12.1.2.1.1.11.1.3. Grid – Business Rules for Data Management

In this section of the manual, we’ll explore some useful tips and tricks for managing grids using business rules.

1. How To Add a New Row in a Grid Linked to a Mid-Entity (Many-to-Many) When the Item Does Not Already Exist

To learn how to add a new row in a grid linked to a mid-entity (or mid-table) when the item does not already exist, refer to the following set of instructions:

• Create the two entities that you want to link together (e.g. Product and Supplier)
  • For each entity, create the relevant set of attributes.
• Create a mid-entity with the two foreign keys (e.g. Product_Supplier)
• Create a form associated with the mid-entity
  • Inside the form, add all required controls for the attributes of the child entity (e.g. all attributes of Supplier)
• Create a pre-form action for the form.
  • In the code, create a new domain object for the referenced child entity.

    • Code Example

      if (domainObject.BPMAPP_BCM_Action_ItemFK_ActionItem  null)
      {
        	var actionItem = (Ray.BPMApp.BCM.Model.BPMAPP_BCM_Action_Item)(bpmAppService.UnitOfWork.CreateDomainObject(typeof(Ray.BPMApp.BCM.Model.BPMAPP_BCM_Action_Item)));
         	domainObject.BPMAPP_BCM_Action_ItemFK_ActionItem = actionItem;
         	if (actionItem.BPMAPP_BCM_BCP_ActionItem_Execute_MidsFK_ActionItem  null)
         	{
         		actionItem.BPMAPP_BCM_BCP_ActionItem_Execute_MidsFK_ActionItem = new List<Ray.BPMApp.BCM.Model.BPMAPP_BCM_BCP_ActionItem_Execute_Mid>();
         	}
         	actionItem.BPMAPP_BCM_BCP_ActionItem_Execute_MidsFK_ActionItem.Add(domainObject);
      }

• Configure the governance properties of the grid control (to which the mid-entity is linked).
  • Enable the control’s ‘new’ functionality and set up the corresponding form behavior (‘New Form’).
    • This will allow users to open the previously created form directly from the grid.

*A grid linked to a mid-entity is a common way to manage many-to-many relationships in a database. Essentially, it allows users to have a grid that displays the relationship between two entities, each represented by a separate table.

2. How To Prevent Duplicates in a Grid

To learn how to prevent duplicate entries in a grid, consider the following example:

• In the database, there are two custom entities, Product and Supplier, which have their own corresponding set of attributes.
  • These two entities are linked together by a mid-entity through foreign keys.
• In the Supplier form, there is a grid linked to the mid-entity, which displays the mid-objects, i.e., the supplier’s products.
  • Using the grid, users can add products to the supplier, but each product should only be added once.
    

    **If a user attempts to add the same product again, it should be filtered out in the grid’s code.

    • To achieve this, users must write code to implement the necessary logic.

      • Code Example

        if(domainObject.BPMAPP_Mid_Supplier_ProductsSupplier != null)
        {
        	var productIds = new List();
        	var midsToDelete = new List(); 
        	foreach(var mid in domainObject.BPMAPP_Mid_Supplier_ProductsSupplier)
        	{
        		if(productIds.Contains(mid.BPMAPP_ProductProduct.Id))
        			midsToDelete.Add(mid);
        		else
        			productIds.Add(mid.BPMAPP_ProductProduct.Id);
        	}
        	foreach(var mid in midsToDelete)
        	{
        		bpmAppService.BPMSServices.DomainObjectService.DeleteDomainObject(mid);
        	}
        	domainObject.BPMAPP_Mid_Supplier_ProductsSupplier = domainObject.BPMAPP_Mid_Supplier_ProductsSupplier.Where(m => !midsToDelete.Contains(m)).ToList();
        }

*To see examples of different grid functionalities in action, check out the following applications: Grid Management – Create Copy on Edit and Grid Management – Multi-Column Conditions.