Data Manipulation / Data sources

HOW-TO Create a grand total (with no groups)

If there is a need for grand totals and no grouping in the project, DynamicJasper provides a way to get that.

Grand totals can be located in the header or the footer of the report

DynamicReportBuilder drb = new DynamicReportBuilder();
//ReportBuilder initialization

drb.addGlobalHeaderVariable(columnAmount, ColumnsGroupVariableOperation.SUM);

drb.addGlobalFooterVariable(columnAmount, ColumnsGroupVariableOperation.SUM);

Where the parameters passed are:

• The column to use for the calculation
• The operation to apply (SUM, COUNT, etc)
• The style to use for this total (optional)Refer to GroupsReportTest for a working example.

HOW-TO Create Value Formatter

Value Formatters is the mechanism provided by DJ to decouple the way data is obtained or calculated from the way it is shown.

Value Formatters works like jasper reports patterns, but as they are a java class, complex transformation can be done.

The good thing about Value Formatters is that they don’t mess with the way data is obtained, calculated, or the way you operate with it (i.e: sum), they just work at the time of showing the value.

A simple example with value formatters: Think of a column which represents an amount of time represented in seconds and you want to show it like mm’ ss”, but you also want some totals (you need to sum them). This can be easily done adding a value formatter to an Integer column (which representing seconds). Calculations would be done using real column property, but it will be shown using the formatter.

The big difference between a Custom Expression and a Value Formatter is that the first one aims to replace the column property itself, so the column property class will the declared by the custom expression, and variable operations will be done using custom expression’s output. Value Formatter(s) instead only work at the very moment we shown the value in the report, nothing else, if the column value is obtained through a direct property access or a custom expression it doesn’t affects the value formatter, it just takes the value and returns the needed string to be shown in the report.

Value Formatter(s) may be defined in-line (they are like closures), lets see an example.

AbstractColumn columnaCustomExpression = ColumnBuilder.getNew()
.setCustomExpression(
                return new CustomExpression() {

                        public Object evaluate(Map fields, Map variables, Map parameters) {
                                String state = (String) fields.get("state");
                                String branch = (String) fields.get("branch");
                                String productLine = (String) fields.get("productLine");
                                Integer count = (Integer) variables.get("REPORT_COUNT");
                                return count + ": " +state.toUpperCase() + " / " + branch.toUpperCase() + " / " + productLine;
                        }

                        public String getClassName() {
                                return String.class.getName();
                        }

                }
).build();

HOW-TO Create Custom Expressions

Custom Expressions is the way we provide to let the developer make complex arranging of the data to be displayed in the report such as a concatenation of 2 or more fields from the data source, a math calculation, etc. Custom Expressions classes must implement the ar.com.fdvs.dj.domain.CustomExpression interface, which has a single method: evaluate(Object object) , the parameter is a java.util.Map which contains the elements of the current row.

Custom Expression may be defined in-line (they are like closures) Lets see an example.

AbstractColumn columnaCustomExpression = ColumnBuilder.getNew()
.setCustomExpression(
                return new CustomExpression() {

                        public Object evaluate(Map fields, Map variables, Map parameters) {
                                String state = (String) fields.get("state");
                                String branch = (String) fields.get("branch");
                                String productLine = (String) fields.get("productLine");
                                Integer count = (Integer) variables.get("REPORT_COUNT");
                                return count + ": " +state.toUpperCase() + " / " + branch.toUpperCase() + " / " + productLine;
                        }

                        public String getClassName() {
                                return String.class.getName();
                        }

                }
).build();

As you can see, the keys of the map are the properties defined at the moment of the creation of the columns.

If we need to use fields from the data source that are not directly shown on any column, we must register them like this:

drb.addField("productLine", String.class.getName());
drb.addField("branch", String.class.getName());

The resulting report would be something like this