drop expression support

migra/changes.py

@@ -276,7 +276,17 @@ def get_table_changes(
 
             inheritance_status_changed = c.is_inherited != c_before.is_inherited
 
-            if inheritance_status_changed or generated_status_changed:
+            generated_status_removed = not c.is_generated and c_before.is_generated
+
+            can_drop_generated = (
+                generated_status_removed and c_before.can_drop_generated
+            )
+
+            drop_and_recreate_required = inheritance_status_changed or (
+                generated_status_changed and not can_drop_generated
+            )
+
+            if drop_and_recreate_required:
                 del c_modified[k]
 
                 if not c_before.is_inherited:
@@ -285,6 +295,9 @@ def get_table_changes(
                 if not c.is_inherited:
                     c_added[k] = c
 
+            if generated_status_changed:
+                pass
+
         for k, c in c_removed.items():
             alter = v.alter_table_statement(c.drop_column_clause)
             statements.append(alter)

poetry.lock

@@ -334,7 +334,7 @@ jupyter = ["ipywidgets (>=7.5.1,<8.0.0)"]
 
 [[package]]
 name = "schemainspect"
-version = "3.1.1663062229"
+version = "3.1.1663480743"
 description = "Schema inspection for PostgreSQL (and possibly others)"
 category = "main"
 optional = false
@@ -742,8 +742,8 @@ rich = [
     {file = "rich-12.5.1.tar.gz", hash = "sha256:63a5c5ce3673d3d5fbbf23cd87e11ab84b6b451436f1b7f19ec54b6bc36ed7ca"},
 ]
 schemainspect = [
-    {file = "schemainspect-3.1.1663062229-py3-none-any.whl", hash = "sha256:ca6ab497e90a1e4c4dd7406b1d38efdbf478d7c482408e3a8852b2dfa686a5f6"},
-    {file = "schemainspect-3.1.1663062229.tar.gz", hash = "sha256:625507658f4971a4a3cd0a4afe7ce40e66158fe5fcbd57f426e307434f5742e6"},
+    {file = "schemainspect-3.1.1663480743-py3-none-any.whl", hash = "sha256:852813d0ee38985242373708b8441c5fbcff611d30dae013afb5cb7d7148c95a"},
+    {file = "schemainspect-3.1.1663480743.tar.gz", hash = "sha256:b042676ceffd189983f38a42042dfb19d86925f8c4f8bdd6d40334582fdb116b"},
 ]
 six = [
     {file = "six-1.16.0-py2.py3-none-any.whl", hash = "sha256:8abb2f1d86890a2dfb989f9a77cfcfd3e47c2a354b01111771326f8aa26e0254"},

pyproject.toml

@@ -14,7 +14,7 @@ python = ">=3.7,<4"
 sqlbag = "*"
 six = "*"
 # schemainspect = {path="../schemainspect", develop=true}
-schemainspect = ">=3.1.1658648837"
+schemainspect = ">=3.1.1663480743"
 psycopg2-binary = { version="*", optional = true }
 
 [tool.poetry.dev-dependencies]

tests/FIXTURES/generated/a.sql

@@ -0,0 +1,15 @@
+-- create table t(
+--     a int,
+--     adding int,
+--     modifying int generated always as identity,
+--     removing int generated by default as identity
+-- );
+
+create table t();
+
+CREATE TABLE "demo_gencol" (
+            "id" serial           PRIMARY KEY, -- PRIMARY KEY
+    "the_column" TEXT               NULL GENERATED ALWAYS AS ('the original generated value') STORED, -- The column that is originally GENERATED, then changed not to be
+    "the_column2" text
+);
+

tests/FIXTURES/generated/b.sql

@@ -0,0 +1,17 @@
+-- create table t(
+--     a int,
+--     adding int generated always as (1) stored,
+--     modifying int generated always as (1) stored,
+--     removing int
+-- );
+
+
+
+
+
+CREATE TABLE "demo_gencol" (
+            "id" serial           PRIMARY KEY, -- PRIMARY KEY
+    "the_column" text,
+    "the_column2" TEXT               NULL GENERATED ALWAYS AS ('the original generated value') STORED -- The column that is originally GENERATED, then changed not to be
+);
+

tests/FIXTURES/generated/expected.sql

@@ -0,0 +1,7 @@
+drop table "public"."t";
+
+alter table "public"."demo_gencol" drop column "the_column2";
+
+alter table "public"."demo_gencol" add column "the_column2" text generated always as ('the original generated value'::text) stored;
+
+alter table "public"."demo_gencol" alter column "the_column" drop expression;

tests/FIXTURES/generated_added/a.sql

@@ -0,0 +1,13 @@
+-- create table t(
+--     a int,
+--     adding int,
+--     modifying int generated always as identity,
+--     removing int generated by default as identity
+-- );
+
+create table t();
+
+CREATE TABLE "demo_gencol" (
+            "id" serial           PRIMARY KEY , -- PRIMARY KEY
+    "the_column" TEXT               NULL -- The column that is originally GENERATED, then changed not to be
+);

tests/FIXTURES/generated_added/b.sql

@@ -0,0 +1,13 @@
+-- create table t(
+--     a int,
+--     adding int generated always as (1) stored,
+--     modifying int generated always as (1) stored,
+--     removing int
+-- );
+
+
+
+CREATE TABLE "demo_gencol" (
+            "id" serial           PRIMARY KEY , -- PRIMARY KEY
+    "the_column" TEXT               NULL -- The column that is originally GENERATED, then changed not to be
+);

tests/FIXTURES/generated_added/expected.sql

@@ -0,0 +1 @@
+alter table "public"."demo_gencol" alter column "the_column" drop expression;

tests/FIXTURES/identitycols/expected.sql

@@ -11,11 +11,9 @@ create table "public"."t2" (
 
 alter table "public"."gen" drop column "adding";
 
-alter table "public"."gen" drop column "removing";
-
 alter table "public"."gen" add column "adding" integer generated always as (1) stored;
 
-alter table "public"."gen" add column "removing" integer;
+alter table "public"."gen" alter column "removing" drop expression;
 
 alter table "public"."identchanges" alter column "c" drop default;
 

tests/test_migra.py

@@ -83,6 +83,7 @@ dependencies2
 dependencies3
 dependencies4
 constraints
+generated
 """.split()