Bibliography brackets are empty

Question

Somehow my Biblatex isnt working with alphabetical style.

Numerical style is working normally. My header looks like this:

\usepackage[
backend=biber,
style=alphabetic,
citestyle=authoryear
]{biblatex}
%
\addbibresource{literatur/literatur.bib}

citing with:

\cite{bsi}

and my .bib file looking like this:

@online{bsi,
    ALTauthor = {Bundesamt für Sicherheit in der Informationstechnik},
    title = {Cloud Computing Grundlagen},
    urldate = {2019-11-14},
    url = {https://www.bsi.bund.de/DE/Themen/DigitaleGesellschaft/CloudComputing/Grundlagen/Grundlagen_node.html}
}

Any ideas what might be the problem?

Answer 1

The standard definition for alphabetic labels tries to take the labelname field (one of author, editor, translator) and the date/year and combine the two into a combination along the lines of "SR98". One can use the label field to override the labelname part of the label or shorthand to override the complete label.

In the example entry none of the mentioned fields are filled, so biblatex does not manage to generate any label from the entry. It is at least possible to give the author, so I'd suggest something like

\documentclass[ngerman]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}

\usepackage[style=alphabetic, backend=biber]{biblatex}


\begin{filecontents}{\jobname.bib}
@online{bsi,
  author      = {{Bundesamt für Sicherheit in der Informationstechnik}},
  shortauthor = {BSI},
  title       = {Cloud Computing Grundlagen},
  url         = {https://www.bsi.bund.de/DE/Themen/DigitaleGesellschaft/CloudComputing/Grundlagen/Grundlagen_node.html},
  urldate     = {2019-11-14},
}
\end{filecontents}
\addbibresource{\jobname.bib}
\addbibresource{biblatex-examples.bib}


\begin{document}
\cite{sigfridsson,bsi}
\printbibliography
\end{document}

---

The entry key (bsi) should be thought of as a purely internal label. None of the common standard styles will ever use the entry key in the output.