Tech News Back Issues Issue: 072204
The "Modify Report" Field
As the name implies, the Modify Report field lets us offer our users the ability to modify aspects of a given Report Class. Through this window object, the user can view a Report Class and then select, move, resize and delete existing component objects within that class and select and drag section boundaries without any additional programming on our part. But with a little extra coding effort that involves the properties and methods of this field, we can allow our users to also adjust property values of component objects and sections and even to add new objects and sections to the report.
In fact, the Modify Report field is the core of the "Adhoc Reports" facility of Omnis Studio. Anyone who has used this feature to create or modify an adhoc report will notice that it is not quite the same as the complete Report Editor of the IDE, but it is close. (And we certainly don't want our users messing around to deeply in the classes of the libraries we give them!)
What we will do in this article is to explain and demonstrate what is needed in order to create a Window Class with similar abilities to the Adhoc Report and Report Editor windows. Most of this involves the Modify Report field, but there are a few other practical matters to address as well.
A Word of Warning ... and a Suggested Solution
This brings up an important issue - so before we begin, there is one important thing of which we must remain aware: Any change made to a Report Class using the Modify Report field takes effect immediately. There is no "save"; there is no "undo". Once an operation is performed on the Report Class or one of its component objects, the change is permanent and can only be undone by performing another operation that has the opposite effect.
Given this condition of use, we might want to consider only allowing the user to work with a copy of the Report Class rather than with the original. This then requires finding a way to store these custom Report Classes so that our original library can be replaced (for version updates and such) without destroying the custom reports on which our users have spent so much precious time. Building a separate library to hold just the custom reports is a viable option, but the details of using this technique are beyond the scope of this article (and I find it a bit clumsy as well).
Perhaps a cleaner and more flexible way of handling custom reports is to store their binary class data in the database itself and pull that data into a dummy report intended for this purpose when a custom report is required. Each class has a $classdata property which contains its entire internal definition (all the functional bits other than the class name for our purposes). By creating a File Class or database table to hold records for custom reports that contains this binary information, we can implement both "save" and "revert" operations for each custom report. In fact, we can even tie specific custom reports to different users of the same deployment if that makes sense for our application! After a custom report is used for modification or printing, we then just copy the original (empty) version of the dummy report back into its shell (Report Class) so we can start fresh each time.
We can also use this dummy report as the "report container" for reports we access using our Modify Report field. Rather than changing the $classname property of the field (which we will explore further on in this article), we can simply change the $classdata value of the Report Class already installed in the field. This allows us both to access custom report data from the database and to use existing Report Classes within our library as templates for new custom reports.
For this article, I created an empty Report Class and named it "crashDummy" (in honor of the devastating effects that can occur when we step out of bounds developing techniques like this). I also created a File Class named "customReports" with the following variables in it:
Depending upon the needs of our application, we could also include variables for originator id, creation and modification dates, authorization level for use, etc., but this is sufficient for our needs here.
I also quickly built a simple window for saving the binary data of existing reports into this database. (Actually, I only wanted to get the virgin version of crashDummy into the database so its original pristine state could be retrieved after each use.)
I only bring this up because there are a couple of useful things to know about it. First, the list of Report Classes was build using the $makelist method on the group of Report Classes in the current library:
We can then use the value of the current line of this list selected by the user to get the class data for that report and put it into the record just before we save it:
The classdatasize field is simply used as a read-only reference. It displays the length of the binary data in a calculated, disabled field using the binlength() function, so its calculation ($text property) value is:
I gave the "crashDummy" record an id value of '00000000', making it both easy to remember and easy to pass over when building a list of custom reports from this File. But we're getting away from the main focus of this article...
Building A Report Modification Window
The reason we are given the Modify Report control (or so I assume) is so that we can make our own Report Editor window in our applications so that our users can adjust the Report Classes we give them to suit their individual needs. This is most important for a "vertical market" or "off-the-shelf" application, but it can also be a beneficial feature for a custom application as well.
If our goal is to directly emulate the Report Editor window from the Omnis Studio IDE, we need to create a Window Class with four basic things: the Modify Report field, a toolbar containing controls for that field, a means of modifying property values for selected items within that field (or for the overall report) and a means of selecting tools that allow us to create new component items within the report. Because of the way we have chosen to store the report data, we also need a means of storing and retrieving custom report contents on this window.
Since there isn't enough space in a single article to cover all of this work in minute detail, I will focus on the tools we have at our disposal to manipulate the Modify Report field itself and the Report Class that it displays - plus a few important (or interesting) side trips. If you'd like to see the finished product, attend any of the next Omnis international conferences (OzOmnis 2004, EurOmnis 2004 or AmerOmnis 2005) for my live presentation on this subject.
There are four main collections of controls we want to provide for a Report Editor window:
(We could also subdivide these categories into functional groupings. For example, we might want to separate "Appearance" property tools from "Text" property tools. While this may result in a better user interface, I will lump these all together here in the interest of time. Again, a more complete product will be shown at the conferences.)
The Omnis Programming manual (pp. 136-8) gives us some direction for creating tools for many of these purposes - and it even includes a few examples. In the manual, the creators of Omnis Studio suggest using toolbars to hold controls for changing various aspects of the contents of a Modify Report field. While this may seem unwieldy due to the large number of controls that we would need to handle both the creation of objects and the modification of property values, I must agree that toolbars appear to be more stable currently than other alternatives I have explored. In Mac OS X we have the ability to add drawers (subordinate window instances that pop out any or all of the four sides of a window) to our windows, but I have not been entirely satisfied with my results so far. (Although I have gotten them to work, there are redraw issues and problems stemming from the fact that these windows never "come to the top", so tooltips and other features do not function. Some controls, like tab panes, also appear not to work in this environment - at least in Mac OS X.) On the other hand, doing everything with toolbars on Mac OS X is also unsatisfactory because tools that do not fit along the toolbar become items in a menu that drops down the right edge of the window:
So I have chosen to use toolbars for some things and window fields (entry fields, pushbuttons, checkboxes, etc.) for others on my report modification window - and to make the window wide enough for the toolbar items I have included.
Enough background! What about this Modify Report field?
Modify Report Field Basics
A Modify Report field is a container for a Report Class. It allows the user to perform certain modifications to that class without any programming intervention, but it also allows other kinds of modifications and queries to be performed through various properties, built-in methods and events. There are a few parts or features of this field labeled in the illustration above that are noteworthy. The canvas area is always visible. It is the background on which we view the report class. Depending on ceretain property settings, we may see the report class as a piece of paper with edges that is floating above the canvas or we may only see the report class as a field of white completely covering the canvas. We toggle the showpaper property value to change this view. The Report Class that is displayed in the report class area is the one whose name is given for the classname property value.
To help us judge locations as we drag objects around the report class area, we can also expose a pair of horizontal and vertical rulers in a Modify Report field. The vertical ruler is automatically displayed for the section in which the user is currently working. The visibility of this feature is controlled by the showrulers property of the field. The rulers show either inch or centimeter divisions depending on the setting of the usecms property of Omnis Studio preferences ($prefs.$usecms).
Another aid, especially for complex reports with many subtotal levels, is the connections area. When exposed, this area displays lines connecting section banners that encompass matching subtotal level sections. For example, here we see a line connecting the Page header and Totals sections, thereby encompassing the Page header and Page footer sections (and everything in between). Inside that there is another line connection the Subtotal heading 1 and Page footer banners, thereby encompassing the Subtotal heading 1 and Subtotals level 1 sections. Notice that this line is currently red because a section banner inside it is currently selected. It is showing the current connection.)
The visibility of the connections area is controlled by the showallconns property. In addition, the highlighting of the current connection is controlled by the showcurrconn property. The two work in combination so that the user can see all connections, no connections or only the current connection. At runtime the user can drag the edge of the canvas area to make the connections area wider or narrower. We can use the connswidth property value to read the user's choice in this matter in our code, but we can also use it to set a default width for the connections area in design mode.
By just displaying a Report Class in this field, the user can select any field, background or section object and drag it to a new position. Groups of non-section objects can also be selected. As a group of objects (or a single object) is being dragged, the location of the edges of the bounding box encompassing the selection is shown on the rulers if they are visible. Non-section objects can also be resized by dragging their handles and duplicated by Option/Control-dragging the object(s). Selected objects can be (permanently) deleted by pressing the Backspace or Delete key. In Studio 4, the user can also collapse or expand a section (like in a tree list) by clicking on the triangle at the left end of the section banner. The user can even paste in background pictures from the clipboard!
But we may want to offer our users more power than this, so we must access other features of the field. To do so, we must supply controls so the user can manipulate properties and methods of the Modify Report field.
Manipulating Modify Report Field Properties
Since we decided to use a toolbar to set the basic properties of our Modify Report field, I chose to model the main toolbar for this window after the one used on the Report Editor window of the IDE - with a few enhancements. Here is what I crafted:
I kept the labels short to keep the toolbar from getting too long, but it is simpler than it might appear. From left to right, there are:
a few pushbutton tools for dealing with printing the current report directly from the editor window (including one to Prompt for destination which does not appear on the built-in Report Editor)
Most of these controls contain very simple methods. (For convenience, I have created an instance variable of Item reference type named "targetRef" that points to the Modify Report field in the report editing window.) For example, the $event method for the checkbox that toggles the showpaper property value contains:
The print-related pushbuttons at the left end of this toolbar contain equally simple methods, but they do not directly involve our Modify Report field so we won't dwell on them here. On the other hand, the Sort fields and Page setup pushbuttons contain even simpler methods, but we haven't yet discussed the built-in methods of the Modify Report field that they invoke...
Modify Report Field Methods
Besides the $redraw() method (which is contained by every type of field object we can place on a Window Class), the Modify Report field contains two additional methods. These are $sortfields() and $pagesetup(). When executed, these methods simply open the windows implied by their names for the Report Class currently contained by the Modify Report field. They require no parameters and have no options of any kind. So, for example, the method behind the pushbutton that opens the Sort fields window is:
While the inclusion of the other items to the right of these pushbuttons might imply that there are built-in methods for deleting and inserting lines in a report, this is not the case. These are a bit more complex and will be explained later in this article. The next thing we have to consider is how to select a report for display in this field.
Selecting a Report Class
Of all the properties contained by the Modify Report field, perhaps the most important is classname. This holds the name of the Report Class currently displayed by the field. We can set this to the name of a specific Report Class using the Property Manager if we want to set a "default" Report Class, but we can dynamically change this at runtime to allow the user to work with any existing Report Class. If a Report Class from a different library is required, its name must be qualified with the name of that library. For example, "specialReports.myReport". But that's not how we're going to do it...
Earlier I mentioned setting up a "dummy" Report Class and swapping binary report information into and out of its classdata property as a means of retrieving and storing custom reports to protect them from loss if the library needs to be replaced. The dropdown list on the right end of the toolbar shown above is a first step of this process. It is designed to bring the classdata from another Report Class of our application into the "crashDummy" Report Class, which is pre-installed in the Modify Report field using the classname property. Here is how it works:
The dropdown list field represents an instance variable of the Toolbar Class named "reportList". This list is populated in the $construct method of the dropdown list field using the following code:
(The second line of this method is actually superfluous because we can refer to the column as "reportList.C1", but a label sometimes makes the code easier to read.)
When the user selects a line from this list, the $event method of the dropdown list field puts the new report information into our crashDummy report using this code:
On Mac OS X (and perhaps other platforms) there is one slight anomaly when we switch between a landscape and a portrait report. Although the orientation of the report is transferred as part of the classdata, the redraw does not change the "shape" of the "paper" (if showpaper is set to kTrue). The only thing that will do this is to open the Page setup window and then close it again. It is not the technique that is at fault here, because the same thing happens if we change Report Classes using the classname property of the Modify Report field. While this is not a devastating problem, it is important to be aware of it.
Once we have the proper report in view, it is now time for the user to make modifications. As with other field types, this is facilitated by using event management techniques...
The evSelectionChanged Event
There is only one event of consequence for a Modify Report field. That is the evSelectionChanged event. This event indicates that the user has selected or deselected one or more items within the displayed Report Class. We can use this to perform some important responses to the user's action.
The evSelectionChanged event is accompanied by the pSelectionCount event parameter. This parameter tells us how many objects are currently selected. Since we want to be able to modify both object and overall report properties on this window, pSelectionCount helps us know when to switch between a view of report properties and a view of object properties. If pSelectionCount equals 0, we want to see report properties. Otherwise we want to see fields on our window that can be used to modify the property values for the selected objects.
Because there are so many potential properties to work with, I have chosen to use a paged pane field to display report and object properties separately. Here is a view of some of the report properties:
and here is a view of some of the object properties:
While I have not yet accomodated section properties, this would also be easy to do. (It all just takes time!)
The $event method of the Modify Report field mainly switches between these two pages of the paged pane. The entire method is as follows:
The fields for managing report properties do so directly. That is, the dataname values for these fields directly access the properties of the report class. For example, the repeatfactor field has a dataname value of "$clib.$reports.[rptfld.$classname].$repeatfactor" (where rptfld is an instance variable of Item reference type that points to the Modify Report field). Dealing with object property values is not quite as simple...
Getting and Setting Object Property Values
In order to access the objects that are currently selected in the Modify Report field, we must set the applyselected property of that field to kTrue. This property determines whether notation involving the Modify Report field applies to the field itself (kFalse) or to the selected items within the field (kTrue). When it is set to kTrue, we can use our Item reference to the field as though it were a reference to the group of selected items. This allows us to both get and set property values for those items. We generally set this value to kTrue only for the method being executed, so my preference is to set it in a reversible block like this:
Since we can't have a permanent link to individual items and their properties, we must use instance variables in our report editing window to represent those properties. In some cases where we can use special "picker" pushbuttons, the contents of those fields is used instead of variables. In any case, we have to specifically set those values in our window to reflect the property values of the selected objects. That is the purpose of the $setproperties() method call in the $event method shown above.
For convenience, I use another Item reference variable named "objRef" to point to the group of objects on my window. It is initialized as "$cinst.$objs". An example of setting the value of a "picker" pushbutton is:
and an example of setting a variable value (in this case, an instance variable named "height") is:
We perform exactly the opposite calculation in the $event method of each property mangement field on our window. So to set the textcolor property for the group of selected objects, our pushbutton contains this $event method:
A similar method would be used for a variable-based property field.
But what about properties that are not appropriate for the current selection? Our interface is that much better if users are not tantalized by features they can't use only to find out that such features "don't work". There is a way to avoid this problem...
Disabling Inappropriate Property Fields
Every property has a canassign property. This indicates whether that property can be modified for the current object. Of course, we can only query this property-of-a-property if the (main) property exists in the first place. But both foreground and background report objects have essentially the same set of properties, with different properties disabled for different object types, so this is not much of a problem.
For each property we have chosen to manage, we should disable the field on our window that represents it if the property cannot actually be modified. For example, if textcolor is not an active property of a selected object (like a line), we want the pushbutton used to represent that property to be greyed out (just like in the Property Manager). We can do this by including a line of code like the following in our $setproperties() method:
Only fields representing properties shared (and assignable) by all selected objects are enabled using this technique.
All this is fine for dealing with existing report objects, but what about letting our users create new ones? We can do that too!
Creating New Report Objects
The Modify Report field has another property that can be set to make various object creation tools available for one-time use. This is the tool property. We can use a number of Window and Report objects constants to specify a value for this property and if the user's next action is to draw a rectangular area somewhere on the report area of the Modify Report field, an object of that type will appear. The manual suggests that only background objects can be created in this way, but I have found that kEntry, kPictureobj and even kSection (for Positioning sections) work just fine as well.
All we need is another toolbar to hold all the possible tools. I happen to have one here:
This toolbar is installed next to the one we built earlier. If we make our window wide enough, both can appear without spilling off the right edge of the toolbar.
I have used radio button tools for these both to save space and because only one tool can be selected at a time. I made a separate set for foreground object tools for cosmetic reasons only. The user can still only wield one tool - foreground or background - at any one time.
The $event method for each tool is incredibly simple. Here is an example for the text tool:
Upon creation, an object is automatically selected and so it also automatically triggers the evSelectionChanged event. With the infrastructure we have already developed, we see that the property management pane of our paged pane automatically opens and the fields representing the available properties of our newly created object await our input. In our single window we have now created the near-equivalent functionality to the Report Editor, Property Manager and Component Store! What more could we want?!
Adding and Removing Lines
Certainly there are many things still lacking from the combination of the three IDE tools mentioned in the last section, but there is one more issue to address: the insertion and deletion of lines. The Report Editor window allows us to select one or more lines and then to either insert that number of lines (above the top selected line) or delete the selected ones (and all objects that lie upon them). Interestingly, the Adhoc Report window, which is based upon the Modify Report field, does not allow us to select lines and show them highlighted. I certainly haven't discovered how to do that.
What I have discovered is a technique for inserting or deleting the line directly above the line on which the currently selected object resides. If more than one object is selected, they must lie on the same line in order for this technique to work. While this will require some user training, the concept should not be too difficult. Here is how it works:
Each object in a report, including each section banner, has a lineno property that contains the line number within the Report Class on which it lies. We can use notation to modify the value of this property to move an object to a different line. The trick is, we have to make room in the report for a new line first before we can "insert" one. We do this by increasing the lineno value of the End of report section before changing the lineno value for any other object. So we are actually only adding a line to the bottom of the report and then moving all the objects with line number values greater than or equal to the currently selected object down a line.
Of course, this assumes that we have captured the lineno value of the selected object. We can do this by adding the following line of code to our $setproperties() method:
The variable linenumber is an instance variable of our window and it has the Long integer datatype. Using this, we can then put the following code in the $event method of the Insert line pushbutton in our toolbar:
The "deletion" of a line is performed in a similar way, but we make sure that we move the End of report section up a line (the only action that actually removes a line from the Report Class) after all other objects have been relocated. Here is that code:
The ability to actually see the line highlighted that is the basis for the insertion or deletion would certainly be nice, but this still serves the purpose. I have not included code that would remove items that line on the line to be "deleted", but I leave that for you as an extra credit exercise. I have also not addressed the creation of new customReport records or the retrieval of existing ones, but I assume you know how to do that...
Until Next Time...
I think that's enough for now. I hope this proves to be of some use to you. I look forward to seeing all of you who will attend the OzOmnis conference in August!
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