Step 1: Create a custom function  

1. Navigate to Setup > Automation > Functions and click Create Function.
   
2. Enter the following details and click Save:
   
1. Function Name: CreateEstimateFromWO
   
2. Module: Work Order
   
3. In the Deluge Script Editor, enter the following script:
   
   

   contact_id = work_order.get("Contact").toMap().get("id"); contact_resp = zoho.fsm.getRecordById("Contacts",contact_id); invoice_contact_id = contact_resp.get("data").toMap().get("ZBilling_Id"); listVar = List(); Service_Line_Item_List = work_order.get("Service_Line_Items").toList(); for each  line in Service_Line_Item_List {  line_map = line.toMap();  line_name = line_map.get("Service").toMap().get("name");  line_id = line_map.get("Service").toMap().get("id");  line_resp = zoho.fsm.getRecordById("Service_And_Parts",line_id);  invoice_line_id = line_resp.get("data").toMap().get("ZBilling_Id");  mapVar = Map();  mapVar.put("item_id",invoice_line_id);  mapVar.put("name",line_name);  mapVar.put("rate",line_map.get("List_Price"));  mapVar.put("quantity",line_map.get("Quantity"));  listVar.add(mapVar); } Part_Line_Item_List = work_order.get("Part_Line_Items").toList(); for each  line in Part_Line_Item_List {  line_map = line.toMap();  line_name = line_map.get("Part").toMap().get("name");  line_id = line_map.get("Part").toMap().get("id");  line_resp = zoho.fsm.getRecordById("Service_And_Parts",line_id);  invoice_line_id = line_resp.get("data").toMap().get("ZBilling_Id");  mapVar = Map();  mapVar.put("item_id",invoice_line_id);  mapVar.put("name",line_name);  mapVar.put("rate",line_map.get("List_Price"));  mapVar.put("quantity",line_map.get("Quantity"));  listVar.add(mapVar); } values = Map(); values.put("customer_id",invoice_contact_id); values.put("line_items",listVar); response = zoho.invoice.create("Estimates","<orgId>",values); info response;

Additionally ensure that the status of the internal connections for Zoho FSM, and Zoho Invoice integration tasks are Connected. The green dot [] indicates that the connection is Connected.

Step 2: Create a workflow rule  

1. Go to Setup > Automation > Workflow Rules and click Create Workflow.
   
2. Enter the following details, then click Next:
   
1. Module: Work Orders
   
2. Rule Name: CreateEstimateForWO
   
3. Description: Generate an Estimate in Zoho Invoice when a Work Order is created in Zoho FSM.
   
   
   
   
3. Select the rule trigger as Created and click Next.
   
   
   
   
4. Select the rule criteria as To all Work Orders and click Next.
   
   
   
   
5. Click +Action and select Function.
   
   
   
   
6. Select Existing Functions and click Next.
   
   
   
   
7. Select the custom function created in the previous step.
   
   
   
   
8. Click Save.
   
   

Testing the usecase