Support inspection of computed column

Added support for reflection of "computed" columns, which are now returned
as part of the structure returned by :meth:`.Inspector.get_columns`.
When reflecting full :class:`.Table` objects, computed columns will
be represented using the :class:`.Computed` construct.

Also improve the documentation in :meth:`Inspector.get_columns`, correctly
listing all the returned keys.

Fixes: #5063
Fixes: #4051

Closes: #5064
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5064
Pull-request-sha: ba00fc321ce468f8885aad23b3dd33c789e50fbe

Change-Id: I789986554fc8ac7f084270474d0b2c12046b1cc2

1 files changed, 10 insertions, 0 deletions

diff --git a/lib/sqlalchemy/dialects/mysql/reflection.py b/lib/sqlalchemy/dialects/mysql/reflection.py
index 94b50ad4f..8aeb1dc96 100644
--- a/lib/sqlalchemy/dialects/mysql/reflection.py
+++ b/lib/sqlalchemy/dialects/mysql/reflection.py
@@ -249,6 +249,14 @@ class MySQLTableDefinitionParser(object):
         if comment is not None:
             comment = comment.replace("\\\\", "\\").replace("''", "'")
 
+        sqltext = spec.get("generated")
+        if sqltext is not None:
+            computed = dict(sqltext=sqltext)
+            persisted = spec.get("persistence")
+            if persisted is not None:
+                computed["persisted"] = persisted == "STORED"
+            col_kw["computed"] = computed
+
         col_d = dict(
             name=name, type=type_instance, default=default, comment=comment
         )
@@ -376,6 +384,8 @@ class MySQLTableDefinitionParser(object):
             r"(?:NULL|'(?:''|[^'])*'|[\w\(\)]+"
             r"(?: +ON UPDATE [\w\(\)]+)?)"
             r"))?"
+            r"(?: +(?:GENERATED ALWAYS)? ?AS +(?P<generated>\("
+            r".*\))? ?(?P<persistence>VIRTUAL|STORED)?)?"
             r"(?: +(?P<autoincr>AUTO_INCREMENT))?"
             r"(?: +COMMENT +'(?P<comment>(?:''|[^'])*)')?"
             r"(?: +COLUMN_FORMAT +(?P<colfmt>\w+))?"