Biblatex: Citing complex nested unpublished sources

Question

I am writing a genealogical document and am working on the bibliography.

Some of the sources I have used are encapsulated inside "bundles". An example:

Name of jurisdiction, box no. 2 containing cases 100 to 199, stored at National Archive, containing:

• case no. 123, containing:
  • copy of interrogation transcript, dated so & so
  • statement from John Doe, dated etc
  • birth certificate of Jane Doe, dated & attested by pastor Name
  • police report, dated & signed etc.
  • other items, etc
• case no. 124, containing:
  • other documents

Are there any biblatex styles or similar for such sources? I would prefer to keep each sub-source inside the "super-source" but still be able to cite each of them separately.

---

Update: As per comments below, I have created a custom entry type that has among other things a "contains" field:

\DeclareDatamodelFields[type=list, datatype=literal]{
    contains}

I can then populate that in my .bib file with contains = {ITEM1 and ITEM2}. However, I'd prefer to use comma-separated lists. As far as I can tell, this is done with [type=field, format=xsv] but using that causes biber to exit right after Found BibTeX data source without writing a .bbl file.

I've tried googling for working example, but no luck...

---

Update: Smallest working example I could make:

\documentclass{article}

\usepackage{filecontents}
\usepackage{csquotes}

\begin{filecontents}{\jobname.bib}
@archivalsource{Test,
    title = {Test Source},
    contains = {ITEM1 and ITEM2}}

@archivalitem{ITEM1,
    title = {Transcript},
    author = {J. Doe}}

@archivalitem{ITEM2,
    title = {Report},
    author = {J. Moe}}
\end{filecontents}

\begin{filecontents}{archival.dbx}
\DeclareDatamodelFields[type=list, datatype=literal]{
    contains}
\DeclareDatamodelEntryfields[archivalsource]{
    title,
    contains}
\DeclareDatamodelEntryfields[archivalitem]{
    author,
    title}
\end{filecontents}

\usepackage[datamodel=archival, backend=biber]{biblatex}

\addbibresource{\jobname.bib}

\DeclareBibliographyDriver{archivalitem}{%
  \usebibmacro{bibindex}%
  \usebibmacro{begentry}%
  \printnames{author} - %
  \printfield{title}%
  \usebibmacro{finentry}}

\DeclareListFormat{contains}{
  \item \entrydata{#1}{\usedriver{}{\thefield{entrytype}}}
}

\DeclareBibliographyDriver{archivalsource}{%
  \usebibmacro{bibindex}%
  \usebibmacro{begentry}%
  \printfield{title}. %
  \printtext{Contains:}%
  \begin{enumerate}%
  \printlist{contains}%
  \end{enumerate}%
  \iflistundef{contains}{\finentry}{}}

\begin{document}

Blah blah.\cite{Test}

\nocite{ITEM1, ITEM2} % otherwise they won't show up
\printbibliography[type=archivalsource]

\end{document}

Answer 1

Alright I got it working with the help in the comments. The code below renders as:

\documentclass{article}

\usepackage{filecontents}
\usepackage{csquotes}

\begin{filecontents}{\jobname.bib}
@archivalsource{Test,
    title = {Test Source},
    contains = {ITEM1, ITEM2}}

@archivalitem{ITEM1,
    title = {Transcript},
    author = {J. Doe}}

@archivalitem{ITEM2,
    title = {Report},
    author = {J. Moe}}
\end{filecontents}

\begin{filecontents}{archival.dbx}
\DeclareDatamodelFields[type=field, format=xsv, datatype=entrykey]{
    contains}
\DeclareDatamodelEntryfields[archivalsource]{
    title,
    contains}
\DeclareDatamodelEntryfields[archivalitem]{
    author,
    title}
\end{filecontents}

\usepackage[datamodel=archival, backend=biber]{biblatex}

\addbibresource{\jobname.bib}

\DeclareBibliographyDriver{archivalitem}{%
  \usebibmacro{bibindex}%
  \usebibmacro{begentry}%
  \printnames{author} - %
  \printfield{title}%
  \usebibmacro{finentry}}

\newcommand{\entry}[1]{
    \item \entrydata{#1}{\usedriver{}{\thefield{entrytype}}}\adddot 
}

\DeclareFieldFormat{contains}{
  \printtext{Contains:}%
  \begin{enumerate}%
    \forcsvfield{\entry}{contains}
  \end{enumerate}%
}

\DeclareBibliographyDriver{archivalsource}{%
  \usebibmacro{bibindex}%
  \usebibmacro{begentry}%
  \printfield{title}. %
  \printfield{contains}%
  \iflistundef{contains}{\finentry}{}}

\begin{document}

Blah blah.\cite{Test}

\nocite{ITEM1, ITEM2} % otherwise they won't show up
\printbibliography[type=archivalsource]

\end{document}