Module dk.cloudcreate.essentials.shared

Package dk.cloudcreate.essentials.shared.messages

Interface MessageTemplate

All Known Implementing Classes:

MessageTemplate0, MessageTemplate1, MessageTemplate2, MessageTemplate3, MessageTemplate4

public interface MessageTemplate

The MessageTemplate concept supports structured messages with typed parameters.
Each MessageTemplate instance has a unique getKey() that clearly identifies the MessageTemplate.
MessageTemplate keys can be nested, to support message hierarchies:

 // Has key: "ESSENTIALS"
 MessageTemplate0 ROOT = MessageTemplates.root("ESSENTIALS");

 // Has key: "ESSENTIALS.VALIDATION"
 MessageTemplate0 VALIDATION = ROOT.subKey("VALIDATION");

 // Has key: "ESSENTIALS.VALIDATION.AMOUNT_TOO_HIGH"
 MessageTemplate2<BigDecimal, BigDecimal> AMOUNT_TOO_HIGH = VALIDATION.key2("AMOUNT_TOO_HIGH",
                                                                          "Amount {0} is higher than {1}");

 // Has key: "ESSENTIALS.VALIDATION.AMOUNT_TOO_LOW"
 MessageTemplate2<BigDecimal, BigDecimal> AMOUNT_TOO_LOW = VALIDATION.key2("AMOUNT_TOO_LOW",
                                                                         "Amount {0} is lower than {1}");
 

There are multiple MessageTemplate subclasses that support a different number of parameters:

• MessageTemplate0 which supports 0 parameters (mostly used for MessageTemplates.root(String) or nested keys)
• MessageTemplate1 which supports 1 parameter
• MessageTemplate2 which supports 2 parameters
• MessageTemplate3 which supports 3 parameters
• MessageTemplate4 which supports 4 parameters

Example defining a MessageTemplate4's:

 // Has key: "ESSENTIALS"
 MessageTemplate0 ROOT = MessageTemplates.root("ESSENTIALS");

 // Has key: "ESSENTIALS.ACCOUNT_OVERDRAWN"
 MessageTemplate4<String, BigDecimal, BigDecimal, LocalDate> ACCOUNT_OVERDRAWN = ROOT.key4("ACCOUNT_OVERDRAWN",
                                                                                           "Account {0} is overdrawn by ${1}. A fee of ${2} will be debited on the {3}");
 

From a MessageTemplate we can create Message instances, which are useful for e.g. error reporting. A Message is an instance of a MessageTemplate with parameters bound to it.
Example creating a Message from a MessageTemplate4:

 MessageTemplate4<String, BigDecimal, BigDecimal, LocalDate> ACCOUNT_OVERDRAWN = ROOT.key4("ACCOUNT_OVERDRAWN",
                                                                                           "Account {0} is overdrawn by ${1}. A fee of ${2} will be debited on the {3}");

 String accountId = "Account1";
 BigDecimal overdrawnAmount = new BigDecimal("125");
 BigDecimal feeAmount = new BigDecimal("10");
 LocalDate  feeDebitDate =  LocalDate.of(2023, 2, 25);
 Message msg = ACCOUNT_OVERDRAWN.create(accountId,
                                        overdrawnAmount,
                                        feeAmount,
                                        feeDebitDate);

 

will create a Message with Message.getMessage(): "Account Account1 is overdrawn by $125. A fee of $10 will be debited on the 2023-2-25" (date formatting is dependent on the Locale)

See Also:

MessageTemplates, Message

Method Summary

Modifier and Type	Method	Description
String	getDefaultMessage()	The default Message for the given message key E.g.
String	getKey()	The message key for this MessageTemplate.

Method Detail

getKey

String getKey()

The message key for this MessageTemplate. Message key's can be used for multiple purposes:

• A Message key is the identifier for a message or error (e.g. INVENTORY_ITEM.OUT_OF_STOCK)
• A Message key can be used to lookup translations (e.g. in a Resource bundle)

Returns:

the message key for this MessageTemplate

getDefaultMessage

String getDefaultMessage()

The default Message for the given message key
E.g. say the getKey() is SALES.INVENTORY_ITEM.OUT_OF_STOCK and the concrete MessageTemplate is a MessageTemplate1 then a default english message for this key could be: Inventory item {0} is out of Stock, which would be defined as:

 MessageTemplate1<ProductName> INVENTORY_OUT_OF_STOCK = MessageTemplates.key1("INVENTORY_ITEM.OUT_OF_STOCK", "Inventory item {0} is out of Stock");
 

Returns:

the default message for the given message key