view_information should raise instead of warn

[coldnebo]

In SchemaStatements#view_information line 337:

view_info[:VIEW_DEFINITION] = begin
    select_values("EXEC sp_helptext #{quote_table_name(table_name)}", 'SCHEMA').join
  rescue
    warn "No view definition found, possible permissions problem.\nPlease run GRANT VIEW DEFINITION TO your_user;"
    nil
  end

The condition indicated by the warn is serious enough to require a raise instead.

For example, one of our read-only models uses a view. Since there is no migration, it is critical that permission to run sp_helptext is granted, but since this assignment returns nil, we get a meaningless error somewhere later in Model.find():

ReportDetails view exception: undefined method `match' for nil:NilClass 

This error comes from deep in the rails stack without providing a clear indication of what happened. For the curious it's caused by the function views_real_column_name in line 351 in schema_statements.rb which is invoked during find():

match_data = view_definition.match(/([\w-]*)\s+as\s+#{column_name}/im)

[metaskills]

FWIW, I have had previous issue that talked about not requiring sp_helptext since most DBAs do not like to give the "application" that much permission. I think this is why it is only a warning.

[coldnebo]

Yes, that's been our experience too (re permissions). Is there an alternative way to initialize the view_definition, say from a hardcoded schema, or from the results of a query? While we may not always have perms, we do always know what the column names should be for a given query.

[coldnebo]

After thinking about this some more, it seems that another way to solve this problem is to protect against the view_definition being accessed when nil. See the pull request above for a possible fix.