Add functions to the service module

Define resources to create, update, and delete customers.

1. Open your service module: myservice.4gl

   Define the following record at the modular level for handling application level errors:

   PUBLIC DEFINE userError RECORD ATTRIBUTES(WSError="User error")
     message STRING
   END RECORD

2. Add a function to insert a customer row in the database (copy and paste the code below)
   In the function's ATTRIBUTES clause the following attributes are set:

   • WSPost – specifies the POST HTTP verb
   • WSPath – specifies the resource endpoint.
   • WSDescription – provides a description of the resource which will be displayed in the generated OpenAPI specification file.
   • WSThrows – is set to handle errors. We trap errors in the TRY/CATCH block. We check the SQLCA record after the execution of the SQL query. We set the SQLERRMESSAGE to the message field of the userError variable and call to SetRestError() to return the message defined in WSThrows for the error.

   In the function's input parameter we provide the new customer's details in the thisCustomer variable of type custinfoType.

   In the function's RETURNS clause, we return the new customer id in the pkey variable.

   PUBLIC FUNCTION createCustomer(
       thisCustomer custinfoType)
       ATTRIBUTES(WSPost,
           WSPath = "/customers",
           WSDescription = "Create a new Customer",
           WSThrows = "400:@userError")
       RETURNS INTEGER
       DEFINE pkey INTEGER
       TRY
           LET thisCustomer.cust_yts = CURRENT
           # cust_num is a serial type, with syntax below, the serial column
           # is not used. See fglcomp -S output for generated INSERT
           INSERT INTO custinfo VALUES thisCustomer.*
           # get the serial number created for the primary key
           LET pkey = sqlca.sqlerrd[2]
       CATCH
           LET userError.message =
               SFMT("SQL error:%1 [%2]", sqlca.sqlcode, SQLERRMESSAGE)
           CALL com.WebServiceEngine.SetRestError(400, userError)
           LET pkey = NULL
       END TRY
       RETURN pkey
   END FUNCTION

3. Create a function to update a customer's details (copy and paste the code below)
   In the function's ATTRIBUTES clause the following attributes are set:

   • WSPut – specifies the PUT HTTP verb.
   • WSPath – specifies the resource endpoint.
   • WSDescription – provides a description of the resource which will be displayed in the generated OpenAPI specification file.
   • WSThrows – is set to handle request errors.
   In the function's input parameter we set the attribute WSParam to specify the customer id.

   PUBLIC FUNCTION updateCustomer(
       resourceId INTEGER ATTRIBUTES(WSParam), thisCustomer custinfoType)
       ATTRIBUTES(WSPut,
           WSPath = "/customers/{resourceId}",
           WSDescription = "Update Customer info",
           WSThrows = "400:@userError")
       RETURNS STRING
       DEFINE ret STRING
       TRY
           LET thisCustomer.cust_yts = CURRENT
           UPDATE custinfo
               SET cust_fname = thisCustomer.cust_fname,
                   cust_lname = thisCustomer.cust_lname,
                   cust_addr = thisCustomer.cust_addr,
                   cust_email = thisCustomer.cust_email,
                   cust_yts = thisCustomer.cust_yts,
                   cust_rate = thisCustomer.cust_rate,
                   cust_comment = thisCustomer.cust_comment
               WHERE cust_num = resourceId
           # sqlca.sqlerrd[3] field gives the number of rows updated.
           IF sqlca.sqlerrd[3] == 1 THEN
               LET ret = SFMT("Updated customer: %1", resourceId)
           ELSE
               LET ret = SFMT("Customer not found: %1", resourceId)
           END IF
       CATCH
           LET userError.message =
               SFMT("SQL error:%1 [%2]", sqlca.sqlcode, SQLERRMESSAGE)
           # 400 is defined by the WSThrows attribute
           CALL com.WebServiceEngine.SetRestError(400, userError)
       END TRY
       RETURN ret
   END FUNCTION

4. Create a function to delete a customer (copy and paste the code below)
   In the function's ATTRIBUTES clause the following attributes are set:

   • WSDelete – specifies the DELETE HTTP verb.
   • WSPath – specifies the resource endpoint.
   • WSDescription – provides a description of the resource which will be displayed in the generated OpenAPI specification file.

   In the function's input parameter we set the attribute WSParam to specify the customer to delete.

   PUBLIC FUNCTION deleteCustomer(
       resourceId INTEGER ATTRIBUTES(WSParam))
       ATTRIBUTES(WSDelete,
           WSPath = "/customers/{resourceId}",
           WSDescription = "Delete a Customer")
       RETURNS STRING
       DEFINE ret STRING
       DELETE FROM custinfo WHERE cust_num = resourceId
       IF sqlca.sqlerrd[3] == 1 THEN
           LET ret = SFMT("Deleted customer id = %1", resourceId)
       ELSE
           LET ret = SFMT("Customer %1 not found ", resourceId)
       END IF
       RETURN ret
   END FUNCTION

5. Create a function to get customer keys (copy and paste the code below)
   In the function's ATTRIBUTES clause the following attributes are set:

   • WSGet – specifies the GET HTTP verb.
   • WSPath – specifies the resource endpoint.
   • WSDescription – provides a description of the resource which will be displayed in the generated OpenAPI specification file.

   In the function's RETURNS clause the array returns a list of customer keys.

   PUBLIC FUNCTION getCustomerRecordKeys()
       ATTRIBUTES(WSGet,
           WSPath = "/customerkeys",
           WSDescription = "Fetches all Customer primary keys.")
       RETURNS(DYNAMIC ARRAY OF INTEGER)
       DEFINE i INTEGER = 1
       DEFINE keys DYNAMIC ARRAY OF INTEGER
       DECLARE customerCurKeys CURSOR FOR
           SELECT cust_num FROM custinfo ORDER BY cust_lname
       FOREACH customerCurKeys INTO keys[i]
           LET i = i + 1
       END FOREACH
       # Remove last element implied by reference in FOREACH loop
       CALL keys.deleteElement(keys.getLength())
       RETURN keys
   END FUNCTION