footcite equals texcite with special format (parenthesis around year and given name initials)

Question

I need to use a special footcite and textcite format for my master thesis. They should both look like

Cite with footnote and textcite.\footnote{Vgl. \textcite{A01}, S. 23.}
Cite with footcite.\footcite[Vgl.][S. 23]{A01}

I tried different solutions for the initials in footcite, but they would corrupt the output of textcite. Here is the version without the initials.

Minimal working example:

\documentclass{article}
\usepackage[utf8]{inputenc}

\usepackage[
backend=biber,
bibencoding=utf8,
style=ext-authoryear,
giveninits=true,
dashed=false,
doi=false,
date=year,
isbn=false,
uniquename=init]{biblatex}
\usepackage{filecontents}

\begin{filecontents}{\jobname.bib}
@article{A01,        
  author = {Author, A.},
  year = {2001},
  title = {Alpha},
  journaltitle = {A Journal},
  volume = {1},
  number = {1},
}
\end{filecontents}
\addbibresource{\jobname.bib}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% footnotestyle format
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Parathenthesis around year in footcite
\DeclareInnerCiteDelims{footcite}{\bibopenparen}{\bibcloseparen}

% indentation
\usepackage[hang,bottom,stable]{footmisc}
\setlength{\footnotemargin}{5mm}
\interfootnotelinepenalty=10000 

% given name initials for footcite and textcite
% ???

\begin{document}
Cite with footnote and textcite.\footnote{Vgl. \textcite{A01}, S. 23.}
Cite with footcite.\footcite[Vgl.][S. 23]{A01}
\printbibliography
\end{document}

Answer 1

You can modify the labelname name format. The original definition can be found in biblatex.def (ll. 955-981 in v3.16). (Cf. also How to include first initials when using authoryear referencing format (harvard) with biblatex?)

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

\usepackage[
  backend=biber,
  style=ext-authoryear,
  giveninits=true,
  uniquename=init,
  dashed=false,
  date=year,
  doi=false,
  isbn=false,
]{biblatex}

\addbibresource{biblatex-examples.bib}

\DeclareInnerCiteDelims{footcite}{\bibopenparen}{\bibcloseparen}
\DeclareInnerCiteDelims{cite}{\bibopenparen}{\bibcloseparen}

\DeclareNameFormat{labelname}{%
  \ifnum\value{uniquename}<2
    \usebibmacro{name:family-given}
      {\namepartfamily}
      {\namepartgiveni}
      {\namepartprefix}
      {\namepartsuffix}%
  \else
    \usebibmacro{name:family-given}
      {\namepartfamily}
      {\namepartgiven}
      {\namepartprefix}
      {\namepartsuffix}%
  \fi
  \usebibmacro{name:andothers}}

\begin{document}
Cite with foonote and textcite.\footnote{\Cite[Vgl.][23]{nussbaum},
  and much more text.}
Cite with footcite.\footcite[Vgl.][23]{nussbaum}
\printbibliography
\end{document}

---

I wouldn't use \textcite here because you don't want its placement of pre- and postnote. But you can easily repurpose \cite for that job.

In the example I would definitely prefer

 \footcite[Vgl.][23]{nussbaum}

over

 \footnote{\Cite[Vgl.][23]{nussbaum}.}

but if you include additional text (as in the MWE), it may make sense to use the latter form.