Formatting Dates and Numbers

If you need the user to enter dates or numeric values, you may need to use the user-friendly formatting for these values. The formatting uses the culture in which the HTTP request was processed. See the Globalization.

Formatting Values

The Literal can apply a format string to viewmodel values. If you need to output a date or number value in the page, you can use the following syntax:

<dot:Literal Text="{value: BirthDate}" FormatString="dd/MM/yyyy" />
<dot:Literal Text="{value: TotalPrice}" FormatString="c2" />

DotVVM uses the same format string syntax you know from C# with the following limitations:

• Standard Numeric Format Strings: DotVVM supports d, g, n, c and p format specifiers.

• Custom Numeric Format Strings: DotVVM supports 0, . and # tokens.

• Standard Date and Time Format Strings: DotVVM supports everything except O, U and R format specifiers.

• Custom Date and Time Format Strings: DotVVM supports everything except the K, :, \ and % tokens.

Editing Formatted Values

You can enforce the date or number format in the TextBox control using the FormatString property. To make sure the format string is interpreted correctly, it is strongly recommended to add also the ValueType="Number" or ValueType="DateTime".

<dot:TextBox Text="{value: BirthDate}" ValueType="DateTime" FormatString="d" />
<dot:TextBox Text="{value: TotalPrice}" ValueType="Number" FormatString="n2" />

Validation Numeric and Date Values

If the user enters a value that cannot be parsed, the null value will be stored in the viewmodel property. If the property is of a non-nullable type, it will get the default value on the server (e.g. 0 for int type).

You can use the Required attribute to validate numeric and DateTime values. If the value cannot be parsed, the client-side Required validator reports an error because it sees the null value in the property.

If you need to make the value optional, but it has to be in a correct format in case it is entered, you can use the DotvvmEnforceClientFormat attribute. If the field is empty or the format is correct, the property is valid. But if the value cannot be parsed, the validation reports an error.

// if the field is empty or the value cannot be parsed, this will report an error
[Required]
public int RequiredNumber { get; set; }

// if the value cannot be parsed, this will report an error
// however if the field is empty, the validation succeeds and the property will be null
[DotvvmEnforceClientFormat]
public DateTime? OptionalDate { get; set; }