Filters may evaluate incorrectly when using features and filters that are read in by Format classes

[ahocevar]

Our format classes do not handle data types. So if we read in something like <ogc:value>200</ogc:value>, this will become "200" and not 200. This is true for filters as well as feature attributes. Now if we want to evaluate features against filters, the following will happen:

"200"<"1000"
>>> false

although we would probably have expected to get

200<1000
>>> true

For OGC services, we could rely on WFS DescribeFeatureType to determine if a feature attribute is to be treated as string or as number. For other data sources, there may not be an easy way to do that.

Also, I found out that it would be enough to convert strings either in the filter or in the feature attributes to numbers, because JavaScript seems to auto-convert the string then for the comparison. Since converting strings to numbers for features would slow down our format parsers, it would be sufficient to do this in the Filter format parser (which is currently part of the topp/wfs sandbox).

[ahocevar]

The above patch is against the topp/wfs sandbox.

[ahocevar]

(In [8508]) added numericIf method (references #1874)

[ahocevar]

One possible solution

[ahocevar]

One possible solution. Patch against the topp/wfs sandbox.

[ahocevar]

Actually not only the topp/wfs sandbox is affected by this, but also the current trunk. I am attaching a new patch which is against trunk.

Relevant tests still pass.

[ahocevar]

patch against trunk

[fredj]

The patch looks good but could the numericIf function be moved into the OpenLayers.Number name space ? (lib/OpenLayers/BaseTypes.js)

[ahocevar]

added new patch with tests, moved numericIf function to OpenLayers.String (not OpenLayers.Number as suggested by fredj), and use our isNumeric function in numericIf

[tschaub]

Patch looks good. Tests pass. Please commit.

[ahocevar]

(In [8927]) Cast values containing numbers into Number objects in Filter and SLD format to ensure correct comparison of scale denominators against map scale and filters against features. Introduces a new OpenLayers.String.numericIf function. r=fredj,tschaub (closes #1874)