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YAML Config Syntax

The YAML format is simpler than the JSON one, and is the format used by the osm-fieldwork project and the FMTM project for use in field data collection. This is used for canned datbase queires that are used to make data extracts for ODK Collect.

select

If let blank, the tags in the keep section and where sections are used to return a subset of tags & values, instead of all the tags.

from

This is a list of the database tables. By default these are the tables used in the custom database schema created with the included raw.lua script for osm2pgsql.

The tables are:

  • nodes
  • relations
  • ways_line
  • ways_poly

where

The where section is a bit more complicated because we need to support a mix of OR and AND arguments. There is a limit to how complicated this can get, but sometimes it's easier to just do a little manual cleanup with the results.

The syntax is the same for the join_or keyword, or the join_and keyword. If you want to query for any value of the keyword, as not_null, which later gets turned into IS NOT NULL in SQL. It has a value associated with the keyword, then that is the only value searching for.

keep

The tags in the keep field are the ones we want returned in the SQL query, but aren't part of the where section. Othwise they fail to appear in the results.

Example

This config file is for building extracts.

select:
  - name: title
from:
 - nodes
 - ways_poly
where:
  tags:
 - join_or:
  - { building: yes, amenity: not null }
 - join_and:
  - { building:material: wood }
keep:
 - building:levels
 - building:material
 - roof:material
 - roof:shape
 - roof:levels
 - cusine
 - convenience
 - diesel
 - version

That then generates a list of SQL queries, one for each table in the database. Note that the table name has been changed to have _view appended. This is because a view has been created from each table using the project boundary.

SELECT ST_AsText(geom), osm_id, version, tags->>'building:levels',
 tags->>'building:material', tags->>'roof:material',
 tags->>'roof:shape', tags->>'roof:levels', tags->>'cusine',
 tags->>'convenience', tags->>'diesel', tags->>'version',
 tags->>'building', tags->>'amenity',
 tags->>'building:material' FROM ways_view WHERE (
 tags->>'building'='yes' OR tags->>'amenity' IS NOT NULL)  AND
 tags->>'building:material'='wood'

Last update: July 10, 2024