stefankroes/ancestry

Organise ActiveRecord model into a tree structure

Nathan Flood

@npflood

The repository readme says that the gem is compatible with Rails 3, any known issues working with Rails 4?

arjan0307

@arjan0307

Nope, it should work fine.

Nathan Flood

@npflood

Thanks arjan, so far everything is going fine.

nchafai

@nchafai

Hi. Ancestry provides scopes like "ancestors_of, subtree_of", etc. But these scopes are Class ones, and can not be chained to other scopes.
For instance, if i have "scope :open, :conditions => 'open = 1'", i cannot chain it with Ancestry scopes like : "Model.open.subtree".

Is there a way to perform such operation?

arjan0307

@arjan0307

Does it work the other way around?

Model.subtree.open

nchafai

@nchafai

No. The scope "subtree" only exists as an instance method, so that i can only get the subtree of one node.

arjan0307

@arjan0307

True, so what is it that you are trying to achieve with your original question?

You want all the models that are "open"

but what should adding subtree do?

nchafai

@nchafai

I have a scope like this : named_scope :open, :conditions => "brand is not null", and i would like to select all models that are subtree of this scope.
Currently, i have to build a loop and selecting all subtrees of each model ; that is not efficient at all (n requests rather than 1).

I found an other solution, that is not perfect since its not really chainable, and looks like this :

named_scope :branded, lambda {{
:joins => "LEFT JOIN groups AS ancestors ON (
groups.ancestry = ancestors.id
OR groups.ancestry LIKE CONCAT(ancestors.id,'/%')
OR groups.ancestry LIKE CONCAT('%/', CONCAT(ancestors.id,'/%'))
OR groups.ancestry LIKE CONCAT('%/',ancestors.id)
OR ancestors.id = groups.id
)",
:conditions => '(ancestors.brand IS NOT NULL AND ancestors.brand !="")'
}}

I wished Ancestry provided real scopes that are chainables and did this job.

Matt Hink

@mhink

So, quick question. How well does Ancestry play with the 'ltree' column type in Postgres?

arjan0307

@arjan0307

@mhink Late answer. AFAIK it doesn't. Ancestry utilizes a string column and stores paths like ":parent_id/:grand_parent_id". It constructs where queries in Arel that match forementioned string. In theory you could add very basic support for LTREE by using ltree2text when LTREE is used instead of a string column, but that would only slow performance. Adding full support for LTREE could be done as well, but would require some more work. Feel free to create a pull-request if you are up for it.

Jimmy Baker

@jimmybaker

Does anyone know how to property set a parent when using fixtures in rails 4?

Matthew Brown

@matthewbga

Ancestry has been extremely useful since rails 1.2.6 for me. Is it still alive? I see we have glitter here, so that's a good sign....

Matthew Brown

@matthewbga

gitter*

Rishav Paul

@rpaul93

Hi, how can I order siblings in ancestry?

Brandon Lawrence

@Brantron

whats the syntax for adding an ancester to an object on creation?

I tried Product.create(:name => 'Cheap Koozies', :parent => 'Drinkware') but it didn't work. The Drinkware object already exists

nchafai

@nchafai

@jimmybaker In rails 2, i do this :
grand_parent:
name: Grand parent

parent:
name: Parent
ancestry: '<%= Fixtures.identify(:grand_parent) %>'

child:
ancestry: '<%= Fixtures.identify(:grand_parent) %>/<%= Fixtures.identify(:parent) %>'

Kyle Tully

@kyletully

Hi All,
Am using Ancestry inside a mountable engine on rails 4.2.2 and receive the following error "undefined local variable or method `has_ancestry' when adding "has_ancestry" to the model.rb file

Is there anything different needed when installing Ancestry within a mountable engine?

Oleksandr Bratashov

@abratashov

Hello guys, could you help me with some question, when i setup ancestry for my model Category and create 4 items wich includes each other, last item has depth 2, but it shuld be 4 http://prntscr.com/br8hww

A - 1
B - 2
C - 2 (should be 3)
D - 2 (should be 4)

https://github.com/stefankroes/ancestry

Denny Mueller

@dennym

Hey anyone available for a second?

Jason Frey

@Fryguy

what's up @dennym ?

Tim Wisniewski

@timwis

Hi all 👋 I’d like to leverage recursive window queries (aka common table expressions, a modern feature of Postgres and MySQL) for my nesting/ancestry, to optimise query performance. Has anyone heard of a way to do that in rails?

Jason Frey

@Fryguy

@timwis I haven't seen anything gemwise, personally, but there is this: https://sonnym.github.io/2017/06/05/common-table-expressions-in-activerecord-a-case-study-of-quantiles/

and this - rails/rails#37944

and - rails/rails#37973

Tim Wisniewski

@timwis

@Fryguy thanks, I came across those as well. Given how complex those Arel bits look, it seems like a great candidate for a module :/

Wish I knew enough about rails modules to build it myself 🤔

Tim Wisniewski

@timwis

Oh my gosh, I just realised that ancestry uses the same exact approach that I've been using in my app for 6 years! That means I can potentialy migrate to it without actually changing my database :O Only difference is my paths look like /1/3/5/ (with leading and trailing slashes)

Julio Papel

@JulioPapel

Hi guys, I added ancestry to my Category Model and it works nicely on the console, but to show a pull_down menu and update the parent of that category. I'm doing something like this: = fae_pulldown f, :parent, size: 'short', collection: Category.roots.order(:name) but it can't find the parent. if I use :ancestry it shows the form but cant submit! Any Ideas?

Eric Pugh

@epugh

So... Any one have a recommendation for a front end tool for displaying a has_ancestry graph? Hoping to not start at the basics with D3 ;-)

Eric Pugh

@epugh

how do I associate two existing objects togetehr? try_one.children << try_two was my first guess!

  try_two.parent = try_one
  try_two.save!

  assert_equal try_one.children.first, try_two

Eric Pugh

@epugh

anyone done anything with DOT language and this gem?

Jason Frey

@Fryguy

If you don't mind querying the whole thing up front, you can print it rather easily be using subtree.arrange, then walking it...

def print_objs(subtree, indent = '')
  subtree = subtree.sort_by { |rec, _children| rec.name }
  subtree.each do |rec, children|
    puts "#{indent}- #{rec.name} (#{rec.id})"
    print_objs(children, "  #{indent}")
  end
end

roots = Model.roots.sort_by(&:name)
roots.each do |root|
  print_objs(root.subtree.arrange)
  puts("\n")
end

Keenan Brock

@kbrock

thanks jason. that looks slick

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