From c611ed80d2e9f721fc7848fd74e6e6baebe5adde Mon Sep 17 00:00:00 2001
From: Simon Willison <simonw@eventbrite.com>
Date: Tue, 31 Jul 2018 18:31:29 -0700
Subject: [PATCH] .indexes property for introspecting indexes

---
 docs/table.rst           | 10 ++++++++++
 sqlite_utils/db.py       | 13 +++++++++++++
 tests/test_introspect.py | 24 +++++++++++++++++++++++-
 3 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/docs/table.rst b/docs/table.rst
index 5fa7260..4bed6b9 100644
--- a/docs/table.rst
+++ b/docs/table.rst
@@ -167,6 +167,16 @@ The ``.schema`` property outputs the table's schema as a SQL string::
         FOREIGN KEY ("qCareAssistant") REFERENCES [qCareAssistant](id),
         FOREIGN KEY ("qLegalStatus") REFERENCES [qLegalStatus](id))
 
+The ``.indexes`` property shows you all indexes created for a table::
+
+    >>> db["Street_Tree_List"].indexes
+    [Index(seq=0, name='"Street_Tree_List_qLegalStatus"', unique=0, origin='c', partial=0, columns=['qLegalStatus']),
+     Index(seq=1, name='"Street_Tree_List_qCareAssistant"', unique=0, origin='c', partial=0, columns=['qCareAssistant']),
+     Index(seq=2, name='"Street_Tree_List_qSiteInfo"', unique=0, origin='c', partial=0, columns=['qSiteInfo']),
+     Index(seq=3, name='"Street_Tree_List_qSpecies"', unique=0, origin='c', partial=0, columns=['qSpecies']),
+     Index(seq=4, name='"Street_Tree_List_qCaretaker"', unique=0, origin='c', partial=0, columns=['qCaretaker']),
+     Index(seq=5, name='"Street_Tree_List_PlantType"', unique=0, origin='c', partial=0, columns=['PlantType'])]
+
 Enabling full-text search
 =========================
 
diff --git a/sqlite_utils/db.py b/sqlite_utils/db.py
index 2d6c30a..3f922c0 100644
--- a/sqlite_utils/db.py
+++ b/sqlite_utils/db.py
@@ -8,6 +8,7 @@ Column = namedtuple(
 ForeignKey = namedtuple(
     "ForeignKey", ("table", "column", "other_table", "other_column")
 )
+Index = namedtuple("Index", ("seq", "name", "unique", "origin", "partial", "columns"))
 
 
 class Database:
@@ -122,6 +123,18 @@ class Table:
             "select sql from sqlite_master where name = ?", (self.name,)
         ).fetchone()[0]
 
+    @property
+    def indexes(self):
+        sql = "select * from pragma_index_list(?)"
+        indexes = []
+        for row in list(self.db.conn.execute(sql, (self.name,)).fetchall()):
+            column_sql = "select name from pragma_index_info(?) order by seqno"
+            columns = [
+                r[0] for r in self.db.conn.execute(column_sql, (row[1],)).fetchall()
+            ]
+            indexes.append(Index(*(row + (columns,))))
+        return indexes
+
     def create(self, columns, pk=None, foreign_keys=None):
         columns = {name: value for (name, value) in columns.items()}
         self.db.create_table(self.name, columns, pk=pk, foreign_keys=foreign_keys)
diff --git a/tests/test_introspect.py b/tests/test_introspect.py
index fc1f226..b06ea91 100644
--- a/tests/test_introspect.py
+++ b/tests/test_introspect.py
@@ -1,4 +1,5 @@
-from .fixtures import existing_db
+from .fixtures import existing_db, fresh_db
+from sqlite_utils.db import Index
 
 
 def test_table_names(existing_db):
@@ -27,3 +28,24 @@ def test_schema(existing_db):
 
 def test_table_repr(existing_db):
     assert "<Table foo>" == repr(existing_db["foo"])
+
+
+def test_indexes(fresh_db):
+    fresh_db.conn.executescript(
+        """
+        create table Gosh (c1 text, c2 text, c3 text);
+        create index Gosh_c1 on Gosh(c1);
+        create index Gosh_c2c3 on Gosh(c2, c3);
+    """
+    )
+    assert [
+        Index(
+            seq=0,
+            name="Gosh_c2c3",
+            unique=0,
+            origin="c",
+            partial=0,
+            columns=["c2", "c3"],
+        ),
+        Index(seq=1, name="Gosh_c1", unique=0, origin="c", partial=0, columns=["c1"]),
+    ] == fresh_db["Gosh"].indexes