An ecto based Nested set model implementation for database
Add as_nested_set to your list of dependencies in mix.exs:
# use the stable version
def deps do
[{:as_nested_set, "~> 3.1", app: false}]
end
# use the latest version
def deps do
[{:as_nested_set, github: "https://github.com/secretworry/as_nested_set.git", app: false}]
end
To make use of as_nested_set your model has to have at least 4 fields: id, lft, rgt and parent_id. The name of those fields are configurable.
defmodule AsNestedSet.TestRepo.Migrations.MigrateAll do
use Ecto.Migration
def change do
create table(:taxons) do
add :name, :string
add :taxonomy_id, :id
add :parent_id, :id
add :lft, :integer
add :rgt, :integer
timestamps
end
end
endEnable the nested set functionality by use AsNestedSet on your model
defmodule AsNestedSet.Taxon do
use AsNestedSet, scope: [:taxonomy_id]
# ...
endYou can config the name of required field through attributes:
defmodule AsNestedSet.Taxon do
@right_column :right
@left_column :left
@node_id_column :node_id
@parent_id_column :pid
# ...
end@right_column: column name for right boundary (default tolft, since left is a reserved keyword for Mysql)@left_column: column name for left boundary (default torgt, reserved too)@node_id_column: specifies the name for the node id column (default toid, i.e. the id of the model, change this if you want to have a different id, or you id field is different)@parent_id_column: specifies the name for the parent id column (default toparent_id)
You can also pass following to modify its behavior:
defmodule AsNestedSet.Taxon do
use AsNestedSet, scope: [:taxonomy_id]
# ...
endscope: (required) a list of column names which restrict what is to be considered within the same tree(same scope).
Once you have set up you model, you can then
Add a new node
target = Repo.find!(Taxon, 1)
# add to left
%Taxon{name: "left", taxonomy_id: 1} |> AsNestedSet.create(target, :left) |> AsNestedSet.execute(TestRepo)
# add to right
%Taxon{name: "right", taxonomy_id: 1} |> AsNestedSet.create(target, :right) |> AsNestedSet.execute(TestRepo)
# add as first child
%Taxon{name: "child", taxonomy_id: 1} |> AsNestedSet.create(target, :child) |> AsNestedSet.execute(TestRepo)
# add as parent
%Taxon{name: "parent", taxonomy_id: 1} |> AsNestedSet.create(target, :parent) |> AsNestedSet.execute(TestRepo)
# add as root
%Taxon{name: "root", taxonomy_id: 1} |> AsNestedSet.create(:root) |> AsNestedSet.execute(TestRepo)
# move a node to a new position
node |> AsNestedSet.move(:root) |> AsNestedSet.execute(TestRepo)
node |> AsNestedSet.move(target, :left) |> AsNestedSet.execute(TestRepo)
node |> AsNestedSet.move(target, :right) |> AsNestedSet.execute(TestRepo)
node |> AsNestedSet.move(target, :child) |> AsNestedSet.execute(TestRepo)Remove a specified node and all its descendants
target = Repo.find!(Taxon, 1)
AsNestedSet.remove(target) |> AsNestedSet.execute(TestRepo)Query different nodes
# find all roots
AsNestedSet.roots(Taxon, %{taxonomy_id: 1}) |> AsNestedSet.execute(TestRepo)
# find all children of target
AsNestedSet.children(target) |> AsNestedSet.execute(TestRepo)
# find all the leaves for given scope
AsNestedSet.leaves(Taxon, %{taxonomy_id: 1}) |> AsNestedSet.execute(TestRepo)
# find all descendants
AsNestedSet.descendants(target) |> AsNestedSet.execute(TestRepo)
# include self
AsNestedSet.self_and_descendants(target) |> AsNestedSet.execute(TestRepo)
# find all ancestors
AsNestedSet.ancestors(target) |> AsNestedSet.execute(TestRepo)
#find all siblings (self included)
AsNestedSet.self_and_siblings(target) |> AsNestedSet.execute(TestRepo)Traverse the tree
# traverse a tree with 3 args post callback
AsNestedSet.traverse(Taxon, %{taxonomy_id}, context, fn node, context -> {node, context}, end, fn node, children, context -> {node, context} end) |> AsNestedSet.execute(TestRepo)
# traverse a tree with 2 args post callback
AsNestedSet.traverse(Taxon, %{taxonomy_id}, context, fn node, context -> {node, context}, end, fn node, context -> {node, context} end) |> AsNestedSet.execute(TestRepo)
# traverse a subtree with 3 args post callback
AsNestedSet.traverse(target, context, fn node, context -> {node, context}, end, fn node, children, context -> {node, context} end) |> AsNestedSet.execute(TestRepo)
# traverse a tree with 2 args post callback
AsNestedSet.traverse(target, context, fn node, context -> {node, context}, end, fn node, context -> {node, context} end) |> AsNestedSet.execute(TestRepo)
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