Prevention of Cartesian Products During Submission

System crash may occur if the calculation result of a Cartesian product is too large. Therefore, a Cartesian product restriction has been added to FineReport to prevent the submission of a row with multiple arrays.

If a row to be submitted contains two or more array-type data records, it will be detected as a Cartesian product. In this case, the system will prevent the data from being submitted, leading to a failed submission.

1. In general reports (namely CPT reports), if Cartesian products exist, a prompt indicating the existence of Cartesian products will appear when you click Submit, as shown in the following figure.

Note:

You are advised to update FineReport with the latest version of the JAR package, which provides location-related prompts when Cartesian products occur.

2. In dashboards (namely FRM reports), if Cartesian products exist, the submission page gives no feedback when you click the Submit button. You can view details in logs.

You can also locate problems through your browser by using Developer Tools.

Loss of Data Filter Relationships

1. The loss of the parent-child cell relationship disrupts the filter relationship between the two cells. The parent cell will no longer be a filter condition for the current cell, which causes  all values of the dataset field to be expanded in the current cell. Consequently, the original 1:1 relationship between the parent and child cells turns into a 1:N relationship.

2. The loss or disruption of the parent-child cell relationship can cause the values in the child cell to either not be expanded at all or be expanded in multiple directions simultaneously, resulting in a Cartesian product.

Occurance of Unnecessary Arrays in the Template

1. Data is grouped by using array functions.

2. The returned value of the drop-down checkbox is of the array type.

3. Values in the table of a dashboard are saved as a list type.

The following figure shows a normal data entry report.

In this case, the default parent-child relationship is used. That is to say, the cells in which values are expanded downward take the left cells as their parent cells. The following four scenarios may result in Cartesian products.

Loss of Filter Relationships Caused by Line Breaks

With a line break, multiple fields in a dataset can be relocated from one row within a data relationship to multiple rows for better display and easy operation.

This will cause Cartesian products because the filter relationship of the first cell in the second row will be lost, causing a N*N submission (Value quantity of Salesman * Value quantity of Sales Volume).

Solution: Set the parent cell of Product Type in the second row to B2 to prevent Cartesian products.

Loss of Filter Relationships Caused by Blank Column Expansion

If expansion is configured for an empty cell, the parent cell of D2 will be changed to C2, causing the loss of the original filter relationship between D2 and B2, as shown in the following figure.

The downward expansion configured for the blank cell in column C cause the cells on the right of column C to lose their filter relationships. Consequently, a Cartesian product will occur due to the N*N submission (Value quantity of Salesman * Value quantity of Sales Volume).

Solution: Set the left parent cell of D2 to B2 to prevent Cartesian products.

Disruption of Filter Relationships Caused by Horizontal Expansion

The horizontal expansion here is a special scenario. If you set Expansion Direction for the cell above a certain field to Horizontal, the filter condition and the parent-child relationship below may be disrupted, causing Cartesian products, as shown in the following figure.

This scenario usually does not happen, but you need to pay attention to it when some columns are hidden.

Solution: Set correct filter and parent-child relationships.

Array Function

If you have grouped data with an array function (for example, the ARRAY function), a Cartesian product will also occur due to the N*N submission, as shown in the following figure.

Solution: Use the JOINARRAY function to output arrays as strings.

Array-Type Value Returned by a Drop-Down Checkbox

If the returned value of a drop-down check box is set to be of the array type, a Cartesian product will also occur due to the N*N submission, as shown in the following figure.

Solution: Change the returned value to be of the string type.

List-Type Values in the Table of a Dashboard

Since no parent-child relationship is limited for data submitted in dashboards (namely FRM reports), the ordinary row data submission (when the cell value of a report block is submitted to a database) will also cause the system to recognize Cartesian products and restrict the submission, as shown in the following figure.

Solution: This data entry method is not recommended because dashboards do not support data entry well inherently.