Changes between Version 5 and Version 6 of S3/S3Hierarchy

Timestamp:

05/21/14 21:26:31 (12 years ago)

Author:

Dominic König

Comment:

--

S3/S3Hierarchy

@@ -55 +55 @@
 }}}
 
-== Connecting to the Hierarchy ==
-
-  - ''tbw''
+== Subset Definition ==
+
+To perform lookups in the hierarchy, you need to define a subset, which is an S3Hierarchy instance.
+
+With the tablename as only parameter, the subset would include all records in the hierarchical table (...which are accessible for the user):
+
+{{{#!python
+subset = S3Hierarchy("hierarchical_type_table")
+}}}
+
+To filter the records, a filter query can be specified as keyword parameter:
+
+{{{#!python
+query = (FS("filter_field") == 5)
+subset = S3Hierarchy("hierarchical_type_table, filter=query)
+}}}
+
+== Performing Lookups ==
+
+All lookup attributes or methods of the subset use node IDs. 
+
+The node IDs are either the record IDs (for simple self-reference) or the super-IDs (for super-entity self-reference) of the records in the subset.
+
+All lookup attributes and methods return either a single node ID (long), or a '''set''' of node IDs. The only exception is path() which returns an ordered list of node IDs.
+
+=== Root Nodes ===
+
+To get all root nodes of the subset, use:
+
+{{{#!python
+# Returns a set of node IDs
+root_nodes = subset.roots
+}}}
+
+To get the root node for a particular node, use:
+
+{{{#!python
+# Returns the root node ID for node_id (or node_id if it is a root node itself)
+root = subset.root(node_id)
+}}}
+
+=== Child Nodes ===
+
+To get all child nodes of a node, use:
+
+{{{#!python
+# Returns the first generation of child nodes for node_id
+children = subset.children(node_id)
+}}}
+
+To get all descendants of a node, use:
+
+{{{#!python
+# Returns all descendant nodes (any generation) for node_id
+children = subset.findall(node_id)
+}}}
+
+It is possible to use findall to get a union set of descendants for multiple parent nodes:
+{{{#!python
+# Returns all descendants in all specified nodes
+children = subset.findall((node_id_1, node_id_2, node_id_3))
+}}}
+
+=== Parent Nodes ===
+
+To get the parent node ID for a node, use:
+
+{{{#!python
+# Returns the parent node ID for node_id (or None if node_id is a root node)
+parent = subset.parent(node_id)
+}}}
+
+=== Sibling Nodes ===
+
+To get all sibling node IDs for a node, use:
+
+{{{#!python
+# Returns all sibling node IDs for node_id
+siblings = subset.siblings(node_id)
+}}}
+
+This does not normally return node_id itself, unless you specify inclusive=True:
+
+{{{#!python
+# Returns all sibling node IDs for node_id - including node_id itself
+siblings = subset.siblings(node_id, inclusive=True)
+}}}
+
+=== Path ===
+
+The path of a node is an ordered list of all generations of parent node IDs from the root node down to the node itself. It can be requested by:
+
+{{{#!python
+# Returns the path of a node (root node first) as ordered list
+path = subset.path(node_id)
+}}}
+
+== Using categories ==
+
+Categories can be used to classify nodes "horizontally", e.g. to indicate a hierarchy "level". To use them with the hierarchy toolkit, an additional category-field must be defined in the hierarchy configuration:
+
+{{{#!python
+    self.configure(tablename, hierarchy=(parent_field, category_field))
+}}}
+
+Categories are neither managed nor inferred by the hierarchy toolkit, but they can be used to filter the lookup axis.
+
+=== Filtering the Lookup Axis ===
+
+This is useful e.g. to find all descendants of a node of a specific category:
+
+{{{#!python
+# Define a hierarchy of locations with "parent" as parent-reference and "level" as category
+subset = S3Hierarchy("gis_location", hierarchy=("parent", "level"))
+
+# Lookup all descendants of location #3 with category "L3"
+communes = subset.findall(3, category="L3", inclusive=True)
+}}}
+
+When performing a root lookup, we may be interested in the closest parent of a particular category rather than the absolute root:
+
+{{{#!python
+# Lookup the closest "L1" parent of location #454
+state = subset.root(454, category="L1")
+}}}
+
+This does also work with path lookups:
+
+{{{#!python
+# Lookup the path of location #378 down from the closest "L1" parent
+path = subset.path(378, category="L1")
+}}}
+
+The category parameter can be used analogously with the children() and siblings() methods.
+
+=== Looking up the Category of a Node ===
+
+To lookup the category of a node, use:
+
+{{{#!python
+# Returns the category for node_id (e.g. "L1")
+category = subset.category(node_id)
+}}}
+
+To get the category of each node in the result of the parent(), root(), path(), children(), findall(), or siblings() methods, use the classify-flag like:
+
+{{{#!python
+# Returns the children of location #328 as set of tuples like: set([(367, "L3"), (368, "L3")])
+children = subset.children(328, classify=True)
+}}}
+