DSL for Table footer

[Fivell]

Hello @timoschilling , @seanlinsley , Hello contributors.
One of my customer asked me to display total sum for some of columns in table footer crossing all the pages. I looked at source code and found out there was nothing in AA working out of the box for implementing such I small feature.

So I patched some classes and forgot about it. But now I need to do it again in another project.
Screenshot to clarify

How this was done.

1. I patched AA internals for supporting tfoot tag in `index_as_tableandtable_for``
   source -> https://gist.github.com/Fivell/d45653841cee22a890f5
2. after this I was able to do

index  has_footer: true  do
    selectable_column
    actions
    id_column
    column :balance , footer_proc: ->(collection) {
           collection.except(:limit, :offset).sum(:balance)
         }
end   

Problems with such hack

1. every footer ceil perform new sql query (this is bad if you have many numeric columns and want to display sum or avg or max of each of them), the much more better way is to calculate aggregations for each of column with 1 sql query
2. DSL is ugly, DSL should be much more cleaner for such a standard feature.

Any ideas how to improve this and make it part of AA?

[ccallebs]

If we make some assumptions about what kind of data will be available in a table footer, the DSL could be simplified drastically. For your example:

column :balance, sum: true

We could also offer mean/median/etc.

[timoschilling]

👍 I like the idea and will think about it

[timoschilling]

@ccallebs your idea is not bad, but it's not generic. We need to map each kind of SQL Function to a attribute.
This is more generic:

column :balance, footer: "SUM(balance)"

[Fivell]

@timoschilling ,
footer: "SUM(balance)" <-- this can be not enough , we should also have possibility to use view helpers(status tags , money formatting etc...), decorators , etc, in footer ceil like in simple table cell

[timoschilling]

@Fivell sure, that was only 'equal' to column :balance, sum: true.

[Fivell]

👍 hope we'll add this feature soon

[dmitry]

To make it possible to use formatting in the footer I suggest adding the :footer_formatting attribute for column DSL.

[Fivell]

after few modifications, I fix problem with multiple queries, now I use it like

index  footer_data: ->(collection){collection.except(:includes, :limit, :offset).reorder("").select("sum(amount) as total_amount").to_a.first}  do

     id_column
     column :amount, footer: -> {
           @footer_data[:total_amount]
         }
     column :account
     column :notes
     column :created_at

  end

[timoschilling]

footer_data should be a proc argument and not a global method.

I don't like the API with so many symbol: proc{} args.

This should work:

column :amount, footer: &:total_amount

[Fivell]

@timoschilling , this doesn't work

 syntax error, unexpected &

[Fivell]

I don't like DSL with many procs too, so maybe we might think about other way
something like

footer   ->(collection) {collection.totals }, as: :table do 
   column :total, for: :amount do |row|
       number_to_currency(row.total) 
   end
end

then we need

1. multiple indexes footer as: :table (:blog, :grid, etc)
2. scoped_collection proc for footer ->(collection) {collection.totals }
3. helpers can be used number_to_currency(row.total)
4. each column should know parent column for: :amount

so DSL args
proc for collection, options , &block

[fjosimovski]

Hello @timoschilling . Is there any progress (plan) related to this issue?

[timoschilling]

@fwebs no

[tamvm]

Other way to customize collection and add mock object for footer row like:

table_for bank_clients + [OpenStruct.new(balance: bank_clients.sum(:balance))] do

[pundit]

Hi Authors, commentors,
@timoschilling will this feature be implemented in the future?

[timoschilling]

@pundit maybe, all depends on whether someone the time it takes to build

[victorlcampos]

@timoschilling, this is a very good idea, whats the problem with original solution? ugly dsl is better than no dsl at all. And a footer_proc is not ugly for me, it permits calculate custom things like "Weighted Average" and so one.

[qiwu7]

any progress on this?

[dhurba87]

Any progress on this?