diff --git a/database/database.py b/database/database.py
index 652cc14..6671d16 100644
--- a/database/database.py
+++ b/database/database.py
@@ -1,9 +1,13 @@
+from typing import List
+
 from sqlalchemy import Column, Boolean, Float, String, Integer, ForeignKey, Table, func, ForeignKeyConstraint
 import sqlalchemy
 from sqlalchemy.orm import declarative_base, relationship, load_only
 
+from database.models import Art, ArtnoID, Artist
+
 # TODO read sensitive data from environment file or similar
-SQLALCHEMY_DATABASE_URL = "postgresql://artnet_editor:G606Rm9sFEXe6wfTLxVu@127.0.0.1/artnet"
+SQLALCHEMY_DATABASE_URL = "postgresql://artnet_editor:G606Rm9sFEXe6wfTLxVu@127.0.0.1/test_artnet"
 engine = sqlalchemy.create_engine(SQLALCHEMY_DATABASE_URL, echo=True)
 SessionLocal = sqlalchemy.orm.sessionmaker(autocommit=False, autoflush=False, bind=engine)
 
@@ -12,8 +16,8 @@ Base = sqlalchemy.orm.declarative_base()
 
 
 art_tag_table = Table('art_tag', Base.metadata,
-                          Column('art_id', Integer, ForeignKey('art.id')),
-                          Column('tag_id', Integer, ForeignKey('tag.tag_id')))
+                      Column('art_id', Integer, ForeignKey('art.id')),
+                      Column('tag_id', Integer, ForeignKey('tag.tag_id')))
 artist_topic_table = Table('artist_topic', Base.metadata,
                            Column('artist_id', Integer, ForeignKey('artist.id')),
                            Column('topic_id', Integer, ForeignKey('topic.id')))
@@ -25,11 +29,11 @@ class DBPresence(Base):
     name = Column(String(20), primary_key=True)
     domain = Column(String(20), primary_key=True)
     link = Column(String, nullable=True)
-    artist_id = Column(Integer, ForeignKey('artist.id'), nullable=False, index=True)
+    artist_id = Column(Integer, ForeignKey('artist.id', ondelete="CASCADE"), nullable=False)
 
-    artist = relationship("DBArtist", backref='presences', foreign_keys=[artist_id])
-    #artists = relationship('DBArtist', foreign_keys='DBArtist.id', back_populates="presences")
-    arts = relationship("DBArt", secondary="art_author", viewonly=True)
+    artist = relationship("DBArtist", back_populates="presences")
+    arts = relationship("DBArt", secondary="art_author", back_populates="presences",
+                        cascade="delete, all")
 
 
 class DBArt(Base):
@@ -41,8 +45,9 @@ class DBArt(Base):
     title = Column(String, nullable=True)
     link = Column(String, nullable=True)
 
-    tags = relationship("DBTag", secondary=art_tag_table, back_populates="art")
-    presences = relationship("DBPresence", secondary="art_author", viewonly=True)
+    tags = relationship("DBTag", secondary=art_tag_table, back_populates="art", viewonly=True)
+    presences = relationship("DBPresence", secondary="art_author", back_populates="arts",
+                             cascade="all, delete")
 
 
 class DBArtPresence(Base):
@@ -50,11 +55,11 @@ class DBArtPresence(Base):
 
     presence_name = Column(String(20), primary_key=True)
     presence_domain = Column(String(20), primary_key=True)
-    art_id = Column(Integer, ForeignKey(DBArt.id), primary_key=True)
+    art_id = Column(Integer, ForeignKey(DBArt.id, ondelete="CASCADE"), primary_key=True)
 
     __table_args__ = (
         ForeignKeyConstraint(
-            ["presence_name", "presence_domain"],
+            ("presence_name", "presence_domain"),
             ["presence.name", "presence.domain"]
         ),
     )
@@ -64,9 +69,10 @@ class DBArtist(Base):
     __tablename__ = "artist"
 
     id = Column(Integer, primary_key=True)
-    description = Column(String, nullable=True)
+    description = Column(String, nullable=False)
 
-    topics = relationship("DBTopic", secondary="artist_topic", back_populates="artists")
+    topics = relationship("DBTopic", secondary="artist_topic", back_populates="artists", viewonly=True)
+    presences = relationship("DBPresence", back_populates="artist", cascade="all, delete")
 
 
 class DBTopic(Base):  # as of now unused
@@ -76,7 +82,7 @@ class DBTopic(Base):  # as of now unused
     name = Column(String(20), unique=True, nullable=False)
     description = Column(String)
 
-    artists = relationship("DBArtist", secondary="artist_topic", back_populates="topics")
+    artists = relationship("DBArtist", secondary="artist_topic", back_populates="topics", viewonly=True)
 
 
 class DBTagCategory(Base):
@@ -95,7 +101,9 @@ class DBTag(Base):
     category_id = Column(Integer, ForeignKey('tag_category.category_id'))
 
     category = relationship("DBTagCategory", backref='tags', foreign_keys=[category_id])
+    # TODO check if cascade is required
     art = relationship("DBArt", secondary=art_tag_table, back_populates="tags")
+    # TODO check if cascade is required
 
 
 Base.metadata.create_all(bind=engine)
@@ -103,31 +111,79 @@ Base.metadata.create_all(bind=engine)
 
 class Database:
 
+    __db: sqlalchemy.orm.Session = None
+
     def __get_db(self) -> sqlalchemy.orm.Session:
-        db = SessionLocal()
+        Database.__db = SessionLocal() if Database.__db is None else Database.__db
         try:
-            return db
+            return Database.__db
         finally:
-            db.close()
+            ##Database.__db.close()
+            pass
+
+    def __del__(self):
+        Database.__db.close()
+        Database.__db = None
 
 # Art
 
+    def get_art_list(self):
+        return self.__get_db().query(DBArt).all()  # TODO FIX StackOverflow
+
     def get_art_by_id(self, art_id: int):
         return self.__get_db().query(DBArt).where(DBArt.id == art_id).first()
 
     def get_art_by_hash(self, md5_hash: str):
         return self.__get_db().query(DBArt).filter(func.lower(DBArt.md5_hash) == md5_hash.lower()).first()
 
-    def update_art_by_id(self, art_id: int, title: str, authors: list, path: str, tags: list, link: str,
-                         md5_hash: str):
+    def create_art_by_model(self, art: ArtnoID):
+        if not (isinstance(art.path, str) and len(art.path) > 0):
+            raise ValueError("New Art must contain a path!")
+
+        db_art = DBArt(title=art.title, md5_hash=art.hash, path=art.path, link=art.link)
+
+        if self.get_art_by_hash(art.hash) is not None:
+            raise ValueError("New Art must not contain already known hashes! Is this really new?")
+
+        db = self.__get_db()
+        db.add(db_art)
+        db.commit()
+
+        # TODO implement saving art <-> presence relationship as given by art.presences
+        if art.presences is not None:
+            for presence in art.presences:
+                db_art_presence = DBArtPresence(presence_name=presence.name, presence_domain=presence.domain,
+                                                art_id=db_art.id)
+                db.add(db_art_presence)
+            db.commit()
+
+        return db_art.id
+
+    @DeprecationWarning
+    def update_art_by_id(self, art_id: int, title: str, path: str, tags: list, link: str,
+                         md5_hash: str, authors: list = None):
         raise NotImplementedError
 
-    def update_art_by_hash(self, md5_hash: str, title: str, authors: list, path: str, tags: list, link: str):
+    @DeprecationWarning
+    def update_art_by_hash(self, md5_hash: str, title: str, path: str, tags: list, link: str, authors: list = None):
         raise NotImplementedError
 
+    def update_art_by_model(self, art: Art):
+        db_art: DBArt = self.get_art_by_id(art.id)
+
+        db_art.title = art.title if art.title is not None else db_art.title
+        db_art.link = art.link if art.link is not None else db_art.link
+        db_art.md5_hash = art.hash if art.hash is not None else db_art.md5_hash
+        db_art.path = art.path if art.path is not None else db_art.path
+
+        self.__get_db().commit()
+
     def delete_art_by_id(self, art_id: int):
-        raise NotImplementedError
+        db_art: DBArt = self.get_art_by_id(art_id)
+        self.__get_db().delete(db_art)
+        self.__get_db().commit()
 
+    @DeprecationWarning
     def delete_art_by_hash(self, md5_hash: str):
         raise NotImplementedError
 
@@ -156,17 +212,40 @@ class Database:
 
     # Presence
 
+    def get_presence_list(self):
+        return self.__get_db().query(DBPresence).all()  # TODO fix StackOverflow
+
     def get_presence(self, name: str, domain: str) -> DBPresence:
         result = self.__get_db().query(DBPresence)\
             .filter(func.lower(DBPresence.name) == name.lower() and
                     func.lower(DBPresence.domain) == domain.lower()).first()
         return result
 
+    def create_presence(self, name: str, domain: str, artist_id: int, link: str):
+        if not (len(name) > 0 and len(domain) > 0):
+            print(f"Name: \"{name}\" Domain: \"{domain}\"")
+            raise ValueError("New Presence must have some name and domain!")
+
+        db_presence = DBPresence(name=name, domain=domain, artist_id=artist_id, link=link)
+
+        db = self.__get_db()
+        db.add(db_presence)
+        db.commit()
+
+        return db_presence.name, db_presence.domain
+
     def update_presence(self, name: str, domain: str, artist_id: int, link: str):
-        raise NotImplementedError
+        db_presence = self.get_presence(name=name, domain=domain)
+
+        db_presence.link = link
+        db_presence.artist_id = artist_id
+
+        self.__get_db().commit()
 
     def delete_presence(self, name: str, domain: str):
-        raise NotImplementedError
+        db_presence = self.get_presence(name=name, domain=domain)
+        self.__get_db().delete(db_presence)
+        self.__get_db().commit()
 
     # Artist -> Presence
 
@@ -176,15 +255,43 @@ class Database:
 
     # Artist
 
-    def get_artist(self, artist_id: int):
+    def get_artist_list(self):
+        return self.__get_db().query(DBArtist).all()  # TODO fix StackOverflow
+
+    def get_artist(self, artist_id: int) -> DBArtist:
         result = self.__get_db().query(DBArtist).where(DBArtist.id == artist_id).first()
         return result
 
-    def update_artist(self, artist_id: int, name: str):
-        raise NotImplementedError
+    def create_artist(self, name: str, topics: List[int]):
+        db_artist = DBArtist(description=name, topics=topics)
+
+        db = self.__get_db()
+        db.add(db_artist)
+        db.commit()
+
+        return db_artist
+
+    def search_artist(self, name: str) -> Artist:
+        result = self.__get_db().query(DBArtist).where(DBArtist.description == name).all()
+        return result
+
+    def update_artist(self, artist_id: int, name: str = None, topics: List[int] = None):
+        db_artist = self.get_artist(artist_id)
+
+        if name is not None:
+            db_artist.description = name
+        if topics is not None:
+            db_artist.topics = topics
+
+        self.__get_db().commit()
 
     def delete_artist(self, artist_id: int):
-        raise NotImplementedError
+        db_artist = self.get_artist(artist_id)
+
+        self.__get_db().delete(db_artist)
+        self.__get_db().commit()  # TODO FIX sqlalchemy.exc.IntegrityError: (psycopg2.errors.ForeignKeyViolation)
+                                    # TODO update or delete on table "artist" violates foreign key constraint "presence_artist_id_fkey" on table "presence"
+                                    # TODO DETAIL:  Key (id)=(83) is still referenced from table "presence".
 
     # Topic
 
diff --git a/database/models.py b/database/models.py
index ff07135..af45df3 100644
--- a/database/models.py
+++ b/database/models.py
@@ -2,12 +2,57 @@ from pydantic import BaseModel
 from typing import List, Optional
 
 
-class Art(BaseModel):
-    id: int
-    hash: str
-    path: str
-    title: Optional[str] = None
-    link: Optional[str] = None
+class TopicNoId(BaseModel):
+    name: str
+    description: Optional[str]
 
     class Config:
         orm_mode = True
+
+
+class Topic(TopicNoId):
+    topic_id: int
+
+
+class ArtistNoId(BaseModel):
+    description: str
+    topics: Optional[List[int]]
+
+    class Config:
+        orm_mode = True
+
+
+class Artist(ArtistNoId):
+    artist_id: int
+
+    class Config:
+        orm_mode = True
+
+
+class Presence(BaseModel):
+    name: str
+    domain: str
+    link: Optional[str]
+    artist_id: Optional[int]
+
+    class Config:
+        orm_mode = True
+
+
+class ArtnoID(BaseModel):
+    hash: Optional[str]
+    path: Optional[str]
+    title: Optional[str] = None
+    link: Optional[str] = None
+    presences: Optional[List[Presence]]
+
+    class Config:
+        orm_mode = True
+
+
+class Art(ArtnoID):
+    id: int
+
+    class Config:
+        orm_mode = True
+
diff --git a/main.py b/main.py
index 5dc3ce2..0e67d84 100644
--- a/main.py
+++ b/main.py
@@ -1,7 +1,9 @@
 from fastapi import FastAPI, HTTPException
 import uvicorn
+from typing import List, Tuple
 
 from database.database import Database
+from database.models import Art, ArtnoID, Presence, ArtistNoId
 
 app = FastAPI()
 db = Database()
@@ -9,8 +11,9 @@ db = Database()
 
 @app.get("/artnet/metadata/art")
 async def art(id: int = None, hash: str = None, tag_id: int = None):
-    if id is None and hash is None and tag_id is None:
-        raise HTTPException(status_code=406, detail="requires id or hash param")
+    print(f"Received GET on /artnet/metadata/art (id={id}, hash={hash}, tag_id={tag_id})")
+    #if id is None and hash is None and tag_id is None:
+        #raise HTTPException(status_code=406, detail="requires id or hash param")
 
     result = None
     if id is not None:
@@ -20,17 +23,63 @@ async def art(id: int = None, hash: str = None, tag_id: int = None):
     elif tag_id is not None:
         result = db.get_tag_art(tag_id)
 
+    if id is None and hash is None and tag_id is None:  # TODO fix against listing enormous amounts of art (because all could be large)
+        result = db.get_art_list()
+
     if result is not None:
         return result
     raise HTTPException(status_code=404, detail="Art was not found!")
 
 
+@app.post("/artnet/metadata/art")
+async def art(art: ArtnoID, id: int = None):
+    print(f"Received POST on /artnet/metadata/art (id={id}) body: art=({art})")
+    if id is None:  # create new art entry
+        if art.presences is None:  # tried to create art without any presence
+            raise HTTPException(status_code=422, detail="No presences were listed")
+        try:
+            for presence in art.presences:
+                r = db.get_presence(name=presence.name, domain=presence.domain)
+                #if db.get_presence(name=presence.name, domain=presence.domain) is None:
+                #    raise HTTPException(status_code=422,
+                #                        detail=f"Presence ({presence.name}, {presence.domain}) is unknown!")
+                #db.create  # create presence-art relationship
+                # TODO validate & create presence-art relationship
+
+            new_id = db.create_art_by_model(art)
+            return {"id": new_id}
+        except ValueError as e:
+            raise HTTPException(status_code=422, detail=str(e))
+    else:  # update existing art entry
+        if db.get_art_by_id(id) is None:
+            return HTTPException(status_code=404, detail="The specified art could not be found!")
+
+        # TODO implement linking to one or multiple presences
+        # TODO enforcing at least one presence
+        updated_art = Art(id=id)
+        updated_art.hash = art.hash
+        updated_art.link = art.link
+        updated_art.title = art.title
+        updated_art.path = art.path
+
+        db.update_art_by_model(updated_art)
+
+        return True
+
+
+@app.delete("/artnet/metadata/art")
+async def art(id: int):
+    print(f"Received DELETE on /artnet/metadata/art (id={id})")
+    if db.get_art_by_id(id) is None:
+        raise HTTPException(status_code=404, detail="Art has not been found!")
+    db.delete_art_by_id(id)
+
+
 @app.get("/artnet/metadata/presence")
 async def presence(name: str = None, domain: str = None, artist_id: int = None, art_id: int = None,
                    art_md5: str = None):
-    if name is None and domain is None and artist_id is None and art_id is None and art_md5 is None:
-        raise HTTPException(status_code=406, detail="You must query with at least one parameter!")
-
+    print(f"Received GET on /artnet/metadata/presence (name={name}, domain={domain}, artist_id={artist_id}"
+          f", art_id={art_id}, art_md5={art_md5})")
     result = None
     if artist_id is not None and name is None and domain is None:
         result = db.get_artist_presences(artist_id)
@@ -44,28 +93,84 @@ async def presence(name: str = None, domain: str = None, artist_id: int = None,
     elif name is not None and domain is not None:
         result = db.get_presence(name, domain)
 
+    if name is None and domain is None and artist_id is None and art_id is None and art_md5 is None:
+        result = db.get_presence_list()
+        #raise HTTPException(status_code=406, detail="You must query with at least one parameter!")
+
     if result is not None:
         return result
     raise HTTPException(status_code=404, detail="Presence was not found!")
 
 
-@app.get("/artnet/metadata/artist")
-async def artist(id: int = None, topic_id: int = None):
-    if id is None and topic_id is None:
-        raise HTTPException(status_code=406)
+@app.post("/artnet/metadata/presence")
+async def presence(presence: Presence):
+    print(f"Received POST on /artnet/metadata/presence body: presence={presence}")
+    curr_presence = db.get_presence(name=presence.name, domain=presence.domain)
 
+    r = db.get_artist(presence.artist_id)
+    if r is None:
+        raise HTTPException(status_code=406, detail="Invalid Artist ID! Could not find artist.")
+
+    if curr_presence is None:  # must be new presence
+        db.create_presence(name=presence.name, domain=presence.domain, artist_id=presence.artist_id, link=presence.link)
+    else:  # editing current presence
+        db.update_presence(name=curr_presence.name, domain=curr_presence.domain,
+                           artist_id=presence.artist_id, link=presence.link)
+
+
+@app.delete("/artnet/metadata/presence")
+async def presence(name: str, domain: str):
+    print(f"Received DELETE on /artnet/metadata/presence (name={name}, domain={domain})")
+    if db.get_presence(name, domain) is None:
+        raise HTTPException(status_code=404, detail="Presence has not been found!")
+    db.delete_presence(name, domain)
+
+
+@app.get("/artnet/metadata/artist")
+async def artist(id: int = None, topic_id: int = None, description: str = None):
+    print(f"Received GET on /artnet/metadata/artist (id={id}, topic_id={topic_id}, description={description})")
     result = None
+    if id is None and topic_id is None and description is None:
+        result = db.get_artist_list()
+
     if id is not None:
         result = db.get_artist(id)
     elif topic_id is not None:
         result = db.get_topic_artists(topic_id)
+    elif description is not None:
+        result = db.search_artist(description)
+
     if result is not None:
         return result
     raise HTTPException(status_code=404, detail="Artist was not found!")
 
 
+@app.post("/artnet/metadata/artist")
+async def artist(artist: ArtistNoId, id: int = None):
+    print(f"Received POST on /artnet/metadata/artist (id={id}) body: artist={artist}")
+    if id is None:  # create new artist
+        db_artist = db.create_artist(name=artist.description, topics=artist.topics)
+        return db_artist.id
+
+    else:
+        if db.get_artist(id) is not None:
+            db.update_artist(artist_id=id, name=artist.description, topics=artist.topics)
+        else:
+            raise HTTPException(status_code=404, detail="Tried to edit unknown artist. ID was not found!")
+
+
+@app.delete("/artnet/metadata/artist")
+async def artist(id: int):
+    print(f"Received DELETE on /artnet/metadata/artist (id={id})")
+    if db.get_artist(id) is None:
+        raise HTTPException(status_code=404, detail="Tried to delete unknown artist. ID was not found!")
+    db.delete_artist(id)
+
+
+
 @app.get("/artnet/metadata/topic")
 async def topic(name: str = None, id: int = None, artist_id: int = None):
+    print(f"Received GET on /artnet/metadata/topic (name={name}, id={id}, artist_id={artist_id})")
     if name is None and id is None and artist_id is None:
         raise HTTPException(status_code=406)