schema.Table: Add add_child_row_location() and friends

Add the following methods:

 add_child_row_location(self, parent_table: Union[Self, str], **kwargs) -> Optional[str]
 add_child_row_location_rules(self) -> Iterable[str]
 add_child_row_location_rule(self, child_table: Union[Self, str]) -> Optional[str]

These are meant to be called from different pieces of code:

 - add_child_row_location() is meant to be used where the parent is
   rendered, to display a link to adding another child

 - add_child_row_location_rules() and add_child_row_location_rule()
   are meant to be invoked where processing is going to be done, i.e.
   likely code rendering child row content

Signed-off-by: Jan Lindemann <jan@janware.com>

tools/python/jwutils/db/schema/Table.py

@@ -39,10 +39,11 @@ class Table(abc.ABC): # export
         self.__location_rule: Optional[Iterable[str]]  = None
         self.__row_location_rule: Optional[Iterable[str]]  = None
         self.__add_row_location_rule: Optional[Iterable[str]]  = None
+        self.___add_child_row_location_rules: Optional[dict[str, str]]  = None
         self.__foreign_keys_to_parent_table: Optional[OrderedDict[str, Any]] = None
         self.__relationships: Optional[list[tuple[str, Self]]] = None
         self.__model_class: Optional[Any] = None
-        self.__relationship_by_foreign_table: Optional[dict[str, Self]] = None
+        self.___relationship_by_foreign_table: Optional[dict[str, Self]] = None
 
     @property
     def __columns(self) -> OrderedDict[str, Any]:
@@ -61,6 +62,26 @@ class Table(abc.ABC): # export
                 self.___foreign_key_parent_tables[cfk.parent_table.name] = cfk.parent_table
         return self.___foreign_key_parent_tables
 
+    @property
+    def __relationship_by_foreign_table(self) -> dict[str, Self]:
+        if self.___relationship_by_foreign_table is None:
+            ret: dict[str, Self] = dict()
+            for member_name, table_name in self.relationships:
+                ret[member_name] = self.schema[table_name]
+            self.___relationship_by_foreign_table = ret
+        return self.___relationship_by_foreign_table
+
+    @property
+    def __add_child_row_location_rules(self) -> dict[str, str]:
+        if self.___add_child_row_location_rules is None:
+            ret: dict[str, str] = {}
+            for foreign_table_name, foreign_table in self.__relationship_by_foreign_table.items():
+                if len(self.foreign_keys_to_parent_table(foreign_table)):
+                    rule = self._add_child_row_location_rule(foreign_table_name)
+                    ret[foreign_table_name] = rule
+            self.___add_child_row_location_rules = ret
+        return self.___add_child_row_location_rules
+
     def __len__(self):
         return len(self.__columns)
 
@@ -172,6 +193,17 @@ class Table(abc.ABC): # export
     def _add_row_location_rule(self) -> Optional[str]:
         return self._location_rule() + '/new'
 
+    def _add_child_row_location_rule(self, parent_table_name: str) -> Optional[str]:
+        parent_table = self.schema[parent_table_name]
+        ret = self._add_row_location_rule()
+        for cfk in self.foreign_keys_to_parent_table(parent_table):
+            for fk in cfk:
+                token = f'/<{fk.child_column.name}>'
+                if ret.find(token) != -1:
+                    continue
+                ret += f'/<{fk.child_column.name}>'
+        return ret
+
     # -- To be used
 
     def column_default(self, name) -> Any:
@@ -268,6 +300,27 @@ class Table(abc.ABC): # export
                 ret = re.sub(f'<{col}>', quote_plus(quote_plus(str(kwargs[col]))), ret)
         return ret
 
+    @property
+    def add_child_row_location_rules(self) -> Iterable[str]:
+        return self.__add_child_row_location_rules.values()
+
+    def add_child_row_location_rule(self, child_table: Union[Self, str]) -> Optional[str]:
+        if isinstance(child_table, Table):
+            child_table = child_table.name
+        return self.__add_child_row_location_rules.get(child_table)
+
+    def add_child_row_location(self, parent_table: Union[Self, str], **kwargs) -> Optional[str]:
+        ret = self.add_child_row_location_rule(parent_table)
+        if isinstance(parent_table, str):
+            parent_table = self.schema[parent_table]
+        if ret is None:
+            return None
+        for cfk in self.foreign_keys_to_parent_table(parent_table):
+            for fk in cfk:
+                if fk.parent_column.name in kwargs:
+                    ret = re.sub(f'<{fk.child_column.name}>', quote_plus(quote_plus(str(kwargs[fk.parent_column.name]))), ret)
+        return ret
+
     @property
     def primary_keys(self) -> Iterable[str]:
         if self.__primary_keys is None:
@@ -368,7 +421,7 @@ class Table(abc.ABC): # export
                     self.__foreign_keys_to_parent_table[pt] = []
                 self.__foreign_keys_to_parent_table[pt].append(cfk)
         parent_table_name = parent_table if isinstance(parent_table, str) else parent_table.name
-        return self.__foreign_keys_to_parent_table[parent_table_name]
+        return self.__foreign_keys_to_parent_table[parent_table_name] if parent_table_name in self.__foreign_keys_to_parent_table else []
 
     @property
     def relationships(self) -> list[tuple[str, Self]]:
@@ -382,9 +435,4 @@ class Table(abc.ABC): # export
     def relationship(self, table: Union[Self, str]) -> bool:
         if isinstance(table, Table):
             table = table.name
-        if self.__relationship_by_foreign_table is None:
-            ret: dict[str, Self] = dict()
-            for member_name, table_name in self.relationships:
-                ret[member_name] = self.schema[table_name]
-            self.__relationship_by_foreign_table = ret
         return self.__relationship_by_foreign_table.get(table)