ConnectionException Class

Assembly: CodeEffects.Rule.Connection.dll
Namespace: CodeEffects.Rule.Connection

Summary

Represents a failure of a statement that a Code Effects library ran against rule storage. Its message says in plain words what was being done and is safe to show. The database's own error is the inner exception.

Syntax

public class ConnectionException : CodeEffects.Rule.Common.RuleException

Inheritance

• System.Object
  • System.Exception
    • CodeEffects.Rule.Common.RuleException
      • CodeEffects.Rule.Connection.ConnectionException

Remarks

The libraries throw this exception when a statement against the database fails, for example "Could not read the repository's settings." Log the exception, including its InnerException, on the server. The inner exception holds the error of your database, which can name tables, columns, and servers: keep it out of anything a browser receives. The Message and the ControlNumber inherited from RuleException are safe to show.

Where you see it depends on the call. Methods that return a result directly, such as Context.GetAliasNames(..), Context.GetRules(..), and AuditRecorder.GetRules(..), can throw it. A connection that cannot be opened reaches you as the exception of your ADO.NET provider, because the libraries open it outside the statement. Context.GetResponse(..) catches every failure and throws a RepositoryException instead, whose control number and safe message come from the same classification, and whose ResponseJson you can return to the client. Context.SyncSources(..) reports a failed definition in its SourceResult and then throws a RepositoryException.

The control number tells the cause apart:

Control number	Constant	Cause
CE19002	DatabaseError	A database error that is not a timeout. This is the default.
CE19003	DatabaseTimeout	The database did not respond in time.
CE19004	SchemaBehind	A table or column is missing because the database is behind the library. The message names the update scripts to run. See SchemaCheckResult.

The classification of an error as a timeout or as a missing object comes from the IDialect of your provider through Classify(..), which returns a DbFailureKind.

Fields

Properties

Example

using System;
using CodeEffects.Rule.Connection;
using CodeEffects.Rule.Repository;

try
{
	var aliases = Context.GetAliasNames(dbProvider);
}
catch(ConnectionException ex) when(ex.ControlNumber == ConnectionException.SchemaBehind)
{
	// Safe to show: it names the update scripts to run
	Console.WriteLine(ex.Message);
}
catch(ConnectionException ex)
{
	// Log the database's own error on the server only
	Console.WriteLine($"{ex.ControlNumber}: {ex.Message}");
	Console.WriteLine(ex.InnerException);
}