Class: ConceptQL::Operators::First
- Inherits:
-
Occurrence
- Object
- Operator
- Occurrence
- ConceptQL::Operators::First
- Defined in:
- lib/conceptql/operators/first.rb
Overview
Represents a operator that will grab the first occurrence of something
The operator treats all streams as a single, large stream. It partitions that larget stream by person_id, then sorts within those groupings by start_date and then select at most one row per person, regardless of how many different types of streams enter the operator
If two rows have the same start_date, the order of their ranking is arbitrary
If we ask for the first occurrence of something and a person has no occurrences, this operator returns nothing for that person
Instance Attribute Summary
Attributes inherited from Operator
#arguments, #errors, #nodifier, #options, #upstreams, #values
Instance Method Summary collapse
Methods inherited from Occurrence
#occurrences, #query, #query_cols
Methods inherited from Operator
#annotate, #cast_column, #code_list, codes_should_match, #columns, #create_upstreams, #data_model, #database_type, default_query_columns, #domains, #dup_values, #dynamic_columns, #evaluate, inherited, #initialize, #inspect, #label, new, #operator_name, #optimized, query_columns, register, require_column, #required_columns, #scope, #select_it, #setup_select, #sql, #stream, #to_op, #unionable?, #upstreams_valid?, #valid?
Methods included from Metadatable
#allows_many_upstreams, #allows_one_upstream, #argument, #auto_label, #basic_type, #category, #derive_metadata_from_validations, #desc, #domains, #get_desc, #humanized_class_name, #inherited, #just_class_name, #no_desc, #option, #predominant_domains, #pref_name, #preferred_name, #reset_categories, #standard_description, #to_metadata, #validate_at_least_one_upstream_to_metadata, #validate_at_most_one_upstream_to_metadata, #validate_no_arguments_to_metadata, #validate_no_upstreams_to_metadata, #validate_one_upstream_to_metadata, #validate_required_options_to_metadata, #warn_about_missing_metadata
Constructor Details
This class inherits a constructor from ConceptQL::Operators::Operator
Instance Method Details
#occurrence ⇒ Object
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# File 'lib/conceptql/operators/first.rb', line 22 def occurrence 1 end |