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Web Component Guide

Context Types

See also “Context tab” on page 112.

There are three types of context entries:

•Required

• Optional

• Internal

If a view has only one input other than timeRange or only one required input (and zero

or more optional inputs) it becomes its primary input. The primary input and its priority

defines, whether it appears in data browsers when a node of that type is selected.

Required Context

If the input is marked as required, then it must be provided for the view to operate. You

cannot add a component to a parent unless the parent can provide the required context.

Thus, the parent view must do one of the following:

• Itself have that context as a required input.

• Specify that context by defining it as additional context.

• Specify that element in an instance context of one of its child components.

• Specify the element as an optional or internal input and contain another child that

promises to provide a value for it.

Optional Context

If the input is marked as optional, then the view takes the data if present, otherwise it

has some mechanism for inferring or calculating the data. Often this comes in the form

of a drop down list or selectable table that auto-selects the first element in the data list if

a selected item is not provided. Optional Context items are those inputs that are used if

they are present but are derived in some other way if they are not present. For example:

• A user can define a default value for the input. This default value can take the

form of a query selection or some other mechanism. If the optional input is not

available then the default value is taken.

• Some components such as the Drop-Down List component and Row-Oriented

Table can provide a value if one is not there. For example, if you have a drop

down component with a list of Host objects you can automatically select one and

post it into a Host key using the Flow Context.

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Dell Vizioncore Podręcznik Użytkownika Strona 124