Tag Archives: Apex

Enum in Apex

Biswajeet   October 20, 2017   No Comments on Enum in Apex

An enum is an abstract data type with values that each take on exactly one of a finite set of identifiers that you specify. Enums are typically used to define a set of possible values.

Although each value corresponds to a distinct integer value, the enum hides this implementation so that you don’t inadvertently misuse the values, such as using them to perform arithmetic. After you create an enum, variables, method arguments, and return types can be declared of that type. Apex provides built-in enums, such as LoggingLevel, and you can define your own enum.

To define an enum, use the enum keyword in your declaration and use curly braces to demarcate the list of possible values.

For Example:
The following code creates an enum called Season:

public enum Season {WINTER, SPRING, SUMMER, FALL}

By creating the enum Season, you have also created a new data type called Season. You can use this new data type as you might any other data type.

For Example:

Season e = Season.WINTER;

Season CheckSeason(Season e) {
    if (e == Season.SUMMER){
		return e;
	}
}

Enum Methods:
All Apex enums, whether user-defined enums or built-in enums, have the following common method that takes no arguments.

values : This method returns the values of the Enum as a list of the same Enum type. Each Enum value has the following methods that take no arguments.
name : Returns the name of the Enum item as a String.
ordinal : Returns the position of the item, as an Integer, in the list of Enum values starting with zero.
Note: Enum values cannot have user-defined methods added to them.
For Example:

Integer i = StatusCode.DELETE_FAILED.ordinal();
String s = StatusCode.DELETE_FAILED.name();
List<StatusCode> values = StatusCode.values();

Lock Records Using Apex in Salesforce

Biswajeet   October 20, 2017   No Comments on Lock Records Using Apex in Salesforce

In Apex, to lock records, simply use the FOR UPDATE keyword in your SOQL statements. While an sObject record is locked, no other client or user is allowed to make updates either through code or the Salesforce user interface. The client locking the records can perform logic on the records and make updates with the guarantee that the locked records won’t be changed by another client during the lock period. The lock gets released when the transaction completes.

Note: FOR UPDATE does not work to lock User object records.

For example, the following statement, in addition to querying for 5 Account record, also locks the accounts that are returned:

List<Account> accList = [SELECT Id, Name From Account LIMIT 5 FOR UPDATE];

Locking Considerations:

  • While the records are locked by a client, the locking client can modify their field values in the database in the same transaction. Other clients have to wait until the transaction completes and the records are no longer locked before being able to update the same records. Other clients can still query the same records while they’re locked.
  • If you attempt to lock a record currently locked by another client, your process waits for the lock to be released before acquiring a new lock. If the lock isn’t released within 10 seconds, you will get a QueryException. Similarly, if you attempt to update a record currently locked by another client and the lock isn’t released within 10 seconds, you will get a DmlException.
  • If a client attempts to modify a locked record, the update operation might succeed if the lock gets released within a short amount of time after the update call was made. In this case, it is possible that the updates will overwrite those made by the locking client if the second client obtained an old copy of the record. To prevent this from happening, the second client must lock the record first. The locking process returns a fresh copy of the record from the database through the SELECT statement. The second client can use this copy to make new updates.

Redirecting Back to Previous Page Using Visualforce Page StandardController

Biswajeet   October 19, 2017   1 Comment on Redirecting Back to Previous Page Using Visualforce Page StandardController

Visualforce Page Button:

<apex:commandButton action="{!back}" value="Back"/>

Apex Controller:

public with sharing class ExampleController
{
    private ApexPages.StandardController sctrl;
    public SaveAndReturnController(ApexPages.StandardController stdController)
    {
        this.sctrl = stdController;
    }
 
    public PageReference back()
    {
        PageReference cancel = sctrl.cancel();
        return cancel;
    }
}