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Selecting Specific Tags
Level 2 API 39
Selecting Specific Tags
TagFilter Interface
TagFilter is an interface type that represents tag read filtering operation. Currently
classes which implement the TagFilter Interface provide two ways to filter tags:
1. Air Protocol Filtering - When specifying a TagFilter as parameter for
Advanced
Reading or Advanced Tag Operations [Deprecated], the filter will be applied at the air
protocol level, i.e. to tags “in the field”. That is, only tags matching the TagFilter
criteria will be returned in an inventory operation or operated (write, lock, etc.) on.
2. Post Inventory Filtering - Objects of type TagFilter provide a match() method
that can be used to check whether a
TagData object matches the TagFilter criteria.
This filtering is not applied to tags “in the field”.
Note
Currently, post inventory filtering with match() can only be used to filter
against a
TagData EPC value.
The TagData class implements the TagFilter interface and TagData objects may be
used as such to match a tag with a specific EPC. The protocol specific classes:
Gen2.Select and ISO180006B.Select, among others, represent the protocol selection
capabilities of their respective protocols and can be used to perform the protocol-specific
filtering operations. Applying a filter of one protocol to an operation of another protocol will
result in an error.
A
MultiFilter object can be used to create more elaborate filters from a list of simpler filters.
MultiFilters are not currently supported by any readers.
Any TagFilter may match more than one tag in an operation; they do not guarantee
uniqueness.
Note
The Mercury4, Mercury5 and Astra readers currently only support TagData
filters. They do not support [Protocol].Select type TagFilters.
MultiFilter
Contains an array of objects that implement the TagFilter Interface. When used as a
TagFilter the array of TagFilters in the MultiFilter object will be applied for tag
selection.