Apex Reference Guide

Apex Reference Guide
Release Notes
Apex DML Operations
ApexPages Namespace
AppLauncher Namespace
Approval Namespace
Auth Namespace
Cache Namespace
Canvas Namespace
ApplicationContext Interface
CanvasLifecycleHandler Interface
ContextTypeEnum Enum
EnvironmentContext Interface
RenderContext Interface
Test Class
Canvas Exceptions
ChatterAnswers Namespace
CommerceBuyGrp Namespace
CommerceExtension Namespace
CommerceOrders Namespace
CommercePayments Namespace
CommerceTax Namespace
ComplianceMgmt Namespace
Compression Namespace
ConnectApi Namespace
Context Namespace
Database Namespace
Datacloud Namespace
DataRetrieval Namespace
DataSource Namespace
DataWeave Namespace
Dom Namespace
embeddedai Namespace
EventBus Namespace
ExternalService Namespace
Flow Namespace
Flowtesting Namespace
FormulaEval Namespace
fsccashflow Namespace
Functions Namespace
ise_bots_apex Namespace
industriesNlpSvc
IndustriesDigitalLending Namespace
Invocable Namespace
InvoiceWriteOff Namespace
IsvPartners Namespace
KbManagement Namespace
LxScheduler Namespace
Messaging Namespace
Metadata Namespace
PlaceQuote Namespace
Pref_center Namespace
Process Namespace
QuickAction Namespace
Reports Namespace
RevSignaling Namespace
RevSalesTrxn Namespace
RichMessaging Namespace
Salesforce_Backup Namespace
Schema Namespace
Search Namespace
Sfc Namespace
Sfdc_Checkout Namespace
Sfdc_Enablement Namespace
sfdc_surveys Namespace
Site Namespace
Slack Namespace
Support Namespace
System Namespace
TerritoryMgmt Namespace
TxnSecurity Namespace
UserProvisioning Namespace
VisualEditor Namespace
Wave Namespace
Appendices
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Canvas Exceptions

The Canvas namespace contains exception classes.

All exception classes support built-in methods for returning the error message and exception type. See Exception Class and Built-In Exceptions.

The Canvas namespace contains this exception:

Exception Description
Canvas.CanvasRenderException Use this class in your implementation of Canvas.CanvasLifecycleHandler.onRender(renderContext). To show an error to the user in your onRender() implementation, throw a Canvas.CanvasRenderException, and the canvas framework will render the error message to the user.  This exception will be managed only within the onRender() method.

Example

The following example implementation of onRender() catches a CanvasException that was thrown because a canvas URL was set with a string that exceeded the maximum length. A CanvasRenderException is created and thrown to display the error to the user.
See the Canvas Developer Guide for additional examples that use CanvasRenderException.