AttachmentTriggerHandler

AttachmentTriggerHandler

/**
 *  AttachmentInsertUpdateTriggerMVN
 *  Created By:     Florian Hoehn
 *  Created On:     15/05/2017
 *  Description:    This is a trigger class that creates ...
 *                  
 **/
public class AttachmentInsertUpdateTriggerMVN implements TriggerHandlerMVN.HandlerInterface {
    private Map<String, Program_Member_Attachment_Setting_MVN__mdt> programMemberAttachmentSettings {
        get {
            Map<String, Program_Member_Attachment_Setting_MVN__mdt> programMemberAttachmentSettings = new Map<String, Program_Member_Attachment_Setting_MVN__mdt>();
                for(Program_Member_Attachment_Setting_MVN__mdt setting : [SELECT SObject_API_Name_MVN__c, Program_Member_Field_API_Name_MVN__c, Type_MVN__c 
                                                                            FROM Program_Member_Attachment_Setting_MVN__mdt]) {
                    programMemberAttachmentSettings.put(setting.SObject_API_Name_MVN__c, setting);
            }
            return programMemberAttachmentSettings;
        }
    }

    public void handle() {
        if(Trigger.isInsert || Trigger.isUpdate) {
            if(Trigger.isAfter) {
                // arranging attachments by parentIds and parentIds by their type
                Map<String, Set<Id>> parentIdsByType = new Map<String, Set<Id>>();
                Map<Id, List<Attachment>> attachmentsByParentId = new Map<Id, List<Attachment>>();
                for (Attachment attachment : (List<Attachment>) Trigger.new) {
                    List<Attachment> attachmentList = new List<Attachment>();
                    if(attachmentsByParentId.get(attachment.ParentId) != null) {
                        attachmentList = attachmentsByParentId.get(attachment.ParentId);
                    }
                    attachmentList.add(attachment);
                    attachmentsByParentId.put(attachment.ParentId, attachmentList);
                    
                    String parentIdType = attachment.ParentId.getSObjectType().getDescribe().getName();
                    Set<Id> parentIds = new Set<Id>();
                    if(parentIdsByType.get(attachment.ParentId) != null) {
                        parentIds = parentIdsByType.get(parentIdType);
                    }
                    parentIds.add(attachment.ParentId);
                    parentIdsByType.put(parentIdType, parentIds);
                }

                // create documents by pulling the program member lookup fields from the setting and using a dynamic query to get the content
                // ATTENTION: 
                // SOQL in for loop for each parent type: means each attachment with a different so long as we do not have 100 different parent types in one go it's fine...
                List<Program_Member_Document_MVN__c> newProgramMemberDocuments = new List<Program_Member_Document_MVN__c>();
                for(String parentIdType : parentIdsByType.keySet()) {
                    Set<Id> parentIdsToSelect = parentIdsByType.get(parentIdType);
                    if(programMemberAttachmentSettings.get(parentIdType) != null) {
                        for(SObject obj : Database.query('SELECT ' + programMemberAttachmentSettings.get(parentIdType).Program_Member_Field_API_Name_MVN__c + ' FROM ' + parentIdType + ' WHERE Id IN: parentIdsToSelect')) {
                            for(Id parentId : parentIdsToSelect) {
                                for(Attachment attachment : attachmentsByParentId.get(parentId)) {
                                    newProgramMemberDocuments.add(
                                        new Program_Member_Document_MVN__c(
                                            Attachment_Id__c = attachment.Id,
                                            Title_MVN__c = attachment.Name,
                                            Program_Member_MVN__c = (Id)obj.get(programMemberAttachmentSettings.get(parentIdType).Program_Member_Field_API_Name_MVN__c),
                                            Type_MVN__c = programMemberAttachmentSettings.get(parentIdType).Type_MVN__c
                                        )
                                    );
                                }
                            }
                        }
                    }
                }
                upsert newProgramMemberDocuments Attachment_Id__c;
            }
        }
    }
}