Value calculate for each row in a table

Support
#1

Hello,

following the quick start video of part 4, I calculated the total value of order in orderEdit with addCollectionChangeListener.

To do this I used a transient attribute. What I want to do now is to calculate the same value in orderBrowse for each row in the table.

In general I would like an example of calculation of values for each row of a table,
a simple price multiplied by quantity.

Thanks in advance.

#2

Hi,

you have two options for calculatable values in a Table:

  1. MetaProperty
  2. Table generated column

In the first case you can define simple calculation logic right in the entity:


@Table(name = "METADEMO_PRODUCT")
@Entity(name = "metademo$Product")
public class Product extends StandardEntity {
    private static final long serialVersionUID = -8767718329931420801L;

    @Column(name = "TITLE", nullable = false, unique = true)
    protected String title;

    @Column(name = "COUNT_", nullable = false)
    protected Integer count;

    @Column(name = "PRICE", nullable = false)
    protected Integer price;

    @MetaProperty(related = {"price", "count"}) // it depends on price and count
    public Integer getCost() {
        return getCount() * getPrice();
    }

    // ... getters and setters
}

And then you can define it in a Table as usual column:


<table id="productsTable"
       width="100%">
    <columns>
        <column id="title"/>
        <column id="count"/>
        <column id="price"/>
        <column id="cost"/>
    </columns>
    <rows datasource="productsDs"></rows>
</table>

In the second case column functionality will be limited if there is no corresponding attribute in an entity, for example it will be non sortable and grouping of such a column is not supported. But in generated columns you can use UI context and values entered by user in UI:


public class ProductBrowse extends AbstractLookup {
    @Inject
    private Table<Product> productsTable;
    @Inject
    private ComponentsFactory componentsFactory;

    @Override
    public void init(Map<String, Object> params) {
        super.init(params);

        productsTable.addGeneratedColumn("cost", entity -> {
            Label label = componentsFactory.createComponent(Label.class);
            label.setValue(entity.getCount() * entity.getPrice());
            return label;
        });
    }
}

If you have repeated logic in your application you can always extract it to some usual Java class and call it from MetaProperty or generated column.

#3

Thanks for your response Yuriy.

Still referring to the example in the quick start part 4, I was trying to @Inject CollectionDatasource for Order entity but in the init method is null, even though I do not understand why …

However, if I want to calculate in browserOrder the total order for each row in the table, which depends on the sum of the order lines, how would you do?

Be patient, I am at the beginning and a little confused.

Thank you.

#4

I’ve checked quick start part 4 and everything works as expected. Could you please attach small demo project where you have null CollectionDatasource in the init method?

In case of simple calculation of totals I would use simple meta property with one getter method defined in an Entity class, because I will be able to use this logic in all my screens and services and this formula is small enough to not extract it to a separate class/service.

#5

Thanks Yuriy,

I was able to calculate the total I requested to you, both with my java class, either with a ServiceBean by different methods, both with EntityManager, either with DataManager, both using getLines of the Order entity.

I am very satisfied and I am continuing to study your documentation.

Thanks again for your help.