Anonymous code for bulk update of text field

Question

I have a text field named TestId in the object test which is capturing the Id of the record.Actually I have used an automation such as flow to update the value in the text field. Since I cannot make formula fields searchable I had to convert it to a text field. Working for newly created objects but I have to update the earlier created records with this value using anonymous code: How do I do this? Almost 20,000 records to be updated.

List <Test__c> test=testList=[Select Id, Name, TestId From Test__c];
for(test:testList){

}

Answer 1

Like I said in my comments you can use dataloader and export the data and perform update operation with out any change so the flow gets invoked and the field value gets calculated.

If you want to execute in anonomous block you can perform dummy update as below.

List <Account>acclist=[Select Id, Name From Account];
List<Account> accounttoupdate= new List<Account>();
for(Account t:acclist){   
accounttoupdate.add(t);
}
update accounttoupdate;

In both the process you are just doing dummy update for the records only so that the flow gets invoked and value gets calculated

Answer 2

You can work with Lists

for (List<Test__c>testList : [Select Id, Name, TestId From Test__c WHERE TestId = NULL LIMIT 9000]) {
    for(Test__c test : testList){
        // update code here
    }

    update testList;
}

https://developer.salesforce.com/docs/atlas.en-us.234.0.apexcode.meta/apexcode/langCon_apex_SOQL_VLSQ.htm

Thanks