Field update was first introduced in Aspose.Words for .NET 7.0 a few months ago (in fact, it was the last decade – just think about it!). You can read about it in this post: http://www.aspose.com/community/blogs/aspose.words-product-family/archive/2009/09/13/field-update-in-aspose-words-the-killer-feature-of-2009.aspx. Since then, the module we call field engine (or field evaluation engine) was significantly improved. In this post I will tell you what enhancements were made in Aspose.Words for .NET 8.1 we have just released and show what Aspose.Words is now able to do.
- Preserve Formatting in IF Fields
- Bookmark References
- Cell References
Preserve Formatting in IF Fields
IF fields were number one our customers wanted to be updated by the component. That’s why we implemented them from the very beginning, starting with the release where field evaluation engine was first introduced. However, there used to be a limitation: rich contents for TrueText or FalseText were not preserved. It means that if you used something like “**Tr**ue” or “False”, you saw just a plain text “True” or “False” after field update. Moreover, if you inserted a table or a shape into an IF field as an argument, it got lost completely.
We are happy to announce that Aspose.Words for .NET 8.1 does support this feature. You can set anything as TrueText or FalseText value and it will be preserved when evaluating field result. Imagine you have a complex IF field whose TrueText is a table and FalseText is a shape:
Now let’s update fields via Aspose.Words:
Document doc = new Document(“TestPreserveTables.docx”);
(which is a standard code to update fields in the whole document). Open the resulting document, press Alt-F9 to switch to field result mode and you will notice that field result is the table, because it is TrueText for the IF field and the expression is 2 > 1, which is true:
Now let’s change the expression to false:
Run the field update code and open the resulting document. You will notice that field result is the shape, because it is FalseText for the IF field and the expression was changed to 2 < 1, which is false:
Even more, TrueText or FalseText may include paragraph or section breaks, and they will be preserved as well! Let’s make sure:
After updating fields, we see the following (note Word shows section breaks within field result as page breaks for some reason):
Microsoft Word allows to reference bookmarked contents from expressions. That means that you can bookmark two numbers, say 2 and 3, as A and B, respectively, and then reference them from a formula field looking like =A+B:
After the field is updated, its value should be 5. Let’s check if Aspose.Words knows arithmetic. Run the field update code shown above and open the resulting document. Voila:
Too easy, isn’t it? A good pupil should handle more difficult tasks. What about A being a four cells table with a number in each cell and B being an expression that includes a formula field?
Let’s calculate the correct result. For the bookmark A, Word sums up the values in the table, so A = 1 + 2 + 5 + 6 = 14. The average between 2 and 6 is 4, so B = 3 + 4 – 4 = 3. Hence A + B = 14 + 3 = 17.
Run field update code and make sure the result is correct:
Good boy! :)
Another great feature offered by Microsoft Word (and now supported by Aspose.Words) is cell references. When an expression is inside a table, you can reference its cells by using special identifiers, which resembles the way Microsoft Excel works. For example, you can reference a single cell by using an identifier like A1, B4, F8 etc, where the letter means a column and the number means a row, thus A1 referencing the upper left cell in the table:
Updating fields in this document by means of Aspose.Words gives the expected result:
Apart from that, you can designate a whole cell range in your expression. Cell range may serve as an argument of a function that accepts a list of values, i.e. SUM, AVERAGE, MIN, MAX etc. In this case the function subsequently takes the value of each cell in the range.
You can specify an explicit rectangular range like A1:B2, which means the function should work with four cells A1, A2, B1 and B2. You also can omit a letter or a number, instructing the function to take all cells between two columns or two rows, inclusively. For example, A:D means all cells between the columns A and D, including the columns themselves, and 3:3 means all cells in the row 3.
Finally, you can use a special word like ABOVE, BELOW, LEFT or RIGHT to tell the function it should take all cells above, below, to the left or to the right of the cell the expression resides in.
I tried to create a table that demonstrates some of these features:
Running field update via Aspose.Words produces correct results everywhere:
Another trick is that you can reference table cells even from outside the table. To achieve that, you should bookmark the table and precede a cell range serving as a function argument with the name of the bookmark. Let’s bookmark the table from the last example, name the bookmark Table and try to calculate the biggest value in the table using the MAX function placed outside:
Aspose.Words correctly handles what’s going on:
No need to say that Aspose.Words for .NET 8.1 includes a bunch of fixes for the field engine. For example, there used to be a problem with double quotes messed up when IF fields contained merge fields enclosed in double quotes. Also, hyperlinks could lose formatting after update… These and other bugs are now fixed, and as ever, feel free to post an inquiry in our support forums if you encounter any problem.