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Mission RIP Table: Migrate to Grid! - Basic

By  
A.Mahdy AbdelAziz
·
On Aug 23, 2017 1:37:00 PM
·

As promised earlier, here is the first and most basic example. As a reference, Gridv7 is the Grid component from Framework 7, while Grid is the latest Grid component in Framework 8. Naturally, you can also migrate straight from Table to the Framework 8 style Grid.

Migrate from Table to Framework 7 Grid

Before starting, we need to remember that the fundamental difference between Table and Grid is that Grid is a pure Component, while Table is a mixture of a Component and a Container at the same time. So whenever we have a Table without an external declaration of Container, we must create one first to be able to use it with Grid:

IndexedContainer container = new IndexedContainer();

 

The declaration of Table and Grid is pretty similar, so replacing:

Table table = new Table("The Brightest Stars");

With:

Gridv7 table = new Gridv7("The Brightest Stars", container);

 

And here I defined the container in the constructor. We can do that in a separate line as well using setContainerDataSource. The important step now is to replace all Container-related calls that were directly using Table, to use container, for example replace:

table.addContainerProperty("Name", String.class, null);

With:

container.addContainerProperty("Name", String.class, null);

 

There is no addItem() API anymore in the Containers. You can not do something like this:

table.addItem(new Object[]{"Canopus", -0.72f}, 2);

But instead:

itemId = container.addItem(2);
itemId.getItemProperty("Name").setValue("Canopus");
itemId.getItemProperty("Mag").setValue(-0.72f);

 

While this sounds like a drawback at first, the main reason behind this architecture was to get rid of manual filling of data components and make them all based on Containers. Basically you should not fill any data components one by one using addItem, that’s why it has disappeared completely in Framework 8.

 

The setPageLength API specifies the height of the Table. Grid’s height can be specified using different methods, that’s why this line:

table.setPageLength(table.size());

Needs to be replaced with two lines:

table.setHeightMode(HeightMode.ROW);
table.setHeightByRows(container.size());
 

Before you feel like you have done everything, there is one small thing missing if you want an exact migration from Table to Grid. You must disable the selection because that was the case by default in Table:

table.setSelectionMode(Gridv7.SelectionMode.NONE);

But in future examples I will ignore this extra line.

 

Related commit: Basic: To Grid v7 first method

 

A perfect migration would involve architecture modernization as well, that’s why I prefer not to stop at this point, and change the way how the data is populated inside this basic Grid. This will also help in future migration to Framework 8.

 

So I define a simple hard coded data and populate it inside the container:

Object[][] data = {
  {"Sirius", -1.46f},
  {"Canopus", -0.72f},
  {"Arcturus", -0.04f},
  {"Alpha Centauri", -0.01f}
};

IndexedContainer container
    = new IndexedContainer(Arrays.asList(data));
 

And this will make it easy to iterate over them while giving values:

for(Object[] item: data) {
  container.getItem(item).getItemProperty("Name")
      .setValue(item[0]);
  container.getItem(item).getItemProperty("Mag")
      .setValue(item[1]);
}
 

This replaces the manual hard coded definition of items. Note that we don’t need to define items anymore, we just set the values.

 

Related commit: Basic: To Grid v7 second method

Migrate to Framework 8 Grid

Grid in Framework 8 is way much simpler, we don’t use Containers nor Property anymore. Grid is parameterized with the type of data you want to display. So instead of:

IndexedContainer container
    = new IndexedContainer(Arrays.asList(data));
Gridv7 table = new Gridv7("The Brightest Stars", container);

We set the data directly into Grid:

Grid<object> table = new Grid<>("The Brightest Stars");
table.setItems(data);
 

We don’t need to define properties manually anymore, nor define items one by one, we can use some lambda magic:

table.addColumn(v -> v[0]).setCaption("Name");
table.addColumn(v -> v[1]).setCaption("Mag");
 

The first part table.addColumn(v -> v[i]) defines how the columns are provided from the given data, and the second part setCaption("Name") is to manually give a name for the column, since we are not using a proper POJO that can help us automatically generate the column names. Later there will be some more examples about this, but now we can see how this first example is easily transformed into a very simple code with the power of Framework 8.

 

Related commit: Basic: To Grid v8

 

Does this give you a good kickstarter for your migration process? Let us know how you feel about it so far in a comment below!

A.Mahdy AbdelAziz
AMahdy is an international technical speaker, Google developer expert (GDE), trainer and developer advocate. Passionate about Web and Mobile apps development, including PWA, offline-first design, in-browser database, and cross platform tools. Also interested in Android internals such as building custom ROMs and customize AOSP for embedded devices. AMahdy.net
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