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authorCarlos Antonio da Silva <carlosantoniodasilva@gmail.com>2012-06-22 09:30:00 -0300
committerCarlos Antonio da Silva <carlosantoniodasilva@gmail.com>2012-06-22 09:32:41 -0300
commite5cd300becab8e05f4568a402e3fce4f4497733a (patch)
tree238a37bc01acbcebd7a463fc08ba8e813a4d79c5 /guides/source
parent6aae17e85613fe8c2816ba278f9348f168692479 (diff)
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Add changelog entry and guide updates for pluck with multiple columns
Diffstat (limited to 'guides/source')
-rw-r--r--guides/source/active_record_querying.textile22
1 files changed, 16 insertions, 6 deletions
diff --git a/guides/source/active_record_querying.textile b/guides/source/active_record_querying.textile
index 4b14671efc..101988c59e 100644
--- a/guides/source/active_record_querying.textile
+++ b/guides/source/active_record_querying.textile
@@ -609,8 +609,8 @@ And this will give you a single +Order+ object for each date where there are ord
The SQL that would be executed would be something like this:
<sql>
-SELECT date(created_at) as ordered_date, sum(price) as total_price
-FROM orders
+SELECT date(created_at) as ordered_date, sum(price) as total_price
+FROM orders
GROUP BY date(created_at)
</sql>
@@ -627,9 +627,9 @@ Order.select("date(created_at) as ordered_date, sum(price) as total_price").grou
The SQL that would be executed would be something like this:
<sql>
-SELECT date(created_at) as ordered_date, sum(price) as total_price
-FROM orders
-GROUP BY date(created_at)
+SELECT date(created_at) as ordered_date, sum(price) as total_price
+FROM orders
+GROUP BY date(created_at)
HAVING sum(price) > 100
</sql>
@@ -1286,26 +1286,36 @@ Client.connection.select_all("SELECT * FROM clients WHERE id = '1'")
h3. +pluck+
-<tt>pluck</tt> can be used to query a single column from the underlying table of a model. It accepts a column name as argument and returns an array of values of the specified column with the corresponding data type.
+<tt>pluck</tt> can be used to query a single or multiple columns from the underlying table of a model. It accepts a list of column names as argument and returns an array of values of the specified columns with the corresponding data type.
<ruby>
Client.where(:active => true).pluck(:id)
# SELECT id FROM clients WHERE active = 1
+# => [1, 2, 3]
Client.uniq.pluck(:role)
# SELECT DISTINCT role FROM clients
+# => ['admin', 'member', 'guest']
+
+Client.pluck(:id, :name)
+# SELECT clients.id, clients.name FROM clients
+# => [[1, 'David'], [2, 'Jeremy'], [3, 'Jose']]
</ruby>
+pluck+ makes it possible to replace code like
<ruby>
Client.select(:id).map { |c| c.id }
+# or
+Client.select(:id).map { |c| [c.id, c.name] }
</ruby>
with
<ruby>
Client.pluck(:id)
+# or
+Client.pluck(:id, :name)
</ruby>
h3. +ids+