Apex-Commandments

• Curated list of Apex Best Practices from TrialheadDX 2017
• CREDITS : Apex 10 Commandments - https://www.youtube.com/watch?v=yqJZDmW1yLI

Apex Best Practices

Rule 1: Don't use SOQL queries inside For-Loops

• Queries in For Loops can break governer limits
• Total Query limit per execution context is 100.

• Take SOQL queries out of For-Loop. Here in this case, we are using relationship queries.

Rule 2: Don't use DML Operations inside For-Loops

• Using DML Operations inside for loops can break governer limits.
• DML Operation Limit per execution context is 150.

 

• Add the instance variable to a list and then perform DML operation outside of For-loop

 

Rule 3: Define only 1 trigger per Object

• This is because, if we have multiple triggers per Object, salesforce does not guarentee the order of execution.

Rule 4: Don't add code directly to Triggers other than reference to other classes or methods

• As best practice, always create an Handler Classes

Rule 5: Use Maps for Queries whenever possible

• By using Map, we can always retrieve a specific record using ID.

Rule 6: Use Relationships in SOQL to reduce Queries

• Parent-child and Child-Parent Relationships in Salesforce are useful to reduce number of Queries, so that the risk of breaking governer limits are reduced

• When we go from Child-Parent, we can go upto 5 levels up in the hierarchy.

• When we go from Parent-Child, it is limited to 1 level down.

Rule 7: Aim for 100% Test Coverage

• Atleast 3 scenarios should be tested:

  • Positive Test Case
  • Negative Test Case
  • User/Profile/Role based Case

• Example of a Positive Test Case

• Example of a Negative Test Case
• We are forcing an error and we are checking the error which was thrown was the error which we are expecting.

 

• Example of User/Role/Profile based Test Case
• Use System.runAs() method for this type of test cases.

Rule 8: Write Useful Test Cases

• Every test needs to use assertions
  • Assert(A==B,"Reason why Assert Failed")
  • AssertEquals(A==B, "Reason why Assert Failed")
  • AssertNotEquals(A==B, "Reason why Assert Failed")

Rule 9: Test One thing at a time

• Unit Test - Test Driven Development (TDD)