4.2.2.3. Datatype

Datatype interface describes a valid data type for the entity attribute if it is not a reference. Each Datatype implementation corresponds to a single Java class.

All of the instances are registered in repository – Datatypes class, which performs loading and initializing of Datatype implementation classes in the following way:

  • datatypes.xml file is searched in CLASSPATH root, and if it is found, Datatypes repository is initialized from it.

  • otherwise Datatypes repository is initialized from /com/haulmont/chile/core/datatypes/datatypes.xml file.

Datatype instance can be obtained in two ways:

  • For an entity attribute – from the corresponding meta-property using getRange().asDatatype() call.

  • Using Datatypes.get() static method by passing to it the name of the Datatype implementation or Java class it was created for.

Datatypes are associated with entity attributes during application start according to the following rules:

  • If @MetaProperty annotation is defined on the field or method having a non-empty datatype value, the attribute is associated with the Datatype instance with the given name.

    For instance, if the entity attribute is declared as in the example below, it will be associated with a nonstandard type – GeoCoordinateDatatype:

    @MetaProperty(datatype = GeoCoordinateDatatype.NAME)
@Column(name = "LATITUDE")
private Double latitude;

  • In most cases, explicit specification is omitted, and the attribute is associated with the Datatype instance from repository, which is returned by Datatypes.get(Class) by supplied field or method type.

    In example below, latitude attribute will get a standard DoubleDatatype type registered in the /com/haulmont/chile/core/datatypes/datatypes.xml base file:

    @Column(name = "LATITUDE")
private Double latitude;

Basic methods of Datatype interfaces:

  • getName() – returns the unique name of the implementation.

  • format() – converts the passed value into a string.

  • parse() – transforms a string into the value of corresponding type.

Datatype determines two sets of methods for formatting and parsing: considering and not considering locale. Conversion considering locale is applied everywhere in user interface, ignoring locale – in system mechanisms, for example, serialization in REST API.

Parsing formats ignoring locale are specified in the above mentioned datatypes.xml file.

The parsing formats considering locale are provided in the main localized messages pack, in the strings containing the following keys:

  • numberDecimalSeparator – specifies decimal separator for numeric types.

  • numberGroupingSeparator – defines separator between digits groups for numeric types (e.g. when space is used as separator, number will be formatted as 1 000 000).

  • integerFormat – format for Integer and Long types.

  • doubleFormat – format for Double type.

  • decimalFormat – format for `BigDecimal `type.

  • dateTimeFormat – format for java.util.Date type.

  • dateFormat – format for java.sql.Date type.

  • timeFormat – format for java.sql.Time type.

  • trueString – string corresponding to Boolean.TRUE.

  • falseString – string corresponding to Boolean.FALSE.

All the listed formats are specified in the main localized message pack of CUBA base projects by default, and can be overridden in the similar files of the application project.