[Tex/LaTex] Suppress *some* URLs with biblatex nature.bbx class

biblatexurls

I am using a Nature biblatex style with bibtex to typeset bibliography and would like to suppress URLs from appearing in the "paper" entry types (like books, journal articles and proceedings). If I use url=none, URLs are suppressed everywhere, including the online resources. I need to avoid it. Is there a way?

Update
I use Mendeley to manage bibliography. These are two @book examples from the bib-file: 

@book{SnyderLove1983,
  address = {London},
  author = {Snyder, Allan and Love, John},
  publisher = {Chapman \& Hall},
  title = {{Optical waveguide theory}},
  url = {http://books.google.com/books?id=gIQB\_hzB0SMC},
  year = {1983}
}

@book{Agrawal01,
  author = {Agrawal, Govind P.},
  edition = {3rd},
  pages = {467},
  publisher = {Academic Press},
  series = {Optics and Photonics},
  title = {{Nonlinear Fiber Optics}},
  url = {http://www.elsevierdirect.com/product.jsp?isbn=9780120451432},
  year = {2001}
}

This is @inproceedings:

@inproceedings{Liao2011,
  author = {Liao, Changrui and Wang, Dongming and He, Xiaoying and Yang, Minwei},
  booktitle = {Proceedings of SPIE},
  doi = {10.1117/12.885826},
  number = {13},
  pages = {77534I--77534I--4},
  title = {{Twisted optical microfiber for refractive index sensing}},
  url = {http://link.aip.org/link/?PSISDG/7753/77534I/1 http://link.aip.org/link/PSISDG/v7753/i1/p77534I/s1\&Agg=doi},
  volume = {23},
  year = {2011}
}

In the @inproceedings record, Mendeley has concatenated two URLs in the bib-file. A bug, clearly.

Best Answer

This is difficult to handle within a style as it depends on how people store data in their database. (Different users will have different ideas about which types should and should not include a URL.) However, within a document it should be easy enough to handle using biblatex's abilities to access the data model. For example, something like

\AtEveryBibitem{%
  \ifentrytype{book}
    {\clearfield{url}}
    {}%
}

will clear the URL field for all books. Using a boolean expression, this can then be extended for multiple entry types

\AtEveryBibitem{%
  \ifboolexpr
    {
      test { \ifentrytype{book} }
      or
      test { \ifentrytype{inbook} }
      or
      test { \ifentrytype{inproceedings} }
    }
    {\clearfield{url}}
    {}%
}
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