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Attribute

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AssemblyName = ARCQuery
BaseTypes = CompoundKey
ClassNamespace = ARCQuery
ClassType = EntityMethodKey
Description = Key able to call read-only methods defined in the entity class with names like 'TryGet0x007BFieldName0x007D'.0x000D0x000A0x000D0x000ASome common usages of this would be to implement:0x000D0x000A- In a class called 'Customer' with 'FirstName' and 'LastName', a new property 'Name'.0x000D0x000A- In a class called 'OrderLine' with 'Quantity' and 'UnitPrice', a new property 'Sum'.0x000D0x000A0x000D0x000AIn essence this is making an entity class able to describe itself, something which is quite natural in many cases.0x000D0x000A0x000D0x000AThe principle can also be used to simplify querying while still having tables normalized.0x000D0x000AIf for instance address data for 'Customer' objects is normalized into a separate table 'Geography' then one could implement properties on 'Customer' like 'City', 'State', 'Country'.0x000D0x000AThis would enable querying for 'Customer' like0x000D0x000A'SELECT Name, Address, City, State, Country'0x000D0x000Ainstead of the more laborous0x000D0x000A'SELECT Geography.Name, Geography.Address, Geography.City, Geography.State, Geography.Country'0x000D0x000A(see -TryGetForeignField- which is a helper method for this purpose).0x000D0x000A0x000D0x000AImplementations of a few such properties can often significantly reduce the complexity of queries / reduce the need for denormalizing tables in the database.0x000D0x000A0x000D0x000AThe risk of bugs are also reduced since the properties will only be defined in one place, as close as possible to its source propertiesinstead of complex query components being repeated multiple times in a reporting system for instance.0x000D0x000A0x000D0x000AIn addition, memory and disk space is conserved because the returned values are usually ephemeral.0x000D0x000APerformance MAY also be increased as the values are only calculated when needed.0x000D0x000A0x000D0x000AThis class (-EntityMethodKey-) looks for such entity property defining methods through reflection. 0x000D0x000AIt is able to call methods with signatures like either:0x000D0x000A  bool TryGet0x007BKeyName0x007D(out IP retval, out string errorResponse) (see -Simple-)0x000D0x000Aor0x000D0x000A  bool TryGet0x007BKeyName0x007D(IP dataStorage, IK thisKey, out IP retval, out string errorResponse) (see -Complex-)0x000D0x000A0x000D0x000AThe second overload makes the entity class able to query other parts of the system in order to calculate the return value.0x000D0x000A0x000D0x000AThese should be read-only methods / read-only properties, that is, they should not change the state of the entity or the data storage.0x000D0x000A0x000D0x000ANote: 'out IP retval' can be any type assignable to -IP-, so it is recommended to use more strongly typing in the method signature, like 'out PValue0x003CDateTime0x003E retval' for instance.0x000D0x000A0x000D0x000ASee also -NewKey- (creating new keys (new fields) for all entity object types).

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