Incrementing float values in number spinner property fields

Case Manager Client users may encounter issues with number spinner controls when the value in the field is a float type.

Symptoms

Some solutions are designed so that certain number values can be changed within their property field using a number spinner, which can increment the value up or down by a specified amount. However, when the number is a float type, an incremental increase or decrease can have undesirable results. Number spinner property fields can run into issues in several rare situations, such as when:
  • No default value is specified for the property in Case Manager Builder. When a Case Manager Client user increments a number spinner property field up or down with no starting value, then the minimum or maximum value for that float value will be displayed.
  • The value specified for either the large or small increment is a decimal with a specified number of decimal places. Due to certain javascript storage factors, incrementing by decimals can result in numbers that are slightly more or less than the expected value. For example, if the value for a property is meant to contain a US Dollar amount, then the number of significant decimal places is 2, and the number spinner might reasonably be set to increment by 0.01. However, a user incrementing 1.05 up might get a result of 1.060000000997, instead of 1.06 as expected.
  • The value specified for either the large or small increment is not accurate due to rounding errors. For example, if the number spinner is set to increment by 1/3, and the number of decimal places is 2, the value for the increment will be inaccurate since 1/3 cannot be expressed by a decimal with two digits (either 0.33 or 0.34 might be used, neither of which is precisely accurate). Consequently, incrementing the number spinner will begin to cause number errors with each increment. In the example, incrementing up by 1/3 from a starting value of 0.00, using increments of 0.33, will first yield results of 0.33 and then 0.66 after two increments. However, the second increment value of 0.66 is not accurate, as the correct rounded value for 2/3 is 0.67. While this might be temporarily corrected by using a more precise increment (for example, 0.333 instead of 0.33, this will only delay the first inaccurate number until more increments have been applied.

Resolving the problem

There are a number of solutions to these issues that can be applied depending on the situation.
  • You should always define a default value for the property. This will prevent Case Manager Client from using the maximum or minimum value for a float number as the result of a first increment.
  • When a property is to be incremented by a specified decimal value, you should specify the number of decimal places when designing the property in Case Manager Builder. You should also specify that the number should be automatically rounded. When dealing with increments with repeating decimals, choose a meaningful number of decimal places and specify the increment as accurately as possible to avoid rounding errors as best as possible for your solutions needs.
To modify the attributes of a property's number spinner, such as the large and small increments, number of decimal places, and whether the value should be automatically rounded:
  1. Open the solution in Case Manager Builder and click on the property with the number spinner that you want to modify.
  2. Click on the Case Types tab, and click on the desired case type.
  3. Click Views in the left navigation.
  4. Click the Properties Layout tab, and click the desired view.
  5. In the Properties area, click on the property that contains the number spinner field that you want to modify.
  6. Click on the number spinner field. The settings for the number spinner can be found in the Control Settings area.
Parent topic: Troubleshooting Case Manager Client