How to create a fancy tooltip in HTML reports with PRD

When you create reports that are mainly used on the web, you probably want to enrich your reports with some basic interactivity. Charts need links and tooltips on their data, drill downs need to be defined and hopefully the information overload of ordinary reports gets reduced via fancy images, hidden sections that only show up on demand and other techniques.

The most basic way of creating a annotation on a report is to provide tooltips. Sadly the HTML creators were weird scientists who were used to long and boring lists of footnotes instead of in-lined annotations.

Today I am showing you how to create fancy, JavaScript based tooltips onto a report. You can adapt the same technique to create other interactive elements, including Google Maps integrated reports or other Web-2.0 mash-ups.

Rich-Text tooltips: The idea

The tool-tip system I am integrating is based on the blog posting written by Michael Leigeber, a web designer and .NET developer who runs the Leigeber Web Development Blog.

The tool-tips behaviour is defined in a central script that gets included in the report’s generated HTML output. To include the script, we simply copy the whole raw HTML/javascript into the report attribute “html::append-body”. When executing the report, the contents of this attribute are copied into the HTML file before the first table is rendered.

If you want to know how the tooltip script works, please refer to Michael Leigeber’s blog posting.

On each element that we define, we can now define the tooltip as HTML text on the “onmouseover” attribute.

tooltip.show('Testing  123 ', 200);

The tooltip gets hidden when the mouse leaves the element via the “onmouseout” attribute.

tooltip.hide()

The first parameter in the “show” method call is used as ‘innerHTML’ on the generated tooltip element. So you instead of just plain text, you can include any HTML content you like, including images, tables or animations.

Dynamic Tooltips: Show me my data in the tooltip

We all agree that static tooltips are rather boring. A tooltip, well-placed can mean all the difference between a information-overloaded report and a report that shows the exactly the right information you need at exactly the right time. Show the main sales numbers, and move the detail content into the tooltip.

In Pentaho Reporting, most attributes and styles can either contain a static value or can be computed at runtime via an expression or formula. When you see a green plus on the last column of either the style or attribute table, then you will be able to add a calculation for that property.

To make the tooltip show your own data, you will need to make the first parameter of the tooltip.show(..) function call dynamic. The “onmouseover” property expects a string that is valid JavaScript. The reporting engine does not interpret this string at all, it just passes it into the resulting HTML document and lets the browser decide what to do with it.

So all we need to do, is to compute a JavaScript text that contains our data:

="tooltip.show('" & [myfield] & "');"

But careful. If myfield contains any character with special meaning in JavaScript, like quotes, your script is not going to work. To make it work we will need some proper quoting to turn the text into proper JavaScript code.

The Pentaho Reporting Engine offers the “QUOTETEXT” function for this purpose. This function takes two parameter. The first parameter is the text you want to quote, and the second parameter is a constant telling how you want to quote the text: “javascript”, “xml”, “html”, “formula-string” or “formula-reference”.

For now we will need two sets of qouting, “javascript” and “html” as our quoting, and alter the formula above to read:

="tooltip.show('" & QUOTETEXT(QUOTETEXT([myfield];"html");"javascript") & "');"

The inner QUOTETEXT ensures that the text given in [myfield] is proper HTML and that all special HTML characters are encoded properly. So ‘>’ gets converted into >, ‘<' into < and so on. The outer QUOTEXT function then ensures that the resulting text is also proper JavaScript code. It encodes all single and double quote characters and all newlines, tabs and so on into their properly encoded JavaScript counter parts.

This is already a working tooltip, even though it is a bit primitive. Earlier on I said, you can use HTML text as tooltip. So lets do a bit of HTML magic here. Again, text in HTML needs to be encoded properly as well.

="tooltip.show('" & QUOTETEXT("

" & QUOTETEXT([PRODUCTNAME];"html") & "


" & QUOTETEXT([PRODUCTDESCRIPTION];"html") & "

";"javascript") & "');"

This produces a tooltip that prints the product code from the steel-wheels example and the product description divided by a horizontal line.

You can grab a sample report for Pentaho Reporting 3.8.0-GA:
fancy-html-tooltip.prpt

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