deploy: add support for managing SQL views

src/rex.deploy/src/rex/deploy/image.py

@@ -6,6 +6,7 @@
 from .sql import (sql_create_schema, sql_drop_schema, sql_rename_schema,
         sql_create_extension, sql_drop_extension, sql_comment_on_schema,
         sql_create_table, sql_drop_table, sql_rename_table,
+        sql_create_view, sql_drop_view, sql_rename_view, sql_comment_on_view,
         sql_comment_on_table, sql_define_column, sql_add_column,
         sql_drop_column, sql_rename_column, sql_copy_column,
         sql_set_column_type, sql_set_column_not_null, sql_set_column_default,
@@ -329,6 +330,10 @@ def add_table(self, name, is_unlogged=False):
         """Adds a table."""
         return TableImage(self, name, is_unlogged=is_unlogged)
 
+    def add_view(self, name, definition):
+        """Adds a view."""
+        return ViewImage(self, name, definition)
+
     def add_index(self, name, table, columns):
         """Adds an index."""
         return IndexImage(self, name, table, columns)
@@ -370,6 +375,14 @@ def create_table(self, name, definitions, is_unlogged=False):
             table.add_column(column_name, type, is_not_null, default)
         return table
 
+    def create_view(self, name, definition):
+        """Creates a view with the given definition."""
+        qname = (self.name, name)
+        sql = sql_create_view(qname, definition)
+        self.cursor.execute(sql)
+        view = self.add_view(name, definition=definition)
+        return view
+
     def create_index(self, name, table, columns):
         """Creates an index."""
         column_names = [column.name for column in columns]
@@ -880,6 +893,48 @@ def drop(self):
         self.remove()
 
 
+class ViewImage(NamespacedImage):
+    """Database view."""
+
+    __slots__ = ('comment', 'definition')
+
+    def __init__(self, schema, name, definition):
+        super(NamespacedImage, self).__init__(schema, name)
+        self.place(schema.tables)
+        schema.link(self)
+        #: View comment.
+        self.comment = None
+        #: View definition.
+        self.definition = definition
+
+    def set_comment(self, comment):
+        """Sets the comment."""
+        self.comment = comment
+        return self
+
+    def alter_name(self, name):
+        """Renames the view."""
+        if self.name == name:
+            return self
+        sql = sql_rename_view(self.qname, name)
+        self.cursor.execute(sql)
+        return self.set_name(name)
+
+    def alter_comment(self, comment):
+        """Updates the view comment."""
+        if self.comment == comment:
+            return self
+        sql = sql_comment_on_view(self.qname, comment)
+        self.cursor.execute(sql)
+        return self.set_comment(comment)
+
+    def drop(self):
+        """Drops the view."""
+        sql = sql_drop_view(self.qname)
+        self.cursor.execute(sql)
+        self.remove()
+
+
 class ColumnImage(NamedImage):
     """Database column."""
 

src/rex.deploy/src/rex/deploy/introspect.py

@@ -93,7 +93,7 @@ def introspect(cursor):
     cursor.execute("""
         SELECT c.oid, c.relnamespace, c.relname, c.relpersistence
         FROM pg_catalog.pg_class c
-        WHERE c.relkind IN ('r', 'v') AND
+        WHERE c.relkind IN ('r') AND
               HAS_TABLE_PRIVILEGE(c.oid, 'SELECT')
         ORDER BY c.relnamespace, c.relname
     """)
@@ -103,12 +103,27 @@ def introspect(cursor):
         table = schema.add_table(relname, is_unlogged=is_unlogged)
         class_by_oid[oid] = table_by_oid[oid] = table
 
+    # Extract views.
+    cursor.execute("""
+        SELECT c.oid, c.relnamespace, c.relname, pg_get_viewdef(c.oid)
+        FROM pg_catalog.pg_class c
+        WHERE c.relkind IN ('v') AND
+              HAS_TABLE_PRIVILEGE(c.oid, 'SELECT')
+        ORDER BY c.relnamespace, c.relname
+    """)
+    for oid, relnamespace, relname, definition in cursor.fetchall():
+        schema = schema_by_oid[relnamespace]
+        table = schema.add_view(relname, definition)
+        class_by_oid[oid] = table_by_oid[oid] = table
+
     # Extract columns.
     column_by_num = {}
     cursor.execute("""
         SELECT a.attrelid, a.attnum, a.attname, a.atttypid, a.atttypmod,
                a.attnotnull, a.atthasdef, a.attisdropped
         FROM pg_catalog.pg_attribute a
+        JOIN pg_catalog.pg_class c ON a.attrelid = c.oid
+        WHERE c.relkind IN ('r')
         ORDER BY a.attrelid, a.attnum
     """)
     for (attrelid, attnum, attname, atttypid,

src/rex.deploy/src/rex/deploy/meta.py

@@ -7,7 +7,7 @@
         Location, set_location, UStrVal, UChoiceVal, MaybeVal, SeqVal,
         RecordVal, Error)
 from .fact import LabelVal, TitleVal, AliasVal, AliasSpec, FactDumper
-from .image import TableImage, ColumnImage, UniqueKeyImage
+from .image import TableImage, ViewImage, ColumnImage, UniqueKeyImage
 import operator
 import collections
 import yaml
@@ -133,6 +133,17 @@ class TableMeta(Meta):
     ]
 
 
+class ViewMeta(Meta):
+    """View metadata."""
+
+    __slots__ = ()
+
+    fields = [
+            ('label', LabelVal, None),
+            ('title', TitleVal, None),
+    ]
+
+
 class ColumnMeta(Meta):
     """Column metadata."""
 
@@ -162,6 +173,8 @@ def uncomment(image):
     """
     if isinstance(image, TableImage):
         return TableMeta.parse(image.comment)
+    if isinstance(image, ViewImage):
+        return ViewMeta.parse(image.comment)
     elif isinstance(image, ColumnImage):
         return ColumnMeta.parse(image.comment)
     elif isinstance(image, UniqueKeyImage) and image.is_primary:

src/rex.deploy/src/rex/deploy/model.py

@@ -12,7 +12,7 @@
         plpgsql_primary_key_procedure, plpgsql_integer_random_key,
         plpgsql_text_random_key, plpgsql_integer_offset_key,
         plpgsql_text_offset_key, plpgsql_text_uuid_key)
-from .image import (TableImage, ColumnImage, UniqueKeyImage, CASCADE,
+from .image import (TableImage, ColumnImage, ViewImage, UniqueKeyImage, CASCADE,
         SET_DEFAULT, BEFORE, AFTER, INSERT, INSERT_UPDATE_DELETE)
 from .cluster import Cluster, get_cluster
 import datetime
@@ -257,12 +257,24 @@ def table(self, label):
         """
         return TableModel.find(self, label)
 
+    def view(self, label):
+        """
+        Finds the view by name.
+        """
+        return ViewModel.find(self, label)
+
     def build_table(self, **kwds):
         """
         Creates a new table.
         """
         return TableModel.do_build(self, **kwds)
 
+    def build_view(self, **kwds):
+        """
+        Creates a new view.
+        """
+        return ViewModel.do_build(self, **kwds)
+
     def facts(self):
         """
         Returns a list of facts that reproduce the schema.
@@ -334,6 +346,8 @@ def find(cls, schema, label):
         # Finds a table by name.
         names = cls.names(label)
         image = schema.image.tables.get(names.name)
+        if not isinstance(image, TableImage):
+            image = None
         return schema(image)
 
     @classmethod
@@ -578,6 +592,93 @@ def fact(self, with_related=False):
                 related=related)
 
 
+class ViewModel(Model):
+    """
+    Wraps a database view.
+    """
+
+    __slots__ = ('label', 'title', 'definition')
+
+    is_table = False
+
+    properties = ['label', 'title', 'definition']
+
+    class names:
+        # Derives names for database objects and the view title.
+
+        __slots__ = ('label', 'title', 'name')
+
+        def __init__(self, label):
+            self.label = label
+            self.title = label_to_title(label)
+            self.name = mangle(label)
+
+    @classmethod
+    def recognizes(cls, schema, image):
+        # Verifies if the database object is a table.
+        if not isinstance(image, ViewImage):
+            return False
+        # We expect the table belongs to the `public` schema.
+        if image.schema is not schema.image:
+            return False
+        return True
+
+    @classmethod
+    def find(cls, schema, label):
+        # Finds a table by name.
+        names = cls.names(label)
+        image = schema.image.tables.get(names.name)
+        if not isinstance(image, ViewImage):
+            image = None
+        return schema(image)
+
+    @classmethod
+    def do_build(cls, schema, label, definition, title=None):
+        # Builds a view.
+        names = cls.names(label)
+        image = schema.image.create_view(names.name, definition)
+        # Save the label and the title if necessary.
+        saved_label = label if label != names.name else None
+        saved_title = title if title != names.title else None
+        meta = uncomment(image)
+        if meta.update(label=saved_label, title=saved_title):
+            image.alter_comment(meta.dump())
+        return cls(schema, image)
+
+    def __init__(self, schema, image):
+        super(ViewModel, self).__init__(schema, image)
+        assert isinstance(image, ViewImage)
+        # Extract entity properties.
+        meta = uncomment(image)
+        self.label = meta.label or image.name
+        self.title = meta.title
+        self.definition = image.definition
+
+    def do_modify(self, label, title, definition):
+        # Updates the state of the view entity.
+        # Refresh names.
+        names = self.names(label)
+        self.image.alter_name(names.name)
+        # Update saved label and title.
+        meta = uncomment(self.image)
+        saved_label = label if label != names.name else None
+        saved_title = title if title != names.title else None
+        if meta.update(label=saved_label, title=saved_title):
+            self.image.alter_comment(meta.dump())
+
+    def do_erase(self):
+        # Drops the entity.
+        if self.image:
+            self.image.drop()
+
+    def fact(self):
+        from .table import ViewFact
+        return ViewFact(
+                self.label,
+                definition=self.image.definition,
+                title=self.title)
+
+
 class ColumnModel(Model):
     """
     Wraps a table column.

src/rex.deploy/src/rex/deploy/sql.py

@@ -288,6 +288,33 @@ def sql_comment_on_table(qname, text):
     COMMENT ON TABLE {{ qname|qn }} IS {{ text|v }};
     """
 
+@sql_template
+def sql_create_view(qname, definition):
+    """
+    CREATE VIEW {{ qname|qn }} AS ({{ definition }});
+    """
+
+
+@sql_template
+def sql_drop_view(qname):
+    """
+    DROP VIEW {{ qname|qn }};
+    """
+
+
+@sql_template
+def sql_rename_view(qname, new_name):
+    """
+    ALTER VIEW {{ qname|qn }} RENAME TO {{ new_name|n }};
+    """
+
+
+@sql_template
+def sql_comment_on_view(qname, text):
+    """
+    COMMENT ON VIEW {{ qname|qn }} IS {{ text|v }};
+    """
+
 
 @sql_template
 def sql_define_column(name, type_qname, is_not_null, default=None):