Although most simple Windchill installations do not require them, webject parameter values must often be taken directly from user input in a web-based form or as a group of unknown size or kind from a data repository. Info*Engine provides a mechanism called “dynamic parameter value substitution” that can be used in the following situations:

The substitution required in a webject is applied once, immediately before a webject is executed. Therefore, to substitute values from a group that is created through the execution of a task, you must execute the task before you execute the webject that contains the substitution expressions. You cannot execute the task from within the webject.

You can use Info*Engine substitution expressions in data attribute values on the param tag used in any webjects.

Info*Engine substitution expressions are always delimited by the characters $( and ). Within these delimiters, specify the group and attributes for which the substitution is made as follows:

where:

To cover the possibility that the evaluation of a substitution expression could return no values, you should include a default for the expression. Specify a default by including the following default attribute on the param tag:

For example, the following param tag sets the default for the ATTRIBUTE parameter to the string "*":

When information must be specified by a user rather than by the designer of a task, the substitution expressions that access the @FORM context group makes this information available within a webject even though the exact value is not known at the time the template or task is being designed.

You can use substitution expressions in any data attribute value on a param tag.

To specify one parameter value as input by a user in a web-based form or on a URL, the parameter value can be similar to the following:

You use @FORM[] in these formats because there is only one element in the @FORM context group. The empty value selector, [], for the form variable is used because there is only one value equated to the variable.

To specify multiple parameter values as input, you include the asterisk (*) as the value selector. To format multiple parameter values correctly, you must also include the delim attribute to identify the comma as the separator in the string that is substituted. For multiple values, the parameter value can be similar to the following:

The asterisk in the value selector, [*], selects all values and concatenates them together into a string using the comma as a separator. The delim attribute tells the webject that multiple values in the data attribute are separated by a comma.

The following variables set up the table format and attributes that are visible to the user. The values for the variables are available in the @FORM context group and can be retrieved from this group.

Also assume that the following Display-Object webject resides in an Info*Engine JSP page and displays an employee list using the variables from the form:

After substitution processing by Info*Engine, the parameters in the webject are as follows:

Assume that the following URL has been submitted to “webServer1”:

Then, the @FORM context group contains the following variables:

Also assume that the following Query-Objects webject resides in the QueryObject.xml task and queries the information system connected to the “jdbc” adapter using the variables from the URL:

After substitution processing by Info*Engine, the parameters in the webject are as follows:

After all processing is completed by Info*Engine, the parameters in the webject are as follows:

When information must come from a VDB group that has been generated, the substitution expressions that access a VDB data group makes this information available within a webject even though the exact value is not known at the time the task is being designed.

You can use substitution expressions in any data attribute value on a param tag.

To specify one parameter value that is substituted from a VDB data group, the parameter value can be similar to the following:

Use grp_name[] in these formats when there is only one element (row) in the group named “grp_name.” Use att_name[] in these formats when there is only one value in the att_name attribute. If the data group has more than one element, you can use grp_name[0] to access the first element in the group and use grp_name[N] to access the last element in the group. To access other elements, you can specify the index of the element inside the brackets. Similarly, you can use 0, N, or other indices inside the brackets to access a specific value in the attribute named by att_name[].

To specify multiple parameter values as input, you include the asterisk (*) as the value selector. To format multiple parameter values correctly, you must also include the delim attribute to identify the comma as the separator in the string that is substituted. For multiple values, the parameter value can be similar to the following:

The asterisk in the value selector, [*], selects all values and concatenates them together into a string using the comma as a separator. The delim attribute tells the webject that multiple values in the data attribute are separated by a comma.

The last set of formats assumes that there is only one element in the named group. If the data group has more than one element, you can use grp_name[0] to access the first element in the group and use grp_name[N] to access the last element in the group. To access other elements, you can specify the index of the element inside the brackets.

For more information, see General Value Substitution Syntax in this topic.

Assume that the following table represents the elements (rows), attributes (column headings) and attribute values (cells in columns) in the “EMP” VDB group:

You can create a new group called “salesEmp” by adding the DEPT attribute column to the “EMP” group using substitution in the following Create-Group webject:

After substitution processing by Info*Engine, the parameters in the webject are as follows:

Executing the Create-Group webject creates the “salesEmp” group that is represented by the following table:

Using the asterisk (*) for the element selector or for the value selector in a substitution expression can return a string containing multiple values. The string can contain:

To understand how these combinations are represented in the string, consider the following graphical representation of a group named “tbl”:

To return a string containing all Y attribute values from element 1 (A and A1), include the following data attribute:

The string returned is:

Notice that the comma separates the values.

To specify a different separator, you must include the valueSeparator attribute. For example, to return a colon-separated list, use the following:

Then, the string returned is:

To return a string containing the first Z attribute value from each element (56 and 77), include the following data attribute:

By default, the string returned is:

Notice that the semicolon separates values from different cells and that there is no value for the third element.

To specify a different separator, you must include the elementSeparator attribute. For example, to return a percent-separated list, use the following:

Then, the string returned is:

To return a string containing all Y attribute values from all elements (A, A1, B, B1, and C), include the following data attribute:

By default, the string returned is:

Notice that the comma separates the values in one cell and the semicolon separates values from different cells.

To specify different separators, you must include the valueSeparator and elementSeparator attributes. For example, to return a string that uses the colon and percent symbols as separators, use the following:

Then, the string returned is:

Using an attribute–value pair for the element selector in a substitution expression provides a way to select an element without knowing the index number of the element.

To understand how the selections works, consider the following graphical representation of a group named “tbl”:

To return a string containing all Y attribute values from the element where X=221, include the following data attribute:

The X attribute value of 221 is located in element number 2, therefore the Y attribute values returned in the string are:

By default, the comma separates the values.