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Difference between revisions of "Scout/Tutorial/3.7/Minicrm/Write the first page"

< Scout‎ | Tutorial‎ | 3.7
(Load data on the server)
(Load data on the server: SQL Statement)
Line 164: Line 164:
 
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.
 
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 tables:
+
The DB you've downloaded contains the following two tables:
  
 
[[Image:Company.jpg]]
 
[[Image:Company.jpg]]
Line 171: Line 171:
  
 
As described in the [[Scout Overview]], Scout provides a base service called <tt>SQL</tt>. In order to access the DB and select data just call <tt>SQL.select(...)</tt>.
 
As described in the [[Scout Overview]], Scout provides a base service called <tt>SQL</tt>. In order to access the DB and select data just call <tt>SQL.select(...)</tt>.
 
{{warning|Order Considered Relevant|When writing your SELECT statement pay attention to specify the db columns in exactly the same order as the order of your table columns. This is necessarily so because we're just passing an untyped <tt>Object[][]</tt> along. This is an unfortunate consequence of the shortcut we used. As you can see, there are benefits (no packing and unpacking of the tabular data) and drawbacks (the compiler does not check types) to using an untyped <tt>Object[][]</tt>.}}
 
  
 
The first parameter to <tt>SQL.select</tt> is the '''SELECT statement'''.
 
The first parameter to <tt>SQL.select</tt> is the '''SELECT statement'''.
 +
 +
<pre>
 +
public class StandardOutlineService extends AbstractService implements IStandardOutlineService {
 +
 +
  public Object[][] getCompanyTableData() throws ProcessingException {
 +
    return SQL.select("" +
 +
        "SELECT COMPANY_NR," +
 +
        "      SHORT_NAME," +
 +
        "      NAME" +
 +
        " FROM  COMPANY");
 +
  }
 +
}
 +
</pre>
 +
 +
{{warning|Order Considered Relevant|When writing your SELECT statement pay attention to specify the db columns in exactly the same order as the order of your table columns. This is necessarily so because we're just passing an untyped <tt>Object[][]</tt> along. This is an unfortunate consequence of the shortcut we used. As you can see, there are benefits (no packing and unpacking of the tabular data) and drawbacks (the compiler does not check types) to using an untyped <tt>Object[][]</tt>.}}
  
 
The second parameter to <tt>SQL.select</tt> are the '''Bind Bases'''. They are needed if you need constraints (a WHERE clause with bind variables) in your SELECT statement. For the moment we leave it empty.
 
The second parameter to <tt>SQL.select</tt> are the '''Bind Bases'''. They are needed if you need constraints (a WHERE clause with bind variables) in your SELECT statement. For the moment we leave it empty.

Revision as of 07:56, 12 October 2010

Note.png
Scout Tutorial
This page belongs to the The Scout documentation has been moved to https://eclipsescout.github.io/.. It explains how create your first page in your project and fill it with data from the database. You need to The Scout documentation has been moved to https://eclipsescout.github.io/. 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 comes with nodes (a list of child pages) or with table (a table filled with rows of data from a data sources 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.

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 have, using the Eclipse Scout terminology:

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

Scout Pages and Outlines.jpg

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

  1. the outline itself acts like a page with nodes -- it just shows the titles of the child pages (persons and companies)
  2. there can be only one child page for a page "with table" -- every row in the table has the same child
  3. 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 prerequesite for it, so we'll start there.

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

Add an Outline first

Since a page can only be contained within an Outline, you need to define the Outline first. Open the client node in Eclipse Scout and expand the tree until you get to the Desktop node. Do a right click on that node and choose New Outline....

Newoutline.jpg

Choose Standard as the name and make sure the checkbox Add to Desktop is ticked. Then click Finish.

Newoutlinewizard.jpg

Note.png
Multilingual Texts
If you type Standard into the name field, you'll see all sorts of texts in the language of your locale. If you're not sure whether the string you picked is the right one, you can right-click it and choose Modify Entry... from the context menu. This will show you the key and all the translations. If you're still not happy, just create a new multilingual text: type Standard into the name field and pick New translated text... from the list.


If you expand the Desktop, you should see the newly created StandardOutline.

Standardoutline.jpg

Note.png
Files Created
If you switch to the Java Perspective you can look at the file created: eclipse.org.minicrm.client.ui.desktop.outlines contains the new StandardOutline.java. If you see the key "SC_Label_UseDefaults" being used in the source code, then you might have picked a multilingual text you did not intend to. Go back to the StandardOutline in the Scout Perspective and modify the entry for the name as discussed above in the note on multilingual texts.


Add a page to the Outline

Now you can add a new page to your StandardOutline. Right click on the Child Pages node of your StandardOutline and then choose New Page....

Newpage.jpg

From the dropdown list choose AbstractPageWithTable then click next.

Newtablepage.jpg

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.

Newtext.jpg

Companytext.jpg

Note.png
Files Changed
Creating a new translated text will create an entry in Texts.java and appropriate property files: Texts.properties for the default language, Texts_de.properties for German, and so on). You can find these files in the Java Perpective under eclipse.org.minicrm.shared/resources/texts.


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, activate Texts and click on open nls editor link in the Scout Object properties view, you can manage all your application's texts.

Nls.jpg

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.

Companytablepage.jpg

When you expand now 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.

Finishedcompanytablepage.jpg

Note.png
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 shortname (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.

Newcolumn.jpg

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.

Columntemplate.jpg

CompanyNrColumn is going to be an invisible column. Thus, it requires no name. Just provide the Type Name. The remaining columns get multilingual texts for their labels, just like everything else in an Eclipse Scout application.

Newcolumnname.jpg

Note.png
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 to see how that 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 @Order(30.0) 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.

Tableprops.jpg Columnprops.jpg
Warning2.png
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.


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.

Organize.jpg

Note.png
Visible and Displayable Colums
An invisible 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 one single table for all users with specialized columns being invisible but displayable. Every user then gets to show the particular extra columns they are interested in.

Create an Outline Service

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.

First, we need to create an OutlineService. Go to the server node in your Eclipse Scout project, expand it, go to Outline Services, right click and choose New Outline Service....

Newoutlineservice.jpg

Note.png
Service Types
Services are grouped by type on the server side. Outline services are used by the pages "with table" in an outline. Process services are used by forms (dialogs). Lookup Services are used by items showing a list of values (smartfields, listboxes).


As name choose StandardOutlineService since this OutlineService goes together with your StandardOutline (hence all the TablePages that will in your StandardOutline in the end will call a service operation in the StandardOutlineService at the end).

Standardoutlineservice.jpg

Optional: If you click Next, you will see that the Scout SDK will do a Service Proxy Registration for you in the client plugin of your project. This will support for calling this service's operation from within the client as well.

Servicereg.jpg

Note.png
Files Affected
If you create the outline service with the default service proxy registration, this will register the service in eclipse.org.minicrm.client/plugin.xml. The service interface is shared between client and server and therefore ends up in eclipse.org.minicrm.shared.services.outline/IStandardOutlineService.java. The service implementation itself is in eclipse.org.minicrm.server.services.outline/StandardOutlineService.java. The service is also registered in eclipse.org.minicrm.server/plugin.xml.


Click on Finish in order to create the new service.

Idea.png
Organisation Alternatives
There are alternatives to the suggestion above. If you have one big service with a method for every page with table in an outline, you will end up with a big class file. If your outline is big enough such that mutliple developers will be working on it at the same time, this will lead to a lot of merging in your version control system. An alternative is to create a separate service per page with table. This results in a lot more classes and less merge conflicts in a crowded project.


Expand the node Outline Services and you'll see the new StandardOutlineService. Right click it and choose New Service operation.

Newserviceop.jpg

Choose getCompanyTableData as the name, and a double object array Object[][] as the return type and click Finish.

Getcompanytabledata.jpg

Note.png
Object[][]
Why aren't we using typed data to communicate between client and server? On the client side, we have a generic load table data method that needs to return Object[][]. It will call the service we just created. Thus, using Object[][] when sending tabular data from the server to the client is nothing but a shortcut.


Naming service operations that provide tabular data for use in table pages using the pattern getSomethingTableData 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:

Company.jpg

Person.jpg

As described in the Scout Overview, Scout provides a base service called SQL. In order to access the DB and select data just call SQL.select(...).

The first parameter to SQL.select is the SELECT statement.

public class StandardOutlineService extends AbstractService implements IStandardOutlineService {

  public Object[][] getCompanyTableData() throws ProcessingException {
    return SQL.select("" +
        "SELECT COMPANY_NR," +
        "       SHORT_NAME," +
        "       NAME" +
        " FROM  COMPANY");
  }
}
Warning2.png
Order Considered Relevant
When writing your SELECT statement pay attention to specify the db columns in exactly the same order as the order of your table columns. This is necessarily so because we're just passing an untyped Object[][] along. This is an unfortunate consequence of the shortcut we used. As you can see, there are benefits (no packing and unpacking of the tabular data) and drawbacks (the compiler does not check types) to using an untyped Object[][].


The second parameter to SQL.select are the Bind Bases. They are needed if you need constraints (a WHERE clause with bind variables) in your SELECT statement. For the moment we leave it empty.

Sql.jpg

Display data on the client

The last thing to do is now to add the call to the getCompanyTableData service operation, for this we need to overwrite the method AbstractPageWithTable.execLoadTableData(SearchFilter). Go back to your CompanyTablePage, in the lower part of the properties view exec click on Exec Load Table Data in order to create this method in your tablepage. When it asks you wether to create the create the method, click on Yes.
Execload.jpg

Now you can use the convenience accessor class SERVICES to lookup your IStandardOutlineService class and then call the method getCompanyTableData to load the data in your TablePage. Now restart your application and enjoy :-)
Services.jpg

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