Allow applying dimensions through WMS filter

[arnaud-morvan]

Support dimensions in WMS sources through WMS FILTER parameter.

<source name="layer1" type="wms">
<getmap>
<params>
<LAYERS>layer1</LAYERS>
<FILTER>layer1:"floor" = '{dim:FLOOR}'</FILTER>
</params>
</getmap>
...
</source>

Useful for creating tilesets with dimensions from WMS layers without dimensions (note that QGIS server does not support WMS dimensions for the moment).

[arnaud-morvan]

@tbonfort@jmckenna@rouault : What do you think about this, if accepted I would create a nem PR to update the mapserver documentation.

[arnaud-morvan]

@tbonfort : Hello Thomas, I did not get feedback on this pull request openned 2 months ago, do you think this could be merged ?

[arnaud-morvan]

Hello, how about merging this new feature ?

[jbo-ads]

Sorry for the long delay, hope this is not too late.

Before merging I have some comments:

• Removing duplicate code into _apply_dimensions() is a goot idea. Just take care that rdim->cached_value is now replaced by rdim->requested_value (see issue GetFeatureInfo: dimensions values are not passed to WMS source #212).

• The same loop on dimensions is performed twice. Is it possible to group both computations into only one loop?

• Template with named dimension is handled ({dim:floor}). What about template with all dimensions: {dim} ? Like in cache_sqlite.c for instance (remember to replace rdim->cached_value by rdim->requested_value).

[jbo-ads]

@arnaud-morvan - Is this pull request still relevant?

[arnaud-morvan]

Seems that we do not need this anymore for QGIS which support WMS dimensions now : https://changelog.qgis.org/en/qgis/version/3.10/#wms-dimension
But this could still be interesting when using an external service as source that do not expose the dimensions we would like in mapcache.

[arnaud-morvan]

I put this in my todo list and will try to find some time to spend on this rebase.

[jbo-ads]

Great! Thank you.