Question : I am a foreigner studying in Germany, am I allowed to have a part-time job? What are the requirements I need to have to work part time as a foreign student here?

If you are a citizen of the European Union (EU) or citizen of the European Economic Area (EEA), you have, like German students, free access to the German job market. If you come from one other country, you are allowed to work 240 half or 120 full days per year, except in the position of research assistant for which there is no time limit.
In order to be allowed to work more than 240 half or 120 full days per year, you will need the authorisation of the Federal Employment Agency (Agentur für Arbeit) and of the Federal Office for Migration and Refugees. Whether you are issued this authorisation largely depends on the local job market. You are more likely to receive it in regions with lower unemployment rates.