Developer

Location Property Type

A location property stores a location value returned by a GPS unit that includes the latitude, longitude, dilution, and number of satellites. The location property value can be invalid if the parameters of the property definition are not met. The transaction property location type includes attributes to define these parameters for the location value. The location property may also be set via rule functions that take the latitude and longitude values, converting them to a location value.

When defining this property type there are certain attributes specific to it for transactions and fetches verses objects. The object location property will contain attributes to initialize the value with a latitude, longitude, position dilution, and satellite count.

For a transaction or fetch location property, these same attributes can be set. In addition to these, there are also attributes to specify what is considered the minimum requirements for a valid location value for that property. These attributes set the minimum number of satellites, and the maximo age and position dilution for a location value returned from the GPS unit. If these minimums are not met, the behavior is definable within the property. The value can still be accepted, or it can be rejected.

For transaction and fetch location properties, there also exist the common initialization attributes. These attributes will override the defined latitude, longitude, position dilution, and number of satellites values for the property.

Location Property Attributes

  • Name: Contains the internal unique name for the property definition. This value must be unique among all properties within the same parent definition.
  • Maximum Reading Age: This attribute specifies the maximum reading age in seconds for the value returned by the GPS unit. This reading age represents the last time the unit took a reading. The Maximum Reading Age will dictate the oldest allowable reading for the location property. A location with a reading age older than the one specified in this attribute will be considered an invalid location.
  • Minimum Number of Satellites: This attribute specifies the minimum number of satellites used to calculate the location. There is a minimum of 3 satellites required for any GPS location. A higher minimum may be specified. Note that this differs from the number of satellites the unit can see. This value specifies the number actually used to calculate the location. If this number is less than the minimum number specified the location will be considered invalid.
  • Maximum Position Dilution: This attribute specifies the maximum acceptable position dilution for a location returned to the location property. This is an integral number with a range of values from 1 through 50, inclusive. If the position dilution returned with the location value exceeds this maximum the location will be considered invalid.
  • Accept Invalid Data: This attribute specifies whether or not a location value that does not meet the criteria set for a valid location value to be accepted. If this attribute is set, invalid locations will be accepted. The property will return an invalid location value, which may be checked using the rule function term @IS_VALID_LOCATION.
Transaction and Fetch Attributes - The standard fetch and transaction attributes for initializing the property and targeting object properties are available for the Location property type. The attribute Initial Value includes the normal available settings plus the options listed below, which are specific to the Location type.
  • Current Location After Data Entry: This option specifies the property should be updated to the device’s location after the transaction has been finished and just before it is applied. This value is obtained from the device’s GPS unit.
  • Current Location Before Data Entry: This option specifies the property should be updated to the device’s location before the transaction is displayed to the user. This value is obtained from the device’s GPS unit.