Package com.smartgwt.client.widgets

Class UserFormula

java.lang.Object
com.smartgwt.client.core.JsObject
com.smartgwt.client.core.DataClass
com.smartgwt.client.widgets.UserFormula
All Implemented Interfaces:
HasHandlers
public class UserFormula extends DataClass
An object representing a user-created formula.

Note that the current implementation of formulas simply executes the text as a JavaScript string after making special variables and methods available to the formula. It is safe to allow users to define formulas for themselves (since an end user can always execute whatever JavaScript they want via the browser's built-in developer tools), and is safe to allow formulas to be shared between trusted users. However it would not be safe to allow an untrusted user to create formulas that are shared to other users.

Also, while the current implementation would allow creation of a formula that calls JavaScript functions which are not part of the standard or custom MathFunctions, this behavior should not be relied upon, as future versions of the formula engine may prohibit such calls.

ListGrids additionally allow the formula to be user-modifiable, with the formula created and edited with a FormulaBuilder, either directly or via the ListGrid.canAddFormulaFields behavior.

See Also:

  • Constructor Details

    • UserFormula

      public UserFormula()

    • UserFormula

      public UserFormula(JavaScriptObject jsObj)

    • UserFormula

      public UserFormula(String text)

    • UserFormula

      public UserFormula(String text, Map formulaVars)

  • Method Details

    • getOrCreateRef

      public static UserFormula getOrCreateRef(JavaScriptObject jsObj)

    • setFormulaVars

      public UserFormula setFormulaVars(Map formulaVars)
      Object mapping from variable names to field names. All variable names must be single capital letters (e.g. A). For example, for a formula that should divide the field "population" over the field "area", the formula might be "E/L" and formula vars would be: 
          Map vars = new HashMap();
    vars.put("E", "population");
    vars.put("L", "area");

      When used in the context of grid or detail viewer fields, field names are evaluated against the record.

      When used in the context of forms and editing, this property is not used for formula mapping. Instead, field names are evaluated directly against the current rule context.

      Formulas built by a FormulaBuilder for a ListGrid will normally not define this property and the field names will be used directly, unless useSingleLetterKey is true. However, the Builder may add mapping keys to avoid collisions with registered math functions. When directly using field names in a formula, any mapping keys you add to avoid collisions should contain the string "Field" so that the Smart GWT Framework can detect when single-letter keys are not in use.

      So, for example, if your grid contains a field "max" and you want to use it in a formula, your userFormula might look something like: 

        {
      text: "max(maxField, 1000)",
      formulaVars: {
          maxField: "max"
      }
  }
      .. where the formula also uses the built-in math function max().
      Parameters:
      formulaVars - New formulaVars value. Default value is null
      Returns:
      UserFormula instance, for chaining setter calls

    • getFormulaVars

      public Map getFormulaVars()
      Object mapping from variable names to field names. All variable names must be single capital letters (e.g. A). For example, for a formula that should divide the field "population" over the field "area", the formula might be "E/L" and formula vars would be: 
          Map vars = new HashMap();
    vars.put("E", "population");
    vars.put("L", "area");

      When used in the context of grid or detail viewer fields, field names are evaluated against the record.

      When used in the context of forms and editing, this property is not used for formula mapping. Instead, field names are evaluated directly against the current rule context.

      Formulas built by a FormulaBuilder for a ListGrid will normally not define this property and the field names will be used directly, unless useSingleLetterKey is true. However, the Builder may add mapping keys to avoid collisions with registered math functions. When directly using field names in a formula, any mapping keys you add to avoid collisions should contain the string "Field" so that the Smart GWT Framework can detect when single-letter keys are not in use.

      So, for example, if your grid contains a field "max" and you want to use it in a formula, your userFormula might look something like: 

        {
      text: "max(maxField, 1000)",
      formulaVars: {
          maxField: "max"
      }
  }
      .. where the formula also uses the built-in math function max().
      Returns:
      Current formulaVars value. Default value is null

    • setText

      public UserFormula setText(String text)
      Formula to be evaluated.

      There are two contexts where a UserFormula is used: ListGridField.userFormula / DetailViewerField.userFormula and FormItem.formula or ListGridField.editorFormula. For the grid/detail viewer field formula, all variables used by the formula must be single capital letters (e.g. A). These are derived from field values for the record in question - see formulaVars.

      In addition to these variables, the keyword record may be used to refer directly to the record for which the formula is being evaluated.

      In the context of forms and editing, variables are dot-separated (.) names representing the nested hierarchy path to the desired value within the rule context. No mapping with formulaVars is needed.

      The formula text must be valid JavaScript code and may only call either the built-in math functions or custom functions.

      This attribute is writable only in ListGrids. Applications must call either ListGrid.setUserFormula() or ListGrid.setUserFormulaText() to re-evaluate the formula.

      Parameters:
      text - New text value. Default value is null
      Returns:
      UserFormula instance, for chaining setter calls

    • getText

      public String getText()
      Formula to be evaluated.

      There are two contexts where a UserFormula is used: ListGridField.userFormula / DetailViewerField.userFormula and FormItem.formula or ListGridField.editorFormula. For the grid/detail viewer field formula, all variables used by the formula must be single capital letters (e.g. A). These are derived from field values for the record in question - see formulaVars.

      In addition to these variables, the keyword record may be used to refer directly to the record for which the formula is being evaluated.

      In the context of forms and editing, variables are dot-separated (.) names representing the nested hierarchy path to the desired value within the rule context. No mapping with formulaVars is needed.

      The formula text must be valid JavaScript code and may only call either the built-in math functions or custom functions.

      This attribute is writable only in ListGrids. Applications must call either ListGrid.setUserFormula() or ListGrid.setUserFormulaText() to re-evaluate the formula.

      Returns:
      Current text value. Default value is null