MagicDraw 19.0 LTR SP1 Documentation

Metachain operation is one of the operation types used to specify criteria for querying models. Use the Metachain Navigation operation type when specifying indirect (multi-level) relations between elements through the chains of properties.


Metachains allow you to search for indirectly related elements, although they do not support loops and recursive relations.


How to specify a Metachain Navigation as criterion

  1. Click Metachain Navigation on the left side of the dialog box.

  2. Change the name of the operation, if needed.
  3. Click  to set a style that represents the specified metachain navigation symbol.

  4. Click the Insert button to create a new step of the metachain. A new row is added to the list in which you need to specify a metaclass or stereotype and a property for a metachain navigation as shown in the following table:



    Either a metaclass or a stereotype of a metachain step (see Figure 2). The first step, when created, already has a metaclass or a stereotype selected by default. This value is the context element type. The default metaclass or stereotype of the first step can be changed. The second step and all further steps are more specific: the values suggested for selection are limited according to the values selected in the first step, since you will not be able to add a new step until the current step is not specified.

    PropertyA property of the selected metaclass or stereotype.


  5. Repeat the previous step to create as many steps of the metachain as you need for specifying the criteria.


    To remove a step from the metachain, click the Remove button.




Manipulations in Expert Mode

The Expert mode allows you to change the Contextual element of a Metachain Navigation operation, and to create a new operation in which the result of the Metachain Navigation operation is used as an argument.


How to change the Contextual element of a Metachain Navigation criterion

  1. On the left side of the dialog box, expand the Metachain Navigation criterion and select the Context parameter.
  2. Click the Reset button on the Context specification panel.

    The value of the Context parameter becomes null. 
  3. Select a new context from the list of operations and element types.


    To restore the original context, expand the Other group, and click Contextual Variable.

How to use the expression of a Metachain Navigation operation as a parameter of another operation

  1. On the left side of the dialog box, Click Metachain Navigation.
  2. On the criteria specification panel, click the Use as button, and select the appropriate command.


  3. Specify other parameters of the new operation.


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