Using this to get below working:

    public class t12345 implements Database.Batchable<sObject> {

        String query;
        Boolean xyz;

        public t12345(String query){
            this.query= query;

public Database.QueryLocator start(Database.BatchableContext bC){      
    return Database.getQueryLocator(query);

and when I run below from developer console,

    Type api = Type.forName('t12345');
    Object apiCall = JSON.deserialize('{"query":"hello world"}',api);
Database.executeBatch((Database.Batchable<sObject>) apiCall);

above execution results in error Argument 1 cannot be null which is coming from start method of batch where query value is still null as constructor with query is not invoked

  • 1
    You should include your error message verbatim if you have one... – Adrian Larson Jan 16 '18 at 19:20

If you try:

MyClass instance = new MyClass(); // or any other approach to construction

You should get this error:

System.TypeException: Invalid conversion from runtime type MyClass to Database.Batchable

If you want to cast a class to Database.Batchable<SObject>, it has to implement that interface.

Instead of:

public class MyClass { ... }


public class MyClass implements Database.Batchable<SObject> { ... }

This adjustment will mean you actually have to define the methods enforced by that interface.

  • Thansk Adrian. I am preparing object in t12345 which is calling batch class that uses batchable interface. I corrected my question accordingly. Goal is to call parameterized constructor in batch class. I tried to generalize my error. sorry for any confusuion – sf_user Jan 16 '18 at 19:27

You cannot generically call a non-no-argument constructor. While other object-oriented languages have methods for doing this, Apex Code does not have any support for this.


Your JSON.deserialize will (probably) set the fields but not via the constructor you have the System.debug in. (Constructors can have an arbitrary signature but the field names are effectively a fixed signature.)

  • I am trying to call batch using that object return type. Updated question above. – sf_user Jan 16 '18 at 19:18

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