View source for Scout/Tutorial/5.0/Minicrm/Write the first page

{{ScoutPage|cat=Tutorial 5.0}}
{{note|Scout Tutorial|This page belongs to the [[{{BASEPAGENAME}}/Minicrm Step-by-Step|Minicrm Step-by-Step Tutorial]]. It explains how to create your first page in your project and fill it with data from the database. You need to [[{{BASEPAGENAME}}/Set up SQL Service|connect a database to your application]] in order to continue.}}

A typical Eclipse Scout application consists of multiple '''outlines'''. Think of it as a folder hierarchy. Each "folder" is called a '''page'''. These pages come '''with nodes''' (a list of child pages) or '''with a table''' (a table filled with rows of data from a data source such as a database). The '''table''' has named '''columns'''. We need to create models for all of these.

If we want to fill the tables with data, we need to create a '''service''' on the server side. This service will get data from the database and return ''tabular data'': data arranged in rows and columns which we can use to fill the tables we created on the client side.

Once we have all that we're ready to [[{{BASEPAGENAME}}/Add_a_search_form|add a search form]] to our application.

== What are we talking about? ==

When we talk about ''outlines'' and ''pages'', think of a simple application. In this tutorial we're creating a miniature CRM. Here's what it may look like, using the Eclipse Scout terminology:

# one outline for companies and persons
## the companies page shows a table with rows from the company table on the database
## the persons page shows a table with rows from the person table on the database
## for every person there is a list of nodes naming all the child pages
# there may be other outlines for different tasks or topics, such as marketing campaigns

[[Image:Scout Pages and Outlines.jpg|900px]]

If you look at the diagram above, there are some interesting things to note.

# the outline itself acts like a page with nodes -- it just shows the titles of the child pages (persons and companies)
# there can be only one child page for a page "with table" -- every row in the table has the same child
# the title of a child page underneath a table is not shown -- by default the first visible column of the table replaces whatever the name was (in the example above "Catherine" replaces whatever the name of the Person Details Page was)

In this tutorial, our '''first page''' will be the '''company''' table page. The '''standard outline''' is a prerequisite, so we'll start there.

All of these structures are strictly client-side structures. The '''server''' couldn't care less about how the various services it provides will get used. The only thing we need on the server side is '''a service that returns tabular company data'''.


== Add a Page to the Outline ==

Add a new page to your StandardOutline. Right-click on the ''Child Pages'' node of your ''StandardOutline'' and then choose ''New Page...''.

[[Image:Scout.3.9.first_page.new_page.menu.png]]

From the dropdown list choose '''AbstractPageWithTable''', then click next.

[[Image:Scout.3.9.first_page.new_page.wizard.png]]

Now enter the name for the new table page: ''Company''.

If there is no appropriate multilingual text, pick ''New translated text...'' from the list and provide a key and a default translation.

[[Image:Scout.3.9.new_translated_text.png]]

[[Image:Scout.3.9.new_entry.png]]

To close the translation dialog click Finish.

{{note|Text Property Files|Creating a new translated text will create entries in property files handling translations. ''Texts.properties'' is the file for the default language (the only language available until you add other).}}

Eclipse Scout also comes with an editor to '''edit all the property files for multilingual texts''' in one go. If you expand the ''shared'' node in your Eclipse Scout project, expand ''Text Provider Services'' and click on ''DefaultTextProviderService''. Click the  link in the Scout Object properties view. With this editor you have the possibilty to manage your translated text entries (add, modify, remove), to add or remove a language, to export your entries and so on. {{ScoutLink|SDK|NLS Editor|More information about the NLS Editor here}}

To open the NLS Editor as shown below click on the link ''Open NLS Editor ...' in the Scout Object Properties view.

[[Image:Scout.3.9.text_provider_service.png]]

Back to the ''CompanyTablePage'' example: pick ''Company'' from the list (create a new translated text if you haven't done so already) and click ''Finish''.

[[Image:Scout.3.9.first_page.new_page.wizard2.png]]

When you now expand the ''Child Pages'' folder below your ''StandardOutline'', you'll find the new ''CompanyTablePage''. When you expand the node ''Table'', you'll find a folder ''Menus'' and ''Columns''. Below ''Columns'' we will now '''add the columns''' that are needed to display the company data.

[[Image:Scout.3.9.first_page.explorer.png]]

{{note|Files|Creating the Company Table Page has created the file ''eclipse.org.minicrm.client.ui.desktop.outlines.pages/CompanyTablePage.java'' and it has added code to ''eclipse.org.minicrm.client.ui.desktop.outlines/StandardOutline.java''. The newly created method '''execCreateChildPages''' in ''StandardOutline'' shows how child pages are instantiated and added to the list.}}

== Add colums to the table == 

The next step is '''adding columns to the table'''. Add a column for the primary key (''CompanyNrColumn''), one for the company's short name (''ShortNameColumn'') and one for the company's name (''NameColumn'').

The context menu for creating a new table column is on the ''Columns'' node right below the page's table.

[[Image:Scout.3.9.first_page.new_column.menu.png]]

First you have to choose a '''template''' for your column. The template used depends on the '''data type''' of your data and the '''format''' you want to use when displaying it. Eclipse Scout will attempt to cast your data types appropriately.

Choose ''Long Column'' for the first column and ''String Column'' for the remaining columns.

[[Image:Scout.3.9.first_page.new_column.wizard1.png]]

''CompanyNrColumn'' is going to be an invisible column. Thus, it requires no name. Just provide the ''Class Name''.

The remaining columns get multilingual texts for their labels, just like everything else in an Eclipse Scout application.

[[Image:Scout.3.9.first_page.new_column.wizard2.png]]

{| cellspacing=10 style="border-top: 1px solid black; border-bottom: 1px solid black; margin: 1em; "
!Template
!Name
!TypeName
!Width
!Displayable
!Primary Key
|-
|LongColumn
|(none)
|CompanyNrColumn
|(irrelevant)
|no
|yes
|-
|StringColumn
|Short Name
|ShortNameColumn
|200
|yes
|no
|-
|StringColumn
|Name
|NameColumn
|200
|yes
|no
|}

{{note|Inner Classes|A '''page with table''' is a single Java class. In this example, we're talking about the '''CompanyTablePage'''. The '''table''' itself is an '''inner class''' of the page. The '''columns''' are '''inner classes''' of the table. Take a look at the source files to see how it works. The Scout SDK parses the Java code in order to create its model, and the Scout runtime does the same thing. You'll also note that '''annotations''' such as <tt>@Order(2000.0)</tt> are used to determine the order of columns in the table.}}

== Column Width == 

If you restart your client, you will see that the table layout is '''not optimal'''.

The '''column width''' could be improved. The table has a property called ''Auto resize columns'' and every column has a property called ''Width''. You can either specify a higher width for all of your columns or you can tell your table to auto resize all columns. When auto resizing, the available width is shared by all columns.

{{warning|Auto Resizing|Generally speaking you should only use ''auto resize columns'' when '''prototyping'''. In a real application, most '''numbers and dates should be in fixed width columns'''. In addition to that, in some cases you will end up with a lot of columns. Twenty, thirty, and more columns are not unheard of. In this case, fixed columns width and (a lot of) horizontal scrolling is the only solution. Auto resized columns would result in an unreadable mess.}}

If you're not sure, use a width of 200 for text columns.

[[Image:Scout.3.9.first_page.column_properties.png]]

{{note|Properties|Setting properties in the Scout SDK needs to leave traces in the Java code because there is no other storage medium. If you look at the property view, you'll note that all the '''bold''' properties have non-default values. The property names act as links. They'll take you to the source code. Setting the width of a column to 200 results in a method being defined for the inner class modeling the column: <tt>protected int getConfiguredWidth() { return 200; }</tt>. This is how Scout properties are mapped: By overriding methods of the abstract classes the framework provides (such as <tt>AbstractStringColumn</tt> etc.).}}

== Hiding Columns ==

In addition to that, users are typically '''not interested in primary keys'''. You should hide ''CompanyNrColumn'' from the user.

You can do that by unticking the '''Visible''' property on the column. Users can make invisible columns visible, however. If you want to prevent this (and in this case you do), untick the '''Displayable''' property. To mark the column as a primary key you have to tick the '''Primary Key''' property.

Then it will look like this:
[[Image:Scout-NewColumn2.PNG]]

Note: There are only two columns

{{note|Visible vs. Displayable Columns|An invisible column is only invisible initially. Users can right-click on the column headers of a table and ''organize'' their columns. This is where users can show and hide columns, and this is where they can change their order. '''Invisible columns can be made visible''' using this dialog. If you want to prevent users from making invisible columns visible, you must make them ''not displayable''.}}

Sometimes '''invisible but displayable columns''' are used if a certain table is used like a ''report'' for slightly different target users. Some users are interested in a certain subset of columns, other users are interested in a different subset. Instead of preparing a customized table for every target user, you can provide a single table for all users with specialized columns being invisible but displayable. Every user can then configure the visibility of the particular extra columns they are interested in.

== The Flow of Data ==

Now that we have our user interface, we need to think about '''flow''': how does the data from the database get into our table? 

Our table page has a method called '''execLoadData'''. We will override its default definition and call our '''outline service''' instead. In order to do this, we'll get a '''proxy''' from the service registry using the <tt>SERVICES</tt> object and the desired interface (''IStandardOutlineService.class'') as the key. We call the '''getCompanyTableData''' method on the proxy, it gets passed to the server, the method is called, the database is queried via the '''SQL''' object, the tabular data is returned to the proxy, it is returned to our function call, finally it will be used to populate the ''CompanyTablePage'' model. This in turn will be used to populate the user interface.

[[image:Scout_Table_Details_V2.png|800x1000px]]

== Create a new service operation in StandardOutlineService ==

In order to fill the table in our ''CompanyTablePage'' we need to have a '''service''' available on the server side. This service will contact the database and retrieve the data we need on the client.
The StandardOutlineService and the interface IStandardOutlineService has already been created.

Now we need to add a service operation to the service.
To do so expand the node ''Outline Services'' and you'll see the ''StandardOutlineService''. Right-click on it and choose '''New Service operation'''.

[[Image:Scout.3.9.first_page.new_service_operation.menu.png]]

Choose ''getCompanyTableData'' as the name, and the table page data <tt>CompanyTablePageData</tt> as the return type. 

[[Image:Scout.4.0.first_page.new_service_operation.wizard.png]]

To ensure the import of the right type press '''Ctrl-Space after''' ''CompanyTablePageData'', then click ''Finish''. 
Now the operation will be added to the interface and the service itself.

When naming service operations that provide tabular data for use in table pages, following the pattern '''get'''Something'''TableData''' is a convention and considered good practice.

== Load data on the server ==

Open the implementation of ''getCompanyTableData'' either by expanding the node ''StandardOutlineService'' and double-clicking on ''getCompanyTableData'' or by opening the class ''StandardOutlineService'' directly (''Ctrl-Shift-T'') and scrolling down to ''getCompanyTableData''. This is the place where we have to add an SQL statement which retrieves the data from the database.

The DB you've downloaded contains the following two tables:

[[Image:Company.jpg]]

[[Image:Person.jpg]]

Eclipse Scout provides a base service called <tt>SQL</tt>. In order to access the database and select data, just call <tt>SQL.select(...)</tt>.

The first parameter to <tt>SQL.selectInto</tt> is the '''SELECT statement'''.

<source lang="java">
public class StandardOutlineService extends AbstractService implements IStandardOutlineService {

  @Override
  public CompanyTablePageData getCompanyTableData() throws ProcessingException {
    CompanyTablePageData pageData = new CompanyTablePageData();

    SQL.selectInto("" +
        "SELECT COMPANY_NR," +
        "       SHORT_NAME," +
        "       NAME" +
        " FROM  COMPANY" +
        " INTO :{companyNr}, :{shortName}, :{name}",
        pageData);

    return pageData;
  }
}
</source>

Add the method implementation in the StandardOutlineService class.

<tt>SQL.selectInto</tt> takes a String query as first parameter and '''Bind Bases''' as vararg (0 to N parameters). They are needed as input binds if you need constraints (a WHERE clause with bind variables) in your SELECT statement or as input binds after the INTO clause.
The pageData object is passed as output binds. The curly brackets indicate that the binds are used in batch mode to handle the multiple rows of the result set.

== Display data on the client ==

The last thing to do now is to add the call to the ''getCompanyTableData'' service operation, for this we need to overwrite the method ''AbstractPageWithTable.execLoadData(SearchFilter)''. Go back to your ''CompanyTablePage'', in the lower part of the properties view click on the ''+'' right to '''Exec Load Data''' in order to create this method in your table page.

[[Image:Scout.4.0.first_page.exec_load_table_data.png]]

Now you can use the convenience accessor class '''SERVICES''' to find the required service using the ''IStandardOutlineService'' interface class and call ''getCompanyTableData'' to load the data in your TablePage.

<source lang="java">
  @Override
  protected void execLoadData(SearchFilter filter) throws ProcessingException {
    importPageData(SERVICES.getService(IStandardOutlineService.class).getCompanyTableData());
  }
</source>

'''Restart your application'''

[[Image:Scout.3.9.first_page.client_swt.png]]