ActiveRecord sum errors with postgresql

I am using AR's sum method for a query and seeing this error when using PostgreSQL:

PGError: ERROR: function sum(character varying) does not exist
LINE 1: SELECT sum("assets".asset_file_size) AS sum_asset_file_size ...
HINT: No function matches the given name and argument types. You might need to add explicit type casts.

SELECT sum("assets".asset_file_size) AS sum_asset_file_size FROM "assets" [0m

I am using the following in my code, which works with MySQL:

Asset.sum(:asset_file_size)

I 开发者_Python百科am trying to get a sum of the asset_file_size column.

What am I missing here?

OH.

In writing my question I worked out this issue.

I had accidentally made the column Varchar rather than an Integer. Hence the request to "explicitly type cast".

We apologise for the incovenience.