From d1b76caaab598c7a3ea2aba1523f255f819c49ce Mon Sep 17 00:00:00 2001
From: Joakim Uddholm <tethik@gmail.com>
Date: Sun, 11 Feb 2018 17:27:57 +0100
Subject: [PATCH] Add scalar method to RecordCollection

---
 records.py            |  6 ++++++
 tests/test_records.py | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/records.py b/records.py
index 0fe09ca..3fedb0e 100644
--- a/records.py
+++ b/records.py
@@ -231,6 +231,12 @@ class RecordCollection(object):
         else:
             return record
 
+    def scalar(self, default=None):
+        """Returns the first column of the first row, or `default`."""
+        first = self.first()
+        return first[0] if first else default
+
+
 class Database(object):
     """A Database connection."""
 
diff --git a/tests/test_records.py b/tests/test_records.py
index 7e42731..5bfecf6 100644
--- a/tests/test_records.py
+++ b/tests/test_records.py
@@ -86,6 +86,24 @@ class TestRecordCollection:
         class Cheese(Exception): pass
         raises(Cheese, rows.first, Cheese('cheddar'))
 
+    # scalar
+
+    def test_scalar_returns_a_single_record(self):
+        rows = records.RecordCollection(IdRecord(i) for i in range(1))
+        assert rows.scalar() == 0
+
+    def test_scalar_defaults_to_None(self):
+        rows = records.RecordCollection(iter([]))
+        assert rows.scalar() is None
+
+    def test_scalar_default_is_overridable(self):
+        rows = records.RecordCollection(iter([]))
+        assert rows.scalar('Kaffe') == 'Kaffe'
+
+    def test_scalar_raises_when_more_than_first(self):
+        rows = records.RecordCollection(IdRecord(i) for i in range(3))
+        raises(ValueError, rows.scalar)
+
 
 class TestRecord: