Fix WMS only layer bug

[ocefpaf]

I guess that the overlay property is not always present.

@BibMartin tiny one to relax after the #266 rebase 😜

PS: The LayerControl seems to be swamping base_layers and overlays. I will take a look into that.

[BibMartin]

The code is ok for me : it can only be better.
But I do you have cases when overlay property is not present ?

[ocefpaf]

This one:

http://nbviewer.ipython.org/gist/ocefpaf/fd50c22dcf9cf1756235

[ocefpaf]

But I do you have cases when overlay property is not present ?

Reading the code closely I think that I am either doing something wrong or the bug is somewhere else.

When I do,

m = folium.Map([40,-100], zoom_start=4)

url = 'http://hfrnet.ucsd.edu/thredds/wms/HFRNet/USEGC/6km/hourly/RTV'

w = folium.WmsTileLayer(url,
                        name='HF Radar',
                        format='image/png',
                        layers='surface_sea_water_velocity',
                        attribution='HFRNet',
                        transparent=True)

w.add_to(m)
m.add_children(folium.LayerControl())
m

the WMS layer should be added as an overlay, but it is being added as a base_layer instead of the underlying openstreetmap layer.

@BibMartin any ideas?

[ocefpaf]

I think I am starting to get your latest changes. (I am slow 😁)

The latest commit adds a missing overlay=True to the WMS layer. Let me know if you think we should get rid of the hasattr(val, 'overlay') or if we should leave it here.

PS: The openstreetmaps is still being added as an overlay instead of the base_layer. I will take a look and fix this in another PR though.

[ocefpaf]

@BibMartin Let me know if this is OK now. I want to take another look at the layers control (making the initial tiles the base_layer and disabling the overlay by default), but I will send those in another PR to avoid confusion.

Update: rebased and good to go.

[BibMartin]

@ocefpaf
It's okay for me.
Squash and go ?!

[ocefpaf]

Done!