amsterdam-schema-tools 0.17.8

Tools to work with Amsterdam schema.

amsterdam-schema-tools

Set of libraries and tools to work with Amsterdam schema.

Install the package with: pip install amsterdam-schema-tools

Currently, the following cli commands are available:

• schema import events
• schema import ndjson
• schema show schema
• schema show tablenames
• schema introspect db
• schema introspect geojson *.geojson
• schema validate
• schema permissions apply

The tools expect either a DATABASE_URL environment variable or a command-line option --db-url with a DSN.

The output is a json-schema output according to the Amsterdam schemas definition for the tables that are being processed.

Generate amsterdam schema from existing database tables

The --prefix argument controls whether table prefixes are removed in the schema, because that is required for Django models.

As example we can generate a BAG schema. Point DATABASE_URL to bag_v11 database and then run :

schema show tablenames | sort | awk '/^bag_/{print}' | xargs schema introspect db bag --prefix bag_ | jq

The jq formats it nicely and it can be redirected to the correct directory in the schemas repository directly.

Express amsterdam schema information in relational tables

Amsterdam schema is expressed as jsonschema. However, to make it easier for people with a more relational mind- or toolset it is possible to express amsterdam schema as a set of relational tables. These tables are meta_dataset, meta_table and meta_field.

It is possible to convert a jsonschema into the relational table structure and vice-versa.

This command converts a dataset from an existing dataset in jsonschema format:

schema import schema <id of dataset>

To convert from relational tables back to jsonschema:

schema show schema <id of dataset>

Generating amsterdam schema from existing GeoJSON files

The following command can be used to inspect and import the GeoJSON files:

schema introspect geojson <dataset-id> *.geojson > schema.json
edit schema.json  # fine-tune the table names
schema import geojson schema.json <table1> file1.geojson
schema import geojson schema.json <table2> file2.geojson

Importing GOB events

The schematools library has a module that read GOB events into database tables that are defines by an Amsterdam schema. This module can be used to read GOB events from a Kafka stream. It is also possible to read GOB events from a batch file with line-separeted events using:

schema import events <path-to-dataset> <path-to-file-with-events>