[0.2.0] Metadata Implementation

sdgx/data_models/metadata.py

@@ -34,9 +34,7 @@ class Metadata(BaseModel):
 
     # for primary key
     # compatible with single primary key or composite primary key
-    primary_key: str = "primary_key undefined"
-    _composite_primary_key: bool = False
-    primary_key_list: list = []
+    primary_keys: List[str] = []
 
     # variables related to columns
     # column_list is used to store all columns' name

sdgx/data_models/multi_table_combiner.py

@@ -1,2 +1,54 @@
-class MultiTableCombiner:
-    pass
+from typing import Any, Dict, List
+
+from pydantic import BaseModel
+
+from sdgx.data_models.metadata import Metadata
+from sdgx.data_models.relationship import Relationship
+
+
+class MultiTableCombiner(BaseModel):
+    """MultiTableCombiner: combine different tables using relationship
+
+    Args:
+        metadata_dict (Dict[str, Any]):
+
+        relationships (List[Any]):
+    """
+
+    metadata_version: str = "1.0"
+
+    metadata_dict: Dict[str, Any] = {}
+    relationships: List[Any] = []
+
+    def check(self):
+        """Do necessary checks:
+
+        - Whether number of tables corresponds to relationships.
+        - Whether table names corresponds to the relationship between tables;
+        """
+
+        # count check
+        relationship_cnt = len(self.relationships)
+        metadata_cnt = len(self.metadata_dict.keys())
+        if metadata_cnt != relationship_cnt + 1:
+            raise ValueError("Number of tables should corresponds to relationships.")
+
+        # table name check
+        table_names_from_relationships = set()
+
+        # each relationship's table must have metadata
+        table_names = list(self.metadata_dict.keys())
+        for each_r in self.relationships:
+            if each_r.parent_table not in table_names:
+                raise ValueError(f"Metadata of parent table {each_r.parent_table} is missing.")
+            if each_r.child_table not in table_names:
+                raise ValueError(f"Metadata of child table {each_r.child_table} is missing.")
+            table_names_from_relationships.add(each_r.parent_table)
+            table_names_from_relationships.add(each_r.child_table)
+
+        # each table in metadata must in a relationship
+        for each_t in table_names:
+            if each_t not in table_names_from_relationships:
+                raise ValueError(f"Table {each_t} has not relationship.")
+
+        return True

sdgx/data_models/relationship.py

@@ -1,3 +1,5 @@
+from typing import List
+
 from pydantic import BaseModel
 
 
@@ -16,8 +18,12 @@ class Relationship(BaseModel):
     parent_table: str
     child_table: str
 
-    # keys
-    child_table_foreign_key: str
+    # foreign keys
+    child_table_foreign_key: str = "foreign key undefined"
+
+    # for composite keys
+    composite_foreign_key: bool = False
+    child_table_composite_foreign_key: List[str] = []
 
     def __init__(self, **kwargs):
         super().__init__(**kwargs)