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Scout/Concepts/CodeType

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A CodeType is a structure to represent a tree key-code association. They are used in SmartField and SmartColumn.

  • implements: I obj.pngICodeType<T>
  • extends: C obj.pngAbstractCodeType<T>


Description

CodeType are used in SmartField to let the user choose between a finish list of values. The value stored by the field correspond to the key of the selected code.

Scout SmartField Hierarchy SWT.png

A CodeType can be seen as a tree of Codes. Each code associate to the key (the Id) other properties: among others a Text and an IconId.

In order to have the same resolving mechanism (getting the display text of a key) CodeType are also used in SmartColumn. To chose multiple value of the list, the fields ListBox (flat CodeType) and TreeBox (hierarchical CodeType) can be used.


Organisation of the codes

The codes are organized in a tree. Therefore a CodeType can have one or more child codes at the root level, and each code can have other child codes. In lot of cases a list of codes (meaning a tree containing only leafs at the first level) is sufficient to cover most of the need.

Child codes are ordered in their parent code. This is realized with the order annotation.


Type of the key

The type of the key is defined by its generic parameter <T>. It is very common to use a type from the java.lang.* package (like Integer or String) but any Java Object is suitable. It must:

  • implements Serializable
  • have correctly implemented equals() and hashCode() functions
  • present in the server and the client

There is no obligation to have the same type for the Id between the codes of a CodeType (meaning the same generic type parameter for the codes inner-class). However it is a good practice to have the same type between the codes of a CodeType, because the Id are used as value of SmartFields. Therefore the generic parameter describing the type of value of a SmartField must be compatible with the type of the codes contained in the CodeType.


Using a CodeType

SmartField or SmartColumn

CodeType in a SmartField (or SmartColumn).

public class YesOrNoSmartField extends AbstractSmartField<Boolean> {
  // other configuration of properties.
  @Override
  protected Class<? extends ICodeType<?>> getConfiguredCodeType(){
    return YesOrNoCodeType.class;
  }
}

If the SmartField (or SmartColumn) works with a CodeType, a specific LookupCall is instantiated to get the LookupRows based on the Codes contained in a CodeType.

Accessing a code directly

Scout-runtime will handle the instantiation and the caching of CodeTypes.

This function returns the text corresponding to the key using a CodeType:

  public String getColorName(String key){
    ICode c = CODES.getCodeType(ColorCodeType.class).getCode(key);
    if(c != null) {
      return c.getText();
    }
    return null;
  }
}


Static CodeType

Java Code and structure

Scout CodeType Structure.png

The common way to define a CodeType is to extend AbstractCodeType. Each code is an inner-class extending AbstractCode. Like usual the properties of Codes and CodeTypes can be set with getConfiguredXxxxxx() methods.

See the Java Code of a simple YesOrNoCodeType having just two codes:

  • YesOrNoCodeType.YesCode
  • YesOrNoCodeType.NoCode


With the SDK

The SDK provides some help to generate CodeTypes and Codes. The CodeType appears in the Explorer View in the Enumerations folder under shared.

ScoutSDK CodeType.png

It is possible to add a new CodeType using a wizard.


Dynamic CodeType

Code types are not necessary hardcoded. It is possible to implement other mechanisms to load CodeType dynamically.

The description of the Codes can come from a database or from an XML files. If you want to do so, you just need to implement the method corresponding to the event LoadCodes.

Note.png
TODO
Describe good organization of classes to load codeType from an XML File or a Database. With small UML graph


It is possible to use the static and the dynamic approach together. In this case, if there is a conflict (2 codes for the same id) the event OverwriteCode is triggered.


Note for advanced users:

Each CodeType is instantiated for

  • each language
  • each partition

Note: A drawback that the CodeType Class is not aware of the language and the partition it is instantiate for. Only the C obj.pngCodeTypeStore that manage the CodeType instances knows for which language and which partition they have been instantiated.


See Also