Unbold frontmatter chapter names in table of contents [duplicate]

Question

According to the thesis guidelines set out by my university, the Chapter names in the table of contents must be bold. But all sections in the prefatory sections must be normal font (unbold) in the table of contents.

How can I unbold the table of contents entries in just the frontmatter?

\documentclass{book}
\begin{document}
\frontmatter
\chapter{Abstract}
The ``Abstract'' entry (and entries for other frontmatter chapters) in the table of contents should be unbolded.
\tableofcontents
\mainmatter
\chapter{Chapter name}
But the mainmatter chapters should still be bold in TOC.
\end{document}

Answer 1

I'm not sure this is wise....

Caveat emptor....

\documentclass{book}
\begin{document}
\frontmatter
\let\bforigdefault\bfdefault
\addtocontents{toc}{\let\string\bfdefault\string\mddefault}
\chapter{Abstract}
The ``Abstract'' entry (and entries for other frontmatter chapters) in the table of contents should be unbolded.
\tableofcontents
\mainmatter
\addtocontents{toc}{\let\string\bfdefault\string\bforigdefault}
\chapter{Chapter name}
But the mainmatter chapters should still be bold in TOC.
\end{document}