Drive full introspsection and reporting back to gate via SQL cell \introspect (#72)

Author: James Robinson

noteable_magics/sql/gate_messaging_types.py

@@ -0,0 +1,179 @@
+# Declare the message types
+
+import enum
+from typing import List, Optional
+
+from pydantic import BaseModel, Field, root_validator
+
+r"""
+Messaging types used for SQL cell meta command \introspect when describing
+the structure of a discovered table or view up to Gate for permanent storage for
+front-end GUI schema navigation uses.
+
+These types culminating in RelationStructureDescription are inputs to the Gate
+POST route(s).
+"""
+
+
+@enum.unique
+class RelationKind(str, enum.Enum):
+    """Enumeration differentating between tables and views"""
+
+    table = "table"
+    view = "view"
+
+    class Config:
+        extra = "forbid"
+
+
+class ColumnModel(BaseModel):
+    """Pydantic model defining a column of an introspected table or view.
+
+    Used in two contexts:
+       * SQLAlchemy validation prior to assigning new value into DatasourceRelationDAO.columns JSONB column
+       * Subcomponent of upcoming pydantic model(s) used for route I/O (ENG-5356, ENG-5359).
+    """
+
+    name: str
+    is_nullable: bool
+    data_type: str
+    default_expression: Optional[str] = None
+    comment: Optional[str] = None
+
+    class Config:
+        extra = "forbid"
+
+
+class IndexModel(BaseModel):
+    """Pydantic model defining an introspected index.
+
+    Used in two contexts:
+       * SQLAlchemy validation prior to assigning new value into DatasourceRelationDAO.indexes JSONB column
+       * Subcomponent of upcoming pydantic models used for route I/O (ENG-5356, ENG-5359).
+    """
+
+    name: str
+    is_unique: bool
+    columns: List[str]
+
+    class Config:
+        extra = "forbid"
+
+
+class UniqueConstraintModel(BaseModel):
+    """Pydantic model defining an introspected unique constraint.
+
+    Used in two contexts:
+       * SQLAlchemy validation prior to assigning new value into DatasourceRelationDAO.unique_constraints JSONB column
+       * Subcomponent of upcoming pydantic models used for route I/O (ENG-5356, ENG-5359).
+    """
+
+    name: str
+    columns: List[str]
+
+    class Config:
+        extra = "forbid"
+
+
+class CheckConstraintModel(BaseModel):
+    """Pydantic model defining an introspected check constraint.
+
+    Used in two contexts:
+       * SQLAlchemy validation prior to assigning new value into DatasourceRelationDAO.check_constraints JSONB column
+       * Subcomponent of upcoming pydantic models used for route I/O (ENG-5356, ENG-5359).
+    """
+
+    name: str
+    expression: str
+
+    class Config:
+        extra = "forbid"
+
+
+class ForeignKeysModel(BaseModel):
+    """Pydantic model defining an introspected foreign key constraint.
+
+    Used in two contexts:
+       * SQLAlchemy validation prior to assigning new value into DatasourceRelationDAO.foreign_keys JSONB column
+       * Subcomponent of upcoming pydantic models used for route I/O (ENG-5356, ENG-5359).
+    """
+
+    name: str
+    referenced_schema: str
+    referenced_relation: str
+    columns: List[str]
+    referenced_columns: List[str]
+
+    @root_validator
+    def check_lists_same_length(cls, values):
+        if not ("columns" in values and "referenced_columns" in values):
+            raise ValueError("columns and referenced_columns required")
+
+        if len(values["columns"]) != len(values["referenced_columns"]):
+            raise ValueError("columns and referenced_columns must be same length")
+
+        return values
+
+    class Config:
+        extra = "forbid"
+
+
+class RelationStructureDescription(BaseModel):
+    """Pydantic model describing the POST structure kernel-space will use to describe a
+    schema-discovered table or view within a datasource.
+    """
+
+    # First, the singular fields.
+    schema_name: str = Field(
+        description="Name of schema containing the relation. Empty string for degenerate value."
+    )
+    relation_name: str = Field(description="Name of the table or view")
+    kind: RelationKind = Field(description="Relation type: table or a view")
+    relation_comment: Optional[str] = Field(description="Optional comment describing the relation.")
+    view_definition: Optional[str] = Field(description="Definition of the view if kind=view")
+    primary_key_name: Optional[str] = Field(
+        description="Name of the primary key constraint, if any"
+    )
+
+    # Now the plural fields.
+    primary_key_columns: List[str] = Field(
+        description="List of column names comprising the primary key, if any."
+    )
+    columns: List[ColumnModel] = Field(description="List of column definitions")
+    indexes: List[IndexModel] = Field(description="List of index definitions")
+    unique_constraints: List[UniqueConstraintModel] = Field(
+        description="List of unique constraint definitions"
+    )
+    check_constraints: List[CheckConstraintModel] = Field(
+        description="List of check constraint definitions"
+    )
+    foreign_keys: List[ForeignKeysModel] = Field(description="List of foreign key definitions")
+
+    @root_validator
+    def view_definition_vs_kind(cls, values):
+        """Fail if a tring to describe a view with None for the view definition. At worst
+        empty string is allowed.
+
+        Likewise, if describing a table, then view definition _must_ be None.
+        """
+        if not (values.get("view_definition") is None) == (
+            values.get("kind") == RelationKind.table
+        ):
+            raise ValueError("Views require definitions, tables must not have view definition")
+
+        return values
+
+    @root_validator
+    def pkey_name_only_if_has_pkey_columns(cls, values):
+        if len(values.get("primary_key_columns")) > 0 and not values.get('primary_key_name'):
+            raise ValueError("primary_key_columns requires nonempty primary_key_name")
+        elif (
+            len(values.get("primary_key_columns")) == 0
+            and values.get('primary_key_name') is not None
+        ):
+            raise ValueError("No primary_key_columns requires primary_key_name = None")
+
+        return values
+
+    class Config:
+        extra = "forbid"