The alternative expression below is supposed to work coherently at both sides:

((Adults == null ? 0 : Adults) + (Children == null ? 0 : Children)) <= MaxPeople

[gdycus]

I'm getting a parser error

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.ComponentModel.DataAnnotations.ValidationException: AssertThatValidator: validation applied to Adults field failed. ---> ExpressiveAnnotations.Analysis.ParseErrorException: Parse error on line 1, column 29: ... ? 0 : Children)) <= MaxPeople ... ^--- Argument types must match.

[AssertThat("(Adults + (Children == null ? 0 : Children)) <= MaxPeople", ErrorMessage = "Cannot exceed {MaxPeople} people")]
public short Adults { get; set; }
[AssertThat("(Adults + (Children == null ? 0 : Children)) <= MaxPeople", ErrorMessage = "Cannot exceed {MaxPeople} people")]
public short? Children { get; set; }
public int MaxPeople { get; set; }

[jwaliszko]

Indeed, implicit types conversion has been missing for operands of conditional operator... The fixed implementation is provided with the changeset fa765b3. Will be shipped within next version.

[gdycus]

How long before the next release? Thanks On Sep 16, 2017, at 6:08 PM, Jarosław Waliszko <notifications@github.com<mailto:notifications@github.com>> wrote: Indeed, implicit types conversion has been missing for operands of conditional operator. The implementation is provided with the changeset fa765b3<fa765b3>. Will be shipped within next version. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub<#172 (comment)>, or mute the thread<https://github.com/notifications/unsubscribe-auth/AIyqOzHmHnUv28Hr-12tpOc-sLe2xS8Uks5sjFT3gaJpZM4PO9Kx>.

[jwaliszko]

Most likely it should be released somewhere this week.

[jwaliszko]

Released with v2.9.6.