Extends: Error

Description

The ApplicationException class defines a base class used to define various application exceptions.

Important points

• Most languages have their own definition of base exception (error) types. However, this class is implemented symmetrically in all languages supported by the PipServices toolkit and allows to create portable implementations and support proper error propagation in microservices calls.
• Error propagation means that when a microservice implemented in one language calls a microservice(s) implemented in a different language(s), errors are returned throught the entire call chain and restored in their original (or close) type.
• Since the number of potential exception types is endless, the PipServices toolkit supports only 12 standard categories of exceptions, which are defined in ErrorCategory. The ApplicationException class acts as a basis for these 12 standard exception types.
• Most exceptions use a free-form message that describes occured errors. However, this may not be sufficient to create meaninful error descriptions. Therefore, the ApplicationException class proposes an extended error definition that has more standard fields:
  • message: human-readable error description
  • category: one of the 12 standard error categories
  • status: numeric HTTP status code for REST invocations
  • code: unique error code, usually defined as “MY_ERROR_CODE”
  • trace_id: unique transaction id used to trace execution through a call chain
  • details: map with error parameters that can help to recreate meaningful error description in other languages
  • stack_trace: stack trace
  • cause: original error that is wrapped by this exception
• The ApplicationException class is not serializable. To pass errors through the wire it must be converted into a ErrorDescription object and then restored on the receiving end into an identical exception type.

Constructors

Creates a new instance of ApplicationException and assigns its values.

public constructor(category: string = null, trace_id: string = null, code: string = null, message: string = null)

• category: string - (optional) standard error category. Default: Unknown
• trace_id: string - (optional) unique transaction id used to trace execution through the call chain.
• code: string - (optional) unique error code. Default: “UNKNOWN”
• message: string - (optional) human-readable description of the error.

Fields

message

Human-readable error description (usually written in English).

public message: string

category

Standard error category.

public category: string

status

HTTP status code associated with this error type.

public status: number = 500

code

Unique error code.

public code: string = ‘UNKNOWN’

details

Map with additional details that can be used to restore error descriptions in other languages.

public details: StringValueMap

trace_id

Unique transaction id used to trace execution through a call chain.

public trace_id: string

stack_trace

Stack trace of the exception.

public stack_trace: string

cause

Original error wrapped by this exception.

public cause: string

Instance methods

getCauseString

Gets the original error wrapped by this exception as a string message.

public getCauseString(): string

• returns: string - original error message.

getStackTraceString

Gets a stack trace where this exception occured.

public getStackTraceString(): string

• returns: string - stack trace as a string.

setCauseString

Sets original error wrapped by this exception as a string message.

public setCauseString(value: string): void

• value: string - original error message.

setStackTraceString

Sets the stack trace where this exception occurred.

public setStackTraceString(value: string): void

• value: string - stack trace as a string

withCause

Sets a original error wrapped by this exception This method returns a reference to this exception to implement the Builder pattern to chain additional calls.

public withCause(cause: Error): ApplicationException

• cause: Error - original error object
• returns: ApplicationException - exception object

withCode

Sets a unique error code.
This method returns a reference to this exception used to implement the Builder pattern to chain additional calls.

public withCode(code: string): ApplicationException

• code: string - unique error code
• returns: ApplicationException - exception object

withTraceId

Sets a trace id which can be used to trace this error through a call chain.
This method returns a reference to this exception to implement the Builder pattern to chain additional calls.

public withTraceId(traceId: string): ApplicationException

• traceId: string - unique transaction id used to trace error through a call chain.
• returns: ApplicationException - exception object

withDetails

Sets a parameter for additional error details. This details can be used to restore error descriptions in other languages.

This method returns a reference to this exception to implement the Builder pattern to chain additional calls.

public withDetails(key: string, value: any): ApplicationException

• key: string - key to the details parameter name
• value: any - value of the details parameter name
• returns: ApplicationException - exception object

withStackTrace

Sets a stack trace for this error.
This method returns a reference to this exception to implement the Builder pattern to chain additional calls

public withStackTrace(stackTrace: string): ApplicationException

• stackTrace: string - stack trace where this error occured.
• returns: ApplicationException - exception object.

withStatus

Sets a HTTP status code which shall be returned by REST calls. This method returns a reference to this exception to implement the Builder pattern to chain additional calls.

public withStatus(status: number): ApplicationException

• status: number - HTTP error code.
• returns: ApplicationException - exception object

wrap

Wraps another exception into an application exception object.

If original exception is of ApplicationException type, it is returned without changes. Otherwise, a new ApplicationException object is created and the original error is set as its cause.

public wrap(cause: any): ApplicationException

• cause: any - original error object
• returns: ApplicationException - original or newly created ApplicationException object.

Static methods

unwrapError

Unwraps an original exception through wrapped exception objects.

Many frameworks like Seneca or restify wrap original exceptions. That may result in propagating less specific errors and can hide causes of the errors.

public static unwrapError(error: any): ApplicationException

• error: any - error object
• returns: ApplicationException - original error object.

wrapError

Wraps another exception into a specified application exception object.

If the original exception is of ApplicationException type, it is returned without changes. Otherwise, the original error is set as a cause for the specified ApplicationException object.

public static wrapError(error: ApplicationException, cause: any): ApplicationException

• error: ApplicationException - ApplicationException object used to wrap the cause.
• cause: any - original error object.
• returns: ApplicationException - original or newly created ApplicationException object.

See also

• ErrorCategory

• ErrorDescription