Few notes about PXAccumulatorAttribute

1. If to inherit from PXAccumulatorAttribute, you'll have access to member _SingleRecord. If to set in constructor to true, you'll configure single record update mode.
2. There is PrepareInsert method. This method intended for updating policy for the data fields.
3. PrepareInsert is invoked within Persist method, before Acumatica framework generates SQL commands for inserted data records.
4. Among paramethers of PrepareInsert method there is PXAccumulatorCollection, which has method Update. In this method it's possible to configure fields which will be updated during PrepareInsert
5. Method Update has following policies: PXDataFieldAssign.AssignBehavior.Initialize ( new value is inserted into the database column only if value is null ), PXDataFieldAssign.AssignBehavior.Replace ( new value replces old value ), PXDataFieldAssign.AssignBehavior.Summarize ( new value is added to the value stored in the database ), PXDataFieldAssign.AssignBehavior.Maximize ( maximum of the new value and the value from the database is saved in the database ), PXDataFieldAssign.AssignBehavior.Minimize ( minimum of the new value and the value form database is saved in the database )

So, in order to implement Accumulator attribute, following steps are needed:

1. Inherit class from PXAccumulatorAttribute

2. Implement PrepareInsert method

3. Implement PersistInserted method.