Difference between revisions of "EDT:Tutorial: RUI With DataBase Lesson 6"

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= Lesson 6: Add code for the service functions =
 
= Lesson 6: Add code for the service functions =
  
In EGL, I/O statements such as '''add''' and '''get''' access
+
In EGL, I/O statements such as '''add''' and '''get''' access data that resides in different kinds of persistent data storage, from file systems to queues to databases. The coding is similar for the different cases.
data that resides in different kinds of persistent data storage, from
+
file systems to queues to databases. The coding is similar for the
+
different cases.
+
  
In this lesson, you add functions that access rows in
+
In this lesson, you add functions that access rows in a relational database. Add the functions in order, before the final '''end''' statement in SQLService.egl.
a relational database. Add the functions in order, before the final '''end''' statement
+
in SQLService.egl.
+
  
 
== Create binding to database connection ==
 
== Create binding to database connection ==
  
In Lesson 3, you defined a database connection named '''Derby'''.   Use these steps to use the '''Derby'' connection from your SQL service.   
+
In Lesson 3, you defined a database connection named '''Derby'''. Use these steps to use the '''Derby'' connection from your SQL service.   
  
#EGL projects have associated deployment descriptor ('''.egldd''') files.   Click on '''PaymentService''' in the project explorer and select '''Properties > EGLDevelopmentDeploymentDescriptor" to see that file '''PaymentService.egldd''' was created when you defined project '''Payment Service'''.  Click on '''OK''' to close the properties window.[[Image:EDT_Tutorial_edt_richui_sql06_deployment_descriptor.jpg|Deployment descriptor property for service project.]]
+
#EGL projects have associated deployment descriptor ('''.egldd''') files. Click on '''PaymentService''' in the project explorer and select '''Properties > EGLDevelopmentDeploymentDescriptor" to see that file '''PaymentService.egldd''' was created when you defined project '''Payment Service'''.  Click on '''OK''' to close the properties window.[[Image:EDT_Tutorial_edt_richui_sql06_deployment_descriptor.jpg|Deployment descriptor property for service project.]]
 
#Open file '''PaymentService.egldd''' with the EGL employment descriptor editor.    [[Image:EDT_Tutorial_edt_richui_sql06_open_deployment_descriptor.jpg|Open deployment descriptor for service project.]]
 
#Open file '''PaymentService.egldd''' with the EGL employment descriptor editor.    [[Image:EDT_Tutorial_edt_richui_sql06_open_deployment_descriptor.jpg|Open deployment descriptor for service project.]]
 
#Select the '''Resource Bindings''' folder
 
#Select the '''Resource Bindings''' folder
Line 30: Line 25:
 
#Close file '''PaymentServices.egldd'''
 
#Close file '''PaymentServices.egldd'''
  
== Using an SQL resource binding in service program
+
== Using an SQL resource binding in service program ==
  
 
Insert a dataSource variable in the service program following the program name:<code>
 
Insert a dataSource variable in the service program following the program name:<code>
Line 46: Line 41:
 
SQL operations can fail for a multitude of reasons.  For our simple example, our service will catch all SQL and log all SQL exceptions on the server and then throw the exception back to the service client.  It will also log each service invocation.
 
SQL operations can fail for a multitude of reasons.  For our simple example, our service will catch all SQL and log all SQL exceptions on the server and then throw the exception back to the service client.  It will also log each service invocation.
  
Cut and paste these logging function to the service program before the final '''end'' statement:
+
Cut and paste these logging function to the service program before the final '''end''' statement:<code>
 +
    logActive boolean = true;
 +
    activeService string;
 +
   
 +
    private function logEntry(serviceFunction string in)
 +
        activeService = serviceFunction;
 +
        log("Entry:  SQLService, " + serviceFunction);
 +
    end
 +
   
 +
    private function logException(ex sqlException?)
 +
        accumulatedMessage string = "Exception:  SQLService, " + activeService;
 +
        while(ex != null)
 +
            accumulatedMessage = accumulatedMessage + ", SQLSTATE = " +
 +
                    ex.SQLState + ", message = " + ex.message;
 +
            ex = ex.nextException;
 +
        end
 +
        log(accumulatedMessage);
 +
        throw new anyException{message = accumulatedMessage};
 +
    end
 +
   
 +
    private function log(text string in)
 +
        if(logActive)
 +
            sysLib.writeStdOut(text);
 +
        end
 +
    end
 +
</code>
  
 
== Add a payment record ==
 
== Add a payment record ==
Line 55: Line 75:
 
To code the function:
 
To code the function:
  
#In the EGL editor, copy and paste the following lines into <tt>SQLService.egl</tt> before
+
*In the EGL editor, copy and paste the following lines into <tt>SQLService.egl</tt> before
 
the '''end''' statement:<code>
 
the '''end''' statement:<code>
   function addPayment(newPayment paymentRec inOut)
+
   function addPayment(newPayment paymentRec in)
  add newPayment;
+
        logEntry ( "addPayment" ) ;
 +
        try
 +
            add newPayment to ds ;
 +
        onException(ex sqlException)
 +
            logException(ex);
 +
        end
 
   end
 
   end
 
</code>
 
</code>
#Before you continue, you must resolve the reference to
+
*Before you continue, you must resolve the reference to the <tt>paymentRec</tt> Record part. You can automatically create '''import''' statements by using the Organize Imports feature. Right-click any blank area in the editor and click '''EGL Source > Organize Imports'''.  
the <tt>paymentRec</tt> Record part. You can automatically
+
:EGL adds the following statement to the beginning of the file:<code>
create '''import''' statements by using the Organize
+
Imports feature. Right-click any blank area in the editor and click '''EGL Source > Organize
+
Imports'''.
+
EGL adds
+
the following statement to the beginning of the file:<code>
+
 
   import records.paymentRec;
 
   import records.paymentRec;
 
</code>
 
</code>
The
+
:The reference is now resolved. You will use this feature often, whether by selecting the menu item or by pressing Ctrl-Shift-O.
reference is now resolved. You will use this feature often, whether
+
*Save the file (Ctrl-S), and then place your cursor anywhere in the '''add''' statement. Press keys CTRL-1 and select '''Add SQL Statement''' from the popup menu. This feature changes the implicit SQL that underlies the EGL '''add''' statement into embedded code that you can modify:<code>
by selecting the menu item or by pressing Ctrl-Shift-O.
+
   function addPayment(newPayment paymentRec in)
#Save the file (Ctrl-S), and then place your cursor anywhere
+
        logEntry ( "addPayment" ) ;
in the '''add''' statement. Press keys CTRL-1 and select '''Add SQL Statement''' from the popup menu
+
        try
This
+
            add newPayment to ds
feature changes the implicit SQL that underlies the EGL '''add''' statement
+
                with #sql{
into embedded code that you can modify:<code>
+
                        insert into PAYMENT
   add newPayment to ds with
+
                              (CATEGORY, DESCRIPTION, AMOUNT, FIXED_PAYMENT, DUE_DATE,  
      #sql{  
+
                              PAYEE_NAME, PAYEE_ADDRESS1, PAYEE_ADDRESS2)
      insert into PAYMENT
+
                        values
      (CATEGORY, DESCRIPTION, AMOUNT, FIXED_PAYMENT, DUE_DATE,  
+
                              (?, ?, ?, ?, ?, ?, ?, ?)
      PAYEE_NAME, PAYEE_ADDRESS1, PAYEE_ADDRESS2)
+
                  };
      values
+
        onException(ex sqlException)
      (?, ?, ?, ?, ?, ?, ?, ?)
+
            logException(ex);
      } ;
+
        end
</code>
+
  end</code>
 
Notice the PAYMENT_ID field is not included in the record fields added to the table.  The '''@GeneratedValue''' annotation for the field in the record definition tells the EGL SQL builder not to explicitly add the column.
 
Notice the PAYMENT_ID field is not included in the record fields added to the table.  The '''@GeneratedValue''' annotation for the field in the record definition tells the EGL SQL builder not to explicitly add the column.
  
Line 106: Line 126:
 
*In the EGL editor, copy and paste the following lines into <tt>SQLService.egl</tt> before
 
*In the EGL editor, copy and paste the following lines into <tt>SQLService.egl</tt> before
 
the '''end''' statement:<code>
 
the '''end''' statement:<code>
   function getAllPayments() returns (paymentRec[])
+
   function getAllPayments() returns(paymentRec[])
      paymentArray paymentRec[];
+
      payments paymentRec[];
      get paymentArray from ds;
+
      logEntry("getAllPayments");
      return (paymentArray);
+
      try
 +
          get payments from ds;
 +
      onException(ex sqlException)
 +
          logException(ex);
 +
      end
 +
      return(payments);
 
   end
 
   end
 
</code>
 
</code>
The EGL '''get''' statement generates
+
:The EGL '''get''' statement generates an SQL SELECT statement to retrieve a result set. When the target of the '''get''' statement is a dynamic array of records, EGL retrieves all matching rows from the result set and inserts each successive row into the next array element.   
an SQL SELECT statement to retrieve a result set. When the target
+
*As with the '''add''' statement, you may place the cursor anywhere in the statement and press CNTL-1 to see the SQL statement EGL will use to retrieve the rows.  You may again save the default statement and modify it if it does do what you want.
of the '''get''' statement is a dynamic array
+
of records, EGL retrieves all matching rows from the result set and
+
inserts each successive row into the next array element.   
+
*As with the '''statement''', you may place the cursor anywhere in the statement and press CNTL-1 to see the SQL statement EGL will use to retrieve the rows.  You may again save the default statement and modify it if it does do what you want.
+
 
*Save the file.  
 
*Save the file.  
  
Line 126: Line 147:
 
== Replace a record ==
 
== Replace a record ==
  
The <tt>editPayment</tt> function replaces an
+
The <tt>editPayment</tt> function replaces an existing row in the database with an edited version. The default statement replaces all records in the table that have key values equal to the contents of the key fields in the record variable.  Key fields are those fields declared with the '''@Id''' attribute (field '''payment_id''' in our example).
existing row in the database with an edited version. The default statement replaces all records in the table that have key values equal to the contents of the key fields in the record variable.  Key fields are those fields declared with the '''@Id''' attribute (field '''payment_id''' in our example).
+
  
To
+
To code the function:
code the function:
+
  
<ol><li>In the EGL editor, copy and paste the following lines into <tt>SQLService.egl</tt> before
+
*In the EGL editor, copy and paste the following lines into <tt>SQLService.egl</tt> before the logging functions:<code>  
the '''end''' statement:<code>
+
   function editPayment(chgPayment paymentRec in)
   function editPayment(chgPayment paymentRec inOut)
+
      logEntry("editPayment");
      replace chgPayment to ds ;
+
      try
 +
          replace chgPayment to ds;
 +
      onException(ex SQLException)
 +
          logException(ex);
 +
      end
 
   end
 
   end
The EGL '''replace''' statement
+
</code>
generates an SQL UPDATE statement.  
+
The EGL '''replace''' statement generates an SQL UPDATE statement.  
<li>Save the file.
+
*Save the file.  
</ol>
+
  
 
''' Related reference '''<br>
 
''' Related reference '''<br>
Line 148: Line 170:
 
== Delete a record ==
 
== Delete a record ==
  
 
+
The <tt>deletePayment</tt> function deletes the specified record from the table.
 
+
The <tt>deletePayment</tt> function deletes the
+
specified record from the table.
+
  
 
To code the function:
 
To code the function:
  
 
+
*In the EGL editor, copy and paste the following lines into <tt>SQLService.egl</tt> before the '''end''' statement:<code>
<ol><li>In the EGL editor, copy and paste the following lines into <tt>SQLService.egl</tt> before
+
 
the '''end''' statement:  
+
  function deletePayment(delPayment paymentRec in)
 
+
      logEntry("deletePayment");
function deletePayment(delPayment paymentRec inOut)
+
      try
 
+
          delete delPayment from ds;
try
+
      onException(ex SQLException)
  delete delPayment nocursor;
+
          if(ex.SQLState != "02000") // sql state is five digits
 
+
              logException sqlException;
  onException(exception SQLException)
+
          end
      if(SQLLib.sqlData.sqlState != "02000") // sqlState is of type CHAR(5)
+
      end
        throw exception;
+
      end
+
 
   end
 
   end
end
+
</code>
The EGL '''delete''' statement generates
+
*:The EGL '''delete''' statement generates an SQL DELETE statement. If no rows are present, the Derby database returns an SQLState value of "02000", and the EGL runtime code throws an exception that the function ''catches'': that is, processes,
an SQL DELETE statement. If no rows are present, the Derby database
+
returns an SQLState value of "02000", and the EGL runtime code throws
+
an exception that the function ''catches'': that is, processes
+
 
in some onException logic.  
 
in some onException logic.  
  
When a function catches but ignores
+
*:When a function catches but ignores an exception, processing continues without interruption. That rule applies to the preceding logic, when the value of SQLState is "02000". When a function uses the '''throw''' statement to ''throw'' an exception, the exception stays active. That rule also applies to the preceding logic, when the value of SQLState is other than "02000".
an exception, processing continues without interruption. That rule
+
applies to the preceding logic, when the value of SQLState is "02000".
+
When a function uses the '''throw''' statement
+
to ''throw'' an exception, the exception stays active. That
+
rule also applies to the preceding logic, when the value of SQLState
+
is other than "02000".
+
  
At run time, if a service does not handle
+
:*At run time, if a service does not handle an exception, the service requester receives an exception of type ServiceInvocationException. Incidentally, if the service cannot be
an exception, the service requester receives an exception of type
+
ServiceInvocationException. Incidentally, if the service cannot be
+
 
accessed, the requester receives an exception of type ServiceInvocationException
 
accessed, the requester receives an exception of type ServiceInvocationException
 
or ServiceBindingException, depending on the details of the error.
 
or ServiceBindingException, depending on the details of the error.
  
<li>Save the file.
+
*Save the file.  
</ol>
+
  
 
''' Related reference '''<br>
 
''' Related reference '''<br>
Line 200: Line 205:
 
== Create test data ==
 
== Create test data ==
  
 +
The <tt>createDefaultTable</tt> function creates a set of data for testing your completed application.
  
 +
To code the function:
  
The <tt>createDefaultTable</tt> function creates
+
*In the EGL editor, copy and paste the following lines into <tt>SQLService.egl</tt> before
a set of data for testing your completed application.
+
the '''end''' statement:<code> 
 
+
  function createDefaultTable() returns(paymentRec[])
To code
+
      payments paymentRec[];
the function:
+
      logEntry("createDefaultTable");
 
+
      try
 
+
          try
<ol><li>In the EGL editor, copy and paste the following lines into <tt>SQLService.egl</tt> before
+
              execute from ds
the '''end''' statement:  
+
                  with #sql{
 
+
                    delete from PAYMENT
function createDefaultTable() returns (paymentRec[])
+
              };
 
+
        onException(ex SQLException)
  try
+
            if(ex.SQLState != "02000") // sqlState is five digits
      execute #sql{
+
                throw ex;
        delete from PAYMENT
+
            end
      };
+
        end  
 
+
        ispDate date = dateTimeLib.dateFromGregorian(20140405);
  onException(exception SQLException)
+
        addPayment(new paymentRec{category = 1, description = "Apartment"
 
+
              , amount = 880, fixedPayment = yes, dueDate = new date
      if (SQLLib.sqlData.sqlState != "02000") // sqlState is of type CHAR(5)
+
              , payeeName = "A Jones", payeeAddress1 = "100 Jones Dr"
        throw exception;
+
              , payeeAddress2 = "Jonesboro, NC"
      end
+
              });
  end;
+
        addPayment(new paymentRec{category = 2, description = "Groceries"
 
+
              , amount = 450, fixedPayment = no, dueDate = new date
  ispDate DATE = dateTimeLib.dateValueFromGregorian(20110405);
+
              , payeeName = "B Jones", payeeAddress1 = "200 Jones Dr"
  addPayment(new paymentRec{category = 1, description = "Apartment",
+
              , payeeAddress2 = "Jonesboro, NC"
      amount = 880, fixedPayment = YES});
+
          });
addPayment(new paymentRec{category = 2, description = "Groceries",
+
        addPayment(new paymentRec{category = 5, description = "ISP"
      amount = 450, fixedPayment = NO});
+
              , amount = 19.99, fixedPayment = no, dueDate = ispDate
  addPayment(new paymentRec{category = 5, description = "ISP",
+
              , payeeName = "C Jones", payeeAddress1 = "300 Jones Dr"
      amount = 19.99, fixedPayment = YES, dueDate = ispDate });
+
              , payeeAddress2 = "Jonesboro, NC"
  return (getAllPayments());
+
        });
end
+
        payments = getAllPayments();
 
+
          onException(ex anyException)
 +
              logException(ex);
 +
          end
 +
        return(payments);
 +
    end
 +
</code>
 
The code acts as follows:  
 
The code acts as follows:  
  
<ul><li>The EGL '''execute''' statement runs a literal
+
<ul><li>The EGL '''execute''' statement runs a literal SQL statement that deletes all rows from the PAYMENT table.  
SQL statement that deletes all rows from the PAYMENT table.  
+
<li>The <tt>ispDate</tt> variable receives a date value from the '''dateTimeLib.dateValueFromGregorian()''' system function. The content of the variable is then in a format that is appropriate for insertion into the <tt>dueDate</tt> field in the database.  
<li>The <tt>ispDate</tt> variable receives a date value from
+
<li>The <tt>addPayment</tt> function is repeatedly invoked to add new rows to the PAYMENT table.  
the '''dateTimeLib.dateValueFromGregorian()''' system
+
<li>The call to the <tt>getAllPayments</tt> function returns an array of rows that were retrieved from the table.
function. The content of the variable is then in a format that is
+
appropriate for insertion into the <tt>dueDate</tt> field
+
in the database.
+
<li>The <tt>addPayment</tt> function is repeatedly invoked
+
to add new rows to the PAYMENT table.  
+
<li>The call to the <tt>getAllPayments</tt> function returns
+
an array of rows that were retrieved from the table.
+
 
</ul>
 
</ul>
  
<li>Press Ctrl-Shift-F to format the code. If
+
*Press Ctrl-Shift-F to format the code. If you see any red Xs, compare your code with the finished code in [[EDT:Tutorial: RUI With DataBase Lesson 6 Code|Code for PaymentFileMaintenance.egl after lesson 6]]
you see any red Xs, compare your code with the finished code in [[EDT:Tutorial: RUI With DataBase Lesson 6 Code|Code for PaymentFileMaintenance.egl after lesson 6]]
+
*Save and close the file.  
<li>Save and close the file.
+
</ol>
+
  
 
''' Related reference '''<br>
 
''' Related reference '''<br>
Line 271: Line 274:
 
In the next lesson, you will create a widget to hold the table
 
In the next lesson, you will create a widget to hold the table
 
of expense data.
 
of expense data.
 
 
  
 
{| style="float: right"
 
{| style="float: right"
 
|[[EDT:Tutorial: RUI With DataBase Lesson 5|&lt; Previous]] | [[EDT:Tutorial: RUI With DataBase Lesson 7|Next >]]
 
|[[EDT:Tutorial: RUI With DataBase Lesson 5|&lt; Previous]] | [[EDT:Tutorial: RUI With DataBase Lesson 7|Next >]]
 
|}
 
|}
 
  
 
[[Category:EDT]]
 
[[Category:EDT]]

Revision as of 17:34, 29 November 2011

Access a database with EGL Rich UI


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Contents

Lesson 6: Add code for the service functions

In EGL, I/O statements such as add and get access data that resides in different kinds of persistent data storage, from file systems to queues to databases. The coding is similar for the different cases.

In this lesson, you add functions that access rows in a relational database. Add the functions in order, before the final end statement in SQLService.egl.

Create binding to database connection

In Lesson 3, you defined a database connection named Derby'. Use these steps to use the Derby connection from your SQL service.

  1. EGL projects have associated deployment descriptor (.egldd) files. Click on PaymentService in the project explorer and select Properties > EGLDevelopmentDeploymentDescriptor" to see that file PaymentService.egldd was created when you defined project Payment Service. Click on OK to close the properties window.Deployment descriptor property for service project.
  2. Open file PaymentService.egldd with the EGL employment descriptor editor. Open deployment descriptor for service project.
  3. Select the Resource Bindings folder
  4. Add a new resource binding named DerbyResource of binding type SQL database binding.
  5. Select radio button Reference the selected workspace connection below [retrieved at runtime].
  6. Select Derby connection details.
  7. Clink on Finish.Add SQL binding to deployment descriptor.
  8. Close file PaymentServices.egldd

Using an SQL resource binding in service program

Insert a dataSource variable in the service program following the program name:

  package services;
  
  service SQLService
  	ds dataSource? { @Resource { bindingKey="Derby" } } ;   
  end

The syntax directs the service to use the binding named "Derby" defined as a resource in the deployment descriptor file associated with the service project.

Handling SQL exceptions

SQL operations can fail for a multitude of reasons. For our simple example, our service will catch all SQL and log all SQL exceptions on the server and then throw the exception back to the service client. It will also log each service invocation.

Cut and paste these logging function to the service program before the final end statement:

    logActive boolean = true;
    activeService string;
    
    private function logEntry(serviceFunction string in)
        activeService = serviceFunction;
        log("Entry:  SQLService, " + serviceFunction);
    end
    
    private function logException(ex sqlException?)
        accumulatedMessage string = "Exception:  SQLService, " + activeService;
        while(ex != null)
            accumulatedMessage = accumulatedMessage + ", SQLSTATE = " +
                    ex.SQLState + ", message = " + ex.message;
            ex = ex.nextException;
        end
        log(accumulatedMessage);
        throw new anyException{message = accumulatedMessage};
    end
    
    private function log(text string in)
        if(logActive)
            sysLib.writeStdOut(text);
        end
    end

Add a payment record

Include a function to the service program that uses the add statement to insert a new row to the database.

To code the function:

  • In the EGL editor, copy and paste the following lines into SQLService.egl before

the end statement:

  function addPayment(newPayment paymentRec in)
       logEntry ( "addPayment" ) ;
       try
           add newPayment to ds ;
       onException(ex sqlException)
           logException(ex);
       end
  end

  • Before you continue, you must resolve the reference to the paymentRec Record part. You can automatically create import statements by using the Organize Imports feature. Right-click any blank area in the editor and click EGL Source > Organize Imports.
EGL adds the following statement to the beginning of the file:
  import records.paymentRec;

The reference is now resolved. You will use this feature often, whether by selecting the menu item or by pressing Ctrl-Shift-O.
  • Save the file (Ctrl-S), and then place your cursor anywhere in the add statement. Press keys CTRL-1 and select Add SQL Statement from the popup menu. This feature changes the implicit SQL that underlies the EGL add statement into embedded code that you can modify:
  function addPayment(newPayment paymentRec in)
       logEntry ( "addPayment" ) ;
       try
           add newPayment to ds
               with #sql{
                       insert into PAYMENT
                             (CATEGORY, DESCRIPTION, AMOUNT, FIXED_PAYMENT, DUE_DATE, 
                             PAYEE_NAME, PAYEE_ADDRESS1, PAYEE_ADDRESS2)
                       values
                             (?, ?, ?, ?, ?, ?, ?, ?)
                 };
       onException(ex sqlException)
           logException(ex);
       end
  end

Notice the PAYMENT_ID field is not included in the record fields added to the table. The @GeneratedValue annotation for the field in the record definition tells the EGL SQL builder not to explicitly add the column.

Related reference

[../../com.ibm.egl.lr.doc/topics/regl_data_sql_add.html add considerations for SQL] [../../com.ibm.egl.lr.doc/topics/regl_core_function.html Functions] [../../com.ibm.egl.lr.doc/topics/regl_core_import.html import] [../../com.ibm.egl.lr.doc/topics/regl_data_sql_overview.html SQL data access]

Read all database records

The getAllPayments function uses the get statement with an array object to read all of the records from the table and stores them in an array.

To code the function:

  • In the EGL editor, copy and paste the following lines into SQLService.egl before

the end statement:

  function getAllPayments() returns(paymentRec[])
      payments paymentRec[];
      logEntry("getAllPayments");
      try
          get payments from ds;
      onException(ex sqlException)
          logException(ex);
      end
      return(payments);
  end

The EGL get statement generates an SQL SELECT statement to retrieve a result set. When the target of the get statement is a dynamic array of records, EGL retrieves all matching rows from the result set and inserts each successive row into the next array element.
  • As with the add statement, you may place the cursor anywhere in the statement and press CNTL-1 to see the SQL statement EGL will use to retrieve the rows. You may again save the default statement and modify it if it does do what you want.
  • Save the file.

Related reference

[../../com.ibm.egl.lr.doc/topics/regl_data_sql_get.html get considerations for SQL]

Replace a record

The editPayment function replaces an existing row in the database with an edited version. The default statement replaces all records in the table that have key values equal to the contents of the key fields in the record variable. Key fields are those fields declared with the @Id attribute (field payment_id in our example).

To code the function:

  • In the EGL editor, copy and paste the following lines into SQLService.egl before the logging functions:
  function editPayment(chgPayment paymentRec in)
      logEntry("editPayment");
      try
          replace chgPayment to ds;
      onException(ex SQLException)
          logException(ex);
      end
  end

The EGL replace statement generates an SQL UPDATE statement.

  • Save the file.

Related reference

[../../com.ibm.egl.lr.doc/topics/regl_data_sql_replace.html replace considerations for SQL]

Delete a record

The deletePayment function deletes the specified record from the table.

To code the function:

  • In the EGL editor, copy and paste the following lines into SQLService.egl before the end statement:
  function deletePayment(delPayment paymentRec in)
      logEntry("deletePayment");
      try
          delete delPayment from ds;
      onException(ex SQLException)
          if(ex.SQLState != "02000") // sql state is five digits
              logException sqlException;
          end
      end
  end

  • The EGL delete statement generates an SQL DELETE statement. If no rows are present, the Derby database returns an SQLState value of "02000", and the EGL runtime code throws an exception that the function catches: that is, processes,

in some onException logic.

  • When a function catches but ignores an exception, processing continues without interruption. That rule applies to the preceding logic, when the value of SQLState is "02000". When a function uses the throw statement to throw an exception, the exception stays active. That rule also applies to the preceding logic, when the value of SQLState is other than "02000".
  • At run time, if a service does not handle an exception, the service requester receives an exception of type ServiceInvocationException. Incidentally, if the service cannot be

accessed, the requester receives an exception of type ServiceInvocationException or ServiceBindingException, depending on the details of the error.

  • Save the file.

Related reference

[../../com.ibm.egl.lr.doc/topics/regl_data_sql_delete.html delete considerations for SQL] [../../com.ibm.egl.lr.doc/topics/regl_core_xcpt.html Exception handling]

Create test data

The createDefaultTable function creates a set of data for testing your completed application.

To code the function:

  • In the EGL editor, copy and paste the following lines into SQLService.egl before

the end statement:

  function createDefaultTable() returns(paymentRec[])
      payments paymentRec[];
      logEntry("createDefaultTable");
      try
          try
              execute from ds
                 with #sql{
                    delete from PAYMENT
             };
        onException(ex SQLException)
            if(ex.SQLState != "02000")  // sqlState is five digits
                throw ex;
            end
        end 
        ispDate date = dateTimeLib.dateFromGregorian(20140405);
        addPayment(new paymentRec{category = 1, description = "Apartment"
              , amount = 880, fixedPayment = yes, dueDate = new date
              , payeeName = "A Jones", payeeAddress1 = "100 Jones Dr"
              , payeeAddress2 = "Jonesboro, NC"
              });
        addPayment(new paymentRec{category = 2, description = "Groceries"
              , amount = 450, fixedPayment = no, dueDate = new date
              , payeeName = "B Jones", payeeAddress1 = "200 Jones Dr"
              , payeeAddress2 = "Jonesboro, NC"
          });
        addPayment(new paymentRec{category = 5, description = "ISP"
              , amount = 19.99, fixedPayment = no, dueDate = ispDate
              , payeeName = "C Jones", payeeAddress1 = "300 Jones Dr"
              , payeeAddress2 = "Jonesboro, NC"
        });
        payments = getAllPayments();
          onException(ex anyException)
              logException(ex);
          end
        return(payments);
    end

The code acts as follows:

  • The EGL execute statement runs a literal SQL statement that deletes all rows from the PAYMENT table.
  • The ispDate variable receives a date value from the dateTimeLib.dateValueFromGregorian() system function. The content of the variable is then in a format that is appropriate for insertion into the dueDate field in the database.
  • The addPayment function is repeatedly invoked to add new rows to the PAYMENT table.
  • The call to the getAllPayments function returns an array of rows that were retrieved from the table.

Related reference

[../../com.ibm.egl.lr.doc/topics/regl_data_sql_execute.html execute considerations for SQL] [../../com.ibm.egl.lr.doc/topics/regl_core_date_date_value_greg.html dateValueFromGregorian()]

Lesson checkpoint

You learned how to complete the following tasks:

  • Add embedded SQL code to a program and modify that code
  • Automatically create and organize import statements

In the next lesson, you will create a widget to hold the table of expense data.

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