On Wednesday, April 16, 2014 9:24:05 PM UTC-7, Andrew Hacking wrote:
>
> Wondering how I can specify a computed model attribute which is always
> returned for my model.
>
> I would like to have an automatically computed sequence scoped on a column
> as follows:
>
> DB[:table].select_append{row_number(:over, partition: owner_id, order:
>> created_at){}.as(:item_number)}.from_self
>
>
> This returns the row_number as the item_number for all items scoped to
> owner_id, such that those numbers are monotonically increasing. It works
> perfectly.
>
> I have tried to add the following in my model class:
>
> set_dataset DB[:table].select_append{row_number(:over, partition:
>> owner_id, order: created_at){}.as(:item_number)}.from_self
>
>
> But I get the following error:
>
> sequel-4.6.0/lib/sequel/dataset/sql.rb:640:in `schema_and_table':
>> table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier,
>> or String (Sequel::Error)
>
> sequel-4.6.0/lib/sequel/database/schema_methods.rb:790:in
>> `schema_and_table'
>> sequel-4.6.0/lib/sequel/adapters/shared/postgres.rb:944:in `regclass_oid'
>> sequel-4.6.0/lib/sequel/adapters/shared/postgres.rb:340:in `indexes'
>> sequel-4.6.0/lib/sequel/plugins/auto_validations.rb:111:in
>> `setup_auto_validations'
>> sequel-4.6.0/lib/sequel/model/plugins.rb:44:in `block in
>> after_set_dataset'
>
>
> Any ideas how I can have my models include a (read only) attribute
> computed from a window function?
>
Well, from the backtrace, a quick fix would be to not use the
auto_validations plugin.
The patch below should fix things (assuming Google Groups doesn't mangle
it). I'll have to add a spec before I can commit it, though.
Thanks,
Jeremy
diff --git a/lib/sequel/plugins/auto_validations.rb
b/lib/sequel/plugins/auto_validations.rb
index e51b0f8..d40dc9d 100644
--- a/lib/sequel/plugins/auto_validations.rb
+++ b/lib/sequel/plugins/auto_validations.rb
@@ -107,8 +107,9 @@ module Sequel
@auto_validate_not_null_columns = not_null_cols -
Array(primary_key)
explicit_not_null_cols += Array(primary_key)
@auto_validate_explicit_not_null_columns =
explicit_not_null_cols.uniq
- @auto_validate_unique_columns = if db.supports_index_parsing?
- db.indexes(dataset.first_source_table).select{|name, idx|
idx[:unique] == true}.map{|name, idx| idx[:columns]}
+ table = dataset.first_source_table
+ @auto_validate_unique_columns = if db.supports_index_parsing? &&
[Symbol, SQL::QualifiedIdentifier, SQL::Identifier, String].any?{|c|
table.is_a?(c)}
+ db.indexes(table).select{|name, idx| idx[:unique] ==
true}.map{|name, idx| idx[:columns]}
else
[]
end
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