Class: BabySqueel::DSL

Inherits:
Relation show all
Defined in:
lib/baby_squeel/dsl.rb

Instance Attribute Summary

Attributes inherited from Relation

#_scope

Attributes inherited from Table

#_join, #_on, #_table

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Relation

#association, #initialize, #sift

Methods inherited from Table

#[], #_arel, #alias, #alias!, #find_alias, #initialize, #inner, #inner!, #on, #on!, #outer, #outer!

Constructor Details

This class inherits a constructor from BabySqueel::Relation

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(meth, *args, &block) ⇒ Object (private) 



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# File 'lib/baby_squeel/dsl.rb', line 108

def method_missing(meth, *args, &block)
  if !args.empty? && !block_given?
    func(meth, args)
  else
    super
  end
end

Class Method Details

.evaluate(scope, &block) ⇒ Object

Evaluates a block and unwraps the nodes



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# File 'lib/baby_squeel/dsl.rb', line 9

def evaluate(scope, &block)
  Nodes.unwrap evaluate!(scope, &block)
end

.evaluate!(scope, &block) ⇒ Object

Evaluates a block in the context of a DSL instance



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# File 'lib/baby_squeel/dsl.rb', line 14

def evaluate!(scope, &block)
  new(scope).evaluate(&block)
end

.evaluate_sifter(scope, *args, &block) ⇒ Object

Evaluates a block in the context of a new DSL instance and passes all arguments to the block.



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# File 'lib/baby_squeel/dsl.rb', line 20

def evaluate_sifter(scope, *args, &block)
  evaluate scope do |root|
    root.instance_exec(*args, &block)
  end
end

Instance Method Details

#_(expr) ⇒ Object

Create a Grouping node. This allows you to set balanced pairs of parentheses around your SQL.

Arguments

  • expr - The expression to group.

Example

Post.where.has{_([summary, description]).in(...)}
#=> SELECT "posts".* FROM "posts" WHERE ("posts"."summary", "posts"."description") IN (...)"
Post.select{[id, _(Comment.where.has{post_id == posts.id}.selecting{COUNT(id)})]}.as('comment_count')}
#=> SELECT "posts"."id", (SELECT COUNT("comments"."id") FROM "comments" WHERE "comments.post_id" = "posts"."id") AS "comment_count" FROM "posts"



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# File 'lib/baby_squeel/dsl.rb', line 40

def _(expr)
  expr = Arel.sql(expr.to_sql) if expr.is_a? ::ActiveRecord::Relation
  Nodes.wrap Arel::Nodes::Grouping.new(expr)
end

#evaluate(&block) ⇒ Object

Evaluates a DSL block. If arity is given, this method ‘yield` itself, rather than `instance_eval`.



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# File 'lib/baby_squeel/dsl.rb', line 98

def evaluate(&block)
  if block.arity.zero?
    instance_eval(&block)
  else
    yield(self)
  end
end

#exists(relation) ⇒ Object

Generate an EXISTS subselect from an ActiveRecord::Relation

Arguments

  • relation - An ActiveRecord::Relation

Example

Post.where.has { exists Post.where(id: 1) }



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# File 'lib/baby_squeel/dsl.rb', line 69

def exists(relation)
  func 'EXISTS', sql(relation.to_sql)
end

#func(name, *args) ⇒ Object

Create a SQL function. See Arel::Nodes::NamedFunction.

Arguments

  • name - The name of a SQL function (ex. coalesce).

  • args - The arguments to be passed to the SQL function.

Example

Post.selecting { func('coalesce', id, 1) }
#=> SELECT COALESCE("posts"."id", 1) FROM "posts"



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# File 'lib/baby_squeel/dsl.rb', line 56

def func(name, *args)
  Nodes.wrap Arel::Nodes::NamedFunction.new(name.to_s, args)
end

#not_exists(rel) ⇒ Object

Generate a NOT EXISTS subselect from an ActiveRecord::Relation

Arguments

  • relation - An ActiveRecord::Relation

Example

Post.where.has { not_exists Post.where(id: 1) }



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# File 'lib/baby_squeel/dsl.rb', line 82

def not_exists(rel)
  func 'NOT EXISTS', sql(rel.to_sql)
end

#quoted(value) ⇒ Object

Quotes a string and marks it as SQL



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# File 'lib/baby_squeel/dsl.rb', line 92

def quoted(value)
  sql _scope.connection.quote(value)
end

#sql(value) ⇒ Object

See Arel::sql



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# File 'lib/baby_squeel/dsl.rb', line 87

def sql(value)
  Nodes.wrap ::Arel.sql(value)
end