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Task 3 - Specifying Screen Field Details After you have created the image of a data screen with the screen painter, you usually need to specify some further details for the data fields on the screen. These details include automatic data movement, field-associated functions, and some special field processing indicators. For two fields on your data screen, some default values will already be created based on the field specification you used to define the field. In most of these cases you will only need to add the automatic data movement specifications. Menu Path To access the screen field details screen from the main menu: 1. Select the Screens option. 2. Choose Details. Screen Description This screen allows you to complete the definition of each input or display field on an application data screen.Screen Field Details Screen First you must enter the name of the screen, and then step through the fields on the application data screen completing their respective details. The complete screen field details screen is used for each field on your application screen. To enter the field values: Field Entry Explanation --------------------------------------------------------------------------------------- Screen product_scrn The name of the data screen that you are defining field details for. Table 3-0. (cont.) Field Entry Explanation --------------------------------------------------------------------------------------- Sequence Number Accept the default. The field number, defined by the sequence of data fields on your data screen. The field sequence for this screen is set automatically from top left to bottom right. This sequence of fields and allocation of field numbers is determined by the Automatic Numbering flag on the screen header screen. When you press the Return key, the details already recorded for this field are displayed at the bottom of the screen. The dictionary specification details have been automatically transferred to this screen, and many of the fields contain a default value. Field Spec. Name Accept the default. This field defaults to the dictionary field specification name used to define the attributes of this screen field in the screen painter. Blanking out this field changes the last nine fields on the field details screen to input fields. These fields cannot be changed when a link to the dictionary exists through a field specification name. If you have blanked out the field specification name, re-enter the name product_no to protect the screen field specification again. Primary F-product_no.product This entry specifies that when the cursor is moved to this screen field, the current contents of the field product_no from the file buffer product are moved to the screen buffer and then displayed. On completion of data entry, the new contents of the screen field are moved to the file buffer. (Refer to "Entry Notes" section in this lesson.) To enter behavioral characteristics fields: The next six fields define the way the field behaves on the screen. This is not dependent upon any data type, format, or validation specifications. Field Entry Explanation --------------------------------------------------------------------------------------- Input/Display Accept the default. This indicates whether this data field is an input field (I), or a display field (D). It enables you to override the setting you specified in the screen painter. Required Field Accept the default. Indicates whether this field must be non-blank for alphanumeric, or non-zero for numeric fields, for the field value to be accepted. When the user attempts to move off a required field that has been left blank, the field is highlighted and the cursor remains on it. The user can move back to a field with a lower sequence number, or enter data into the current field. The user cannot commit the screen with the Commit Data function key while a required field remains blank. Help Name Accept the default. This is the name of the help screen that is called if the user presses the Help function key while the cursor is on this field. If you have defined a help screen name for this field specification in the dictionary, that name is automatically transferred to this field. If you haven't specified a help screen name, HP ALLBASE/4GL creates a default help screen name with the same name as the field. You can change the help screen name here without affecting the dictionary specification. Table 3-0. (cont.) Field Entry Explanation --------------------------------------------------------------------------------------- Clear on COMMIT Accept the default. This field works in conjunction with the Clear Fields on COMMIT setting specified on the screen header for this screen. The relationship is an OR relationship. That is, if the setting for either is Y, the field is cleared. Only if both are set to N will the field not be cleared. Include in SHOW Accept the default. This specifies whether the field should be manipulated when it is referred to from a logic block SHOW command. With some fields, you may want to ensure that the only time anything is ever done to them is when an explicit reference is made to them. The SHOW command is used in HP ALLBASE/4GL logic to redisplay data in a screen field. You will learn about the SHOW command in a later lesson. Automatic Flow to Accept the default. So far, all the fields that you have used Next require you to press the Return key to signal that the field entry is complete. In the same way, the fields you define for an application screen normally require the user to press the Return key to complete a field entry. Under some operating systems, setting the Auto Flow to Next field to Y causes HP ALLBASE/4GL to generate an implicit Return when the user fills the field. Although displayed on this screen, that facility is not available under the MPE/iX operating system. To enter function specification fields: You can associate a logic function with each screen field. The next four fields specify how the function for this field is executed. This function enables you to perform some data manipulation or validation when data is displayed in the field, or entered into the field. The field function you are naming here will read the product file for a record with a key value matching the value entered by the user. Field Entry Explanation --------------------------------------------------------------------------------------- Function product_key_read This is the name of the function to be associated with this field. If you leave this field blank, entry into the next three fields is not possible. Prior/After/Both A This entry specifies when the function is executed. There are three available options. P indicates that the function is executed prior to data entry, when the user moves the cursor onto the field. A indicates that the function is executed after the completion of data entry for the field; this is only valid for input fields. B indicates that the function is executed both prior to and after data entry. Table 3-0. (cont.) Field Entry Explanation --------------------------------------------------------------------------------------- Perform Function on Accept the default. This field relates to the behavior of the SHOW field under a SHOW command from a logic block. At times the function may perform some data formatting or extraction that is essential for the correct data to be displayed. In this case, the function needs to be executed when the field is displayed under control of a SHOW command. After Function if Accept the default. This field only applies to non-required Blank screen fields. It indicates whether the function is executed even if the screen field has been left blank. You may have noticed that only one function can be called from the field, yet the function can be called at three distinctly different times; prior, after, or on SHOW. HP ALLBASE/4GL has two switches (*ENTERED and *SHOWING) that you can test in the function to determine when the function is being executed. This allows you to use the one function to perform three different operations, depending on the processing stage at which the function is executed. To enter validation and format specification fields: The bottom nine fields on the screen are a copy of the same fields from the dictionary field specification screen. If you have entered a field specification name in the Field Spec. Name field at the top of this screen, you cannot change any of this group of fields. You can only enter local field definitions if there is no field specification name associated with the application screen field. The fields are not described here as they have exactly the same meaning as their counterparts in the field specification screen. To complete the Product Number screen: 1. Once you have completed all of the details for this particular screen field, press the Commit Data function key. When you press this key, the cursor returns to the Sequence Number field. The details for the next field on the application screen are then displayed, enabling you to enter the remaining details. As you go through the screen fields, HP ALLBASE/4GL creates a primary data movement identifier automatically. This data movement identifier consists of the field specification name for the current field and the file record specified for the first field on the screen. To complete the remaining screen field details: Now you are ready to complete the screen field details for the rest of the training screen. * Enter the details listed. Only those fields that require an entry other than the default are listed here. * After entering the details for each field, press the Commit Data function key. * If you make an error in a particular field of the screen, you can display its details by entering its sequence number and pressing the Return key. The field details are then displayed so you can modify them, and commit them again. The following entries are required to complete the screen field details. Description Sequence Number 2 Primary F-description.product Supplier Number Sequence Number 3 Field Spec. Name supplier_no Primary F-supplier_no.product When you defined the supplier number field in the screen painter, you didn't use the dictionary field specification name method. For this reason, a default name is not displayed with the rest of the field details. When you enter the name supplier_no, the fields at the base of the screen become display fields. Lead Time Sequence Number 4 Field Spec. Name lead_time Primary F-lead_time.product Required Field N As with the previous field, you didn't use the dictionary field specification name method to define this field in the screen painter; therefore, no default name was displayed. You have now completed the definition of the fields for this screen. As with a record layout, you must generate the screen before it can be used. The "Entry Notes" section that follows provides additional information for some of the fields. If you wish, skip this section and continue on to "Task 4 - Generating the Data Screen." Entry Notes Data Movement The Primary, Default and Other fields define the automatic data movement that occurs as the user moves through the fields on the application screen. The three types of data movement are: Primary When HP ALLBASE/4GL displays a screen field, it moves the contents of the primary data movement field to the screen and displays the field contents. For an input field, HP ALLBASE/4GL moves the contents of the screen field to the primary data movement field after the user completes data entry for the screen field. Default If the screen field is blank, HP ALLBASE/4GL moves the contents of the default field to the screen and then displays its contents. If the screen field is not blank, no action takes place. Other For input fields, HP ALLBASE/4GL moves the contents of the screen field to the other data movement fields when the user completes data entry for the field. Each input field can have up to three other data movement fields.
NOTE You cannot specify both a primary and a default data movement field. They are mutually exclusive. A field can only have one source for its data, however, you can combine either of these "source" movement fields with up to three Other data movement specifiers.
The fields you name in these automatic movement specifiers can be any of the following: * A file record field reference. * A screen field reference. * A scratch-pad field reference. * A variable. * A numeric or alphanumeric constant (default data movement field only).
NOTE The file record field specifier consists of three components. The prefix F- indicates that this is a file buffer field reference. Next, the field name product_no indicates the field to be used, and the file name product specifies the file buffer to be used. These last two terms are separated by a single period (. ). Refer to the HP ALLBASE/4GL Developer Reference Manual for further information on naming and referencing rules.
As the Primary and Default move specifiers are mutually exclusive (you can only move data into the screen field from one of these sources), HP ALLBASE/4GL skips over the Default move field. If you wanted to alter this field, you would need to delete the Primary move specifier, and then specify the Default move field. No Other move fields are to be entered in this example. When you leave the first Other move field blank, HP ALLBASE/4GL skips over the next two.
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