Column created as :decimal being treated as :integer on mysql with default: 0.0

[PlaidShirtPat]

Version information:
MYSQL DB version: 5.5.38-0ubuntu0.14.04.1
Rails version: 4.1.0
Ruby version: 2.1.0p0 (2013-12-25 revision 44422) [x86_64-linux]

I created a table with the following migration:
create_table "my_table", force: true do |t|
t.decimal "my_column", default: 0.0
end

When attempting to assign values to the column, the values would be treated as integers. In the MYSQL console, the column was reported as DECIMAL(10,0) with a default of 0. In the rails console, the column was reported as type :integer and acted as one.

No idea what caused this, but setting precision: 10, scale: 2 caused rails to treat the column as a :decimal again.

[sodabrew]

A decimal field with nothing past the decimal point sounds a lot like an integer. How do you expect this to function instead?

[PlaidShirtPat]

DECIMAL(10,0) acts like a decimal without the addition of default.

For example, with a table
create_table "my_table", force: true do |t|
t.decimal "my_column", default: 0.0
t.decimal "my_other_column"
end

Creates two DECIMAL(10,0) columns. If you look at the column types in rails, my_column will be :integer, while my_other_column will be :decimal.
Running the following on some MyTable record:

@my_table_record.update(my_column: 1.01, my_other_column: 1.01)
@my_table_record.my_column == 1
@my_table_record.my_other_column == 1.01
@my_table_record.my_column.is_a?(Integer)
@my_table_record.my_other_column.is_a?(BigDecimal)

I'm not sure why this is, but this is the behavior I am getting

[gmile]

I can confirm this issue.

1. 0.3.11 – working
2. 0.3.13 – (the one required by rails 4.1.x) not working

I'm checking using the following line:

ActiveRecord::Base.connection.exec_query('SELECT price FROM products WHERE product_id 1;')

The price column is DECIMAL(10, 2).

We're using CLUSTRIX MySQL, if that matters.

[sodabrew]

That helped narrow down the timeframe, and turned up this commit:

commit a099e55b678cec463b479c3589cb4dcfdcc837fc
Author: Wolfgang Kölbl <wok@iki.fi>
Date:   Tue Nov 22 21:13:43 2011 +0200

    Cast MYSQL_TYPE_DECIMAL AND MYSQL_TYPE_NEWDECIMAL to integer if number of decimals is 0

    Otherwise aggregate functions like SUM will produce decimals even when summing integers

diff --git a/ext/mysql2/result.c b/ext/mysql2/result.c
index af9fc67..d827f5b 100644
--- a/ext/mysql2/result.c
+++ b/ext/mysql2/result.c
@@ -237,7 +237,9 @@ static VALUE rb_mysql_result_fetch_row(VALUE self, ID db_timezone, ID app_timezo
           break;
         case MYSQL_TYPE_DECIMAL:    // DECIMAL or NUMERIC field
         case MYSQL_TYPE_NEWDECIMAL: // Precision math DECIMAL or NUMERIC field (MySQL 5.0.3 and up)
-          if (strtod(row[i], NULL) == 0.000000){
+          if (fields[i].decimals == 0) {
+            val = rb_cstr2inum(row[i], 10);
+          } else if (strtod(row[i], NULL) == 0.000000){
             val = rb_funcall(cBigDecimal, intern_new, 1, opt_decimal_zero);
           }else{
             val = rb_funcall(cBigDecimal, intern_new, 1, rb_str_new(row[i], fieldLengths[i]));

[gmile]

@sodabrew fixed in #563