Hi,
I have the necessity of storing several styling properties for different
types of entities. That entities are identified by a type and a subtype.
The first approach was using a different column for every styling
property (color, stroke, label, etc ...). Some entities needs all the
styling
properties and others just some of them (the number of styling
properties needed is related with the entity type and subtype).
With this approach I have a lot of "noise" in my data model introduced
by the styling properties. Beside, if a new type or subtype of entity
needs another styling property a new column must be added. Some
workarounds exists,
but they don't really solve the original problem (and sometimes they
introduce other problems).
After spend some time thinking about this problem I come to this solution.
I store all the styling properties as a JSON map, i.e. in String that
match this pattern '{"Color":"#FF0000", "Size":10.0}'. With this
approach I can store all the styling properties in a single column in a
flexible way. To make this properties available in SLDs I implement a
new filter function to access the JSON map values. For example to access
the 'Size' value:
(...)
<ogc:Function name='mapper'>
<ogc:PropertyName>json_map_properties</ogc:PropertyName>
<ogc:Literal>Size</ogc:Literal>
<ogc:Literal>5.0</ogc:Literal>
</ogc:Function>
(...)
The first parameter points to the JSON map. The second parameter is the
name
of the property we want access (the map key). The third parameter is
optional and contains the default value.
Does someone have a better approach to this problem ?
(If someone is interested I can contribute the code I write to GeoServer.)
Best regards,
Nuno Oliveira
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