Couldn't help but notice that the openmrs team are also engaged in a process of defining generic attributes. And making them the subject of design calls :-)
It might be useful to compare. Two things i pick up from the below is that there seems to be much effort put into attribute types (validated strings, dates etc) though I don't see the coded attributes which we have and (ii) they DO have an interface, Customizable, which applies to all classes which can e extended. Interesting to see these efforts happening at the same time. Cheers Bob ---------- Forwarded message ---------- From: Darius Jazayeri <djazay...@gmail.com> Date: 24 September 2011 21:03 Subject: [OPENMRS-DEV] Current state of attributes To: openmrs-deve...@listserv.iupui.edu Hi All, On our last few design calls we've been working through the generic AttributeType mechanism that we're introducing in 1.9. (see ticket) I wanted to summarize the current state of things. Some of this is in trunk, but some is refactoring I'm doing. I'm especially interested in thoughts about how these classes should be linked together with parameterized types, since I'm not convinced I've gotten that right: interface CustomDatatypeHandler<T> Capable of converting T to/from a String that can be persisted in the varchar column of a database. E.g. a date would be stored as yyyy-mm-dd and an image might be stored as a uri pointing to a PACS system. Also capable of validating T, e.g. so we can use a plain java.util.Date to represent "date-in-past" but limit its possible values. Defines a String "datatypeHandled", e.g. "date", "regex-validated-string") T fromPersistedString(String) String toPersistedString(T) void validate(T) String render(String persistedValue, String view) can be configured with setHandlerConfiguration(String) interface CustomDatatyped holds the definition of a custom datatype (which is handled by a handler of the above interface). For example VisitAttributeType and GlobalProperty (we're able to do typed GPs trivially now) required: String getDatatype() optional: String getPreferredHandlerClassname() if specified, will be handled by this specific CustomDatatypeHandler, otherwise it will be handled by the default handler for this thing's datatype optional: String getHandlerConfig() interface AttributeType<OwningType extends Customizable> extends CustomDatatyped, OpenmrsMetadata for user-defined extensions to core domain objects, which would be handled by adding custom database columns in a less generic system. E.g. VisitAttributeType implements AttributeType<Visit> datatype/handler specified via CustomDatatyped superinterface Integer getMinOccurs() Integer getMaxOccurs() class VisitAttributeType, class LocationAttributeType, class ProviderAttributeType trivial implementations of AttributeType (via BaseAttributeType) interface Customizable<AttrClass extends Attribute> Implemented by domain classes that may be customized by the user via custom attributes. E.g. Visit implements Customizable<VisitAttribute>, Location implements Customizable<LocationAttribute> Has convenience methods for dealing with a collection of attributes, of different types: Collection<AttrClass> getAttributes() //includes voided Collection<AttrClass> getActiveAttributes() //non-voided void addAttribute(AttrClass) void setAttribute(AttrClass) //voids other attributes of the given type interface CustomValue holds a value managed by a CustomDatatypeHandler. E.g. VisitAttribute, GlobalProperty. Any implementation of this has a corresponding CustomDatatyped implementation. "persistedValue" is a String suitable for persisting in a db varchar column; "objectValue" is what you'd want to work with in the API. String getPersistedValue() void setPersistedValue() Object getObjectValue() // don't remember why this isn't <T> void setObjectValue(Object) interface Attribute<OwningType extends Customizable> implements CustomValue, OpenmrsData value corresponding to an AttributeType (which defines its datatype, whether it's required, whether it can repeat, etc), e.g. VisitAttribute corresponds to VisitAttributeType OwningType getOwner() void setOwner(OwningType) AttributeType<OwningType> getAttributeType() class VisitAttribute, class LocationAttribute, class ProviderAttribute trivial implementation of Attribute (via BaseAttribute) class GlobalProperty implements CustomDatatyped, CustomValue this is interesting in that it both defines a custom datatype and stores its value Thoughts welcome... -Darius ________________________________ Click here to unsubscribe from OpenMRS Developers' mailing list _______________________________________________ Mailing list: https://launchpad.net/~dhis2-devs Post to : dhis2-devs@lists.launchpad.net Unsubscribe : https://launchpad.net/~dhis2-devs More help : https://help.launchpad.net/ListHelp
