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https://github.com/dazuma/activerecord-postgis-adapter
ActiveRecord connection adapter for PostGIS, based on postgresql and rgeo
https://github.com/dazuma/activerecord-postgis-adapter
activerecord postgis postgresql rails rgeo ruby
Last synced: 3 days ago
JSON representation
ActiveRecord connection adapter for PostGIS, based on postgresql and rgeo
- Host: GitHub
- URL: https://github.com/dazuma/activerecord-postgis-adapter
- Owner: rgeo
- License: other
- Created: 2010-12-07T01:47:35.000Z (almost 14 years ago)
- Default Branch: master
- Last Pushed: 2024-10-17T08:40:41.000Z (28 days ago)
- Last Synced: 2024-10-29T13:50:58.107Z (16 days ago)
- Topics: activerecord, postgis, postgresql, rails, rgeo, ruby
- Language: Ruby
- Homepage:
- Size: 1.2 MB
- Stars: 870
- Watchers: 31
- Forks: 237
- Open Issues: 17
-
Metadata Files:
- Readme: README.md
- Changelog: History.md
- Contributing: CONTRIBUTING.md
- License: LICENSE.txt
Awesome Lists containing this project
- awesome-ruby-toolbox - activerecord-postgis-adapter - ActiveRecord connection adapter for PostGIS. It is based on the stock PostgreSQL adapter, and adds built-in support for the spatial extensions provided by PostGIS. It uses the RGeo library to represent spatial data in Ruby. (Time & Space / Geocoding & Maps)
README
# ActiveRecord PostGIS Adapter
[](https://badge.fury.io/rb/activerecord-postgis-adapter)
[](https://codeclimate.com/github/rgeo/activerecord-postgis-adapter/maintainability)
The activerecord-postgis-adapter provides access to features
of the PostGIS geospatial database from ActiveRecord. It extends
the standard postgresql adapter to provide support for the spatial data types
and features added by the PostGIS extension. It uses the
[RGeo](https://github.com/rgeo/rgeo) library to represent spatial data in Ruby.
## Overview
The adapter provides three basic capabilities:
First, it provides _spatial migrations_. It extends the ActiveRecord migration
syntax to support creating spatially-typed columns and spatial indexes. You
can control the various PostGIS-provided attributes such as SRID, dimension,
and geographic vs geometric math.
Second, it recognizes spatial types and casts them properly to RGeo geometry
objects. The adapter can configure these objects automatically based on the
SRID and dimension in the database table, or you can tell it to convert the
data to a different form. You can also set attribute data using WKT format.
Third, it lets you include simple spatial data in queries. WKT format data and
RGeo objects can be embedded in where clauses.
## Install
The adapter requires PostgreSQL 9.0+ and PostGIS 2.4+.
### Installing PostGIS
Here are common methods for installing PostGIS, but more detailed methods can be found on the [installation guide](https://postgis.net/install/).
#### MacOS
```sh
brew install postgis
```
#### Ubuntu/Debian
```sh
sudo apt-get install postgis postgresql-16-postgis-3
```
#### Windows
PostGIS is likely available as an optional package via your Postgresql installer. If not, refer to the installation guide.
Gemfile:
```ruby
gem 'activerecord-postgis-adapter'
```
#### Version 10.x supports ActiveRecord 7.2
```
ActiveRecord 7.2
Ruby 3.1.0+
PostGIS 2.0+
```
#### Version 9.x supports ActiveRecord 7.1
```
ActiveRecord 7.1
Ruby 3.0.0+
PostGIS 2.0+
```
#### Version 8.x supports ActiveRecord 7.0
Requirements:
```
ActiveRecord 7.0
Ruby 2.7.0+
PostGIS 2.0+
```
#### Version 7.x supports ActiveRecord 6.1
Requirements:
```
ActiveRecord 6.1
Ruby 2.5.0+, JRuby
PostGIS 2.0+
```
#### Version 6.x supports ActiveRecord 6.0
Requirements:
```
ActiveRecord 6.0
Ruby 2.5.0+, JRuby
PostGIS 2.0+
```
#### Version 5.x supports ActiveRecord 5.1 and 5.2
Requirements:
```
ActiveRecord 5.1 or 5.2
Ruby 2.2.2+, JRuby
PostGIS 2.0+
```
#### Version 4.x supports ActiveRecord 5.0
Requirements:
```
ActiveRecord 5.0
Ruby 2.2.2+, JRuby
PostGIS 2.0+
```
#### Version 3.x supports ActiveRecord 4.2
Requirements:
```
ActiveRecord 4.2
Ruby 1.9.3+, JRuby
PostGIS 2.0+
```
#### Version 2.x supports ActiveRecord 4.0.x and 4.1.x
_If you are using version 2.x, you should read [the version 2.x README](https://github.com/rgeo/activerecord-postgis-adapter/blob/2.0-stable/README.md)_
Requirements:
```
ActiveRecord 4.0.0 - 4.1.x
Ruby 1.9.3+, JRuby
PostGIS 2.0+
```
#### Version 0.6.x supports ActiveRecord 3.x
_If you are using version 0.6.x, you should read [the version 0.6.x / 2.x README](https://github.com/rgeo/activerecord-postgis-adapter/blob/2.0-stable/README.md)_
Requirements:
```
ActiveRecord 3.x only
Ruby 1.8.7+, JRuby, Rubinius
PostGIS 1.5+
```
Gemfile:
```ruby
gem 'activerecord-postgis-adapter', '~> 0.6.6'
```
Please read [PostGIS 1 Notes](https://github.com/rgeo/activerecord-postgis-adapter/blob/master/PostGIS_1.md)
if you would like to use the adapter with an older version of PostGIS.
#### Upgrading to version 8.x
The `PostgisDatabaseTasks` module has been removed which means that the rake tasks to install postgis are no longer available. If using a Rails app, please see [Upgrading an Existing Database](#upgrading-an-existing-database)
#### Upgrading from 6.x
When upgrading from version 6.x to a newer major version, you may need to modify your `SpatialFactoryStore` configuration. Please see this section of the README in rgeo-activerecord for more details (https://github.com/rgeo/rgeo-activerecord#spatial-factories-for-columns).
##### database.yml
You must modify your `config/database.yml` file to use the postgis
adapter. At minimum, you will need to change the `adapter` field from
`postgresql` to `postgis`. Recommended configuration:
```yml
development:
username: your_username
adapter: postgis
host: localhost
schema_search_path: public
```
If you have installed your PostGIS extension in a schema other than `public`, which
is the default, add that schema to your `schema_search_path`:
```yml
development:
schema_search_path: public, postgis
```
Here are some other options that are supported:
```yml
development:
adapter: postgis
encoding: unicode
postgis_extension: postgis # default is postgis
postgis_schema: public # default is public
schema_search_path: public,postgis
pool: 5
database: my_app_development # your database name
username: my_app_user # the username your app will use to connect
password: my_app_password # the user's password
su_username: my_global_user # a superuser for the database
su_password: my_global_pasword # the superuser's password
```
##### `rgeo` dependency
This adapter uses the `rgeo` gem, which has additional dependencies.
Please see the README documentation for `rgeo` for more information: https://github.com/rgeo/rgeo
## Setup
If you have not created your rails app yet start there.
```sh
rails new my_app --database=postgresql
```
Add the gem to your Gemfile.
```ruby
gem 'activerecord-postgis-adapter'
```
And tell ActiveRecord to use the adapter by setting the `adapter` field in `config/database.yml`
```yml
default: &default
adapter: postgis
```
Create the database if you haven't already.
```sh
rake db:create
```
Create a migration to add the PostGIS extension to your database.
```sh
rails generate migration AddPostgisExtensionToDatabase
```
The migration should look something like this:
```ruby
class AddPostgisExtensionToDatabase < ActiveRecord::Migration[7.2]
def change
enable_extension 'postgis'
end
end
```
Then run the migration.
```sh
rails db:migrate
```
### Creating Spatial Tables
To store spatial data, you must create a column with a spatial type. PostGIS
provides a variety of spatial types, including point, linestring, polygon, and
different kinds of collections. These types are defined in a standard produced
by the Open Geospatial Consortium. You can specify options indicating the coordinate
system and number of coordinates for the values you are storing.
The activerecord-postgis-adapter extends ActiveRecord's migration syntax to
support these spatial types. The following example creates five spatial
columns in a table:
```ruby
create_table :my_spatial_table do |t|
t.column :shape1, :geometry
t.geometry :shape2
t.line_string :path, srid: 3785
t.st_point :lonlat, geographic: true
t.st_point :lonlatheight, geographic: true, has_z: true
end
```
The first column, "shape1", is created with type "geometry". This is a general
"base class" for spatial types; the column declares that it can contain values
of _any_ spatial type.
The second column, "shape2", uses a shorthand syntax for the same type as the shape1 column.
You can create a column either by invoking `column` or invoking the name of the type directly.
The third column, "path", has a specific geometric type, `line_string`. It
also specifies an SRID (spatial reference ID) that indicates which coordinate
system it expects the data to be in. The column now has a "constraint" on it;
it will accept only LineString data, and only data whose SRID is 3785.
The fourth column, "lonlat", has the `st_point` type, and accepts only Point
data. Furthermore, it declares the column as "geographic", which means it
accepts longitude/latitude data, and performs calculations such as distances
using a spheroidal domain.
The fifth column, "lonlatheight", is a geographic (longitude/latitude) point
that also includes a third "z" coordinate that can be used to store height
information.
The following are the data types understood by PostGIS and exposed by
activerecord-postgis-adapter:
- `:geometry` -- Any geometric type
- `:st_point` -- Point data
- `:line_string` -- LineString data
- `:st_polygon` -- Polygon data
- `:geometry_collection` -- Any collection type
- `:multi_point` -- A collection of Points
- `:multi_line_string` -- A collection of LineStrings
- `:multi_polygon` -- A collection of Polygons
Following are the options understood by the adapter:
- `:geographic` -- If set to true, create a PostGIS geography column for
longitude/latitude data over a spheroidal domain; otherwise create a
geometry column in a flat coordinate system. Default is false. Also
implies :srid set to 4326.
- `:srid` -- Set a SRID constraint for the column. Default is 4326 for a
geography column, or -1 for a geometry column. Note that PostGIS currently
(as of version 2.0) requires geography columns to have SRID 4326, so this
constraint is of limited use for geography columns.
- `:has_z` -- Specify that objects in this column include a Z coordinate.
Default is false.
- `:has_m` -- Specify that objects in this column include an M coordinate.
Default is false.
To create a PostGIS spatial index, add `using: :gist` to your index:
```ruby
add_index :my_table, :lonlat, using: :gist
# or
change_table :my_table do |t|
t.index :lonlat, using: :gist
end
```
### Attributes
Models may also define attributes using the above data types and options.
```ruby
class SpatialModel < ActiveRecord::Base
attribute :centroid, :st_point, srid: 4326, geographic: true
end
```
`centroid` will not have an associated column in the `spatial_models` table, but any geometry object assigned to the `centroid` attribute will be cast to a geographic point.
### Configuring ActiveRecord
ActiveRecord's usefulness stems from the way it automatically configures
classes based on the database structure and schema. If a column in the
database has an integer type, ActiveRecord automatically casts the data to a
Ruby Integer. In the same way, the activerecord-postgis-adapter automatically
casts spatial data to a corresponding RGeo data type.
RGeo offers more flexibility in its type system than can be
interpreted solely from analyzing the database column. For example, you can
configure RGeo objects to exhibit certain behaviors related to their
serialization, validation, coordinate system, or computation. These settings
are embodied in the RGeo factory associated with the object.
You can configure the adapter to use a particular factory (i.e. a
particular combination of settings) for data associated with each type in
the database.
Here's an example using a Geos default factory:
```ruby
RGeo::ActiveRecord::SpatialFactoryStore.instance.tap do |config|
# By default, use the GEOS implementation for spatial columns.
config.default = RGeo::Geos.factory_generator
# But use a geographic implementation for point columns.
config.register(RGeo::Geographic.spherical_factory(srid: 4326), geo_type: "point")
end
```
The default spatial factory for geographic columns is `RGeo::Geographic.spherical_factory`.
The default spatial factory for cartesian columns is `RGeo::Cartesian.preferred_factory`.
You do not need to configure the `SpatialFactoryStore` if these defaults are ok.
For more explanation of `SpatialFactoryStore`, see [the rgeo-activerecord README](https://github.com/rgeo/rgeo-activerecord#spatial-factories-for-columns)
### Deploying to Heroku
See the [wiki entry](https://github.com/rgeo/activerecord-postgis-adapter/wiki/Heroku) and [linked issue](https://github.com/rgeo/activerecord-postgis-adapter/issues/14) for some notes on Heroku deployments.
Note: RGeo is looking for a Heroku user to help formalize/expand the wiki. If you're interested, please open a PR with a new md file, which can be copied to the wiki.
## Working With Spatial Data
Of course, you're using this adapter because you want to work with geospatial
data in your ActiveRecord models. Once you've installed the adapter, set up
your database, and run your migrations, you can interact directly with spatial
data in your models as RGeo objects.
RGeo is a Ruby implementation of the industry standard OGC Simple Features
specification. It's a set of data types that can represent a variety of
geospatial objects such as points, lines, polygons, and collections. It also
provides the standard set of spatial analysis operations such as computing
intersections or bounding boxes, calculating length or area, and so forth. We
recommend browsing the RGeo documentation for a clearer understanding of its
capabilities. For now, just note that the data values you will be working with
are all RGeo geometry objects.
### Reading and Writing Spatial Columns
When you access a spatial attribute on your ActiveRecord model, it is given to
you as an RGeo geometry object (or nil, for attributes that allow null
values). You can then call the RGeo api on the object. For example, consider
the MySpatialTable class we worked with above:
```ruby
record = MySpatialTable.find(1)
p = record.lonlat # Returns an RGeo::Feature::Point
puts p.x # displays the x coordinate
puts p.geometry_type.type_name # displays "Point"
```
The RGeo factory for the value is determined by how you configured the
ActiveRecord class, as described above. In this case, we explicitly set a
spherical factory for the `:lonlat` column:
```ruby
factory = p.factory # returns a spherical factory
```
You can set a spatial attribute by providing an RGeo geometry object, or by
providing the WKT string representation of the geometry. If a string is
provided, the activerecord-postgis-adapter will attempt to parse it as WKT and
set the value accordingly.
```ruby
record.lonlat = 'POINT(-122 47)' # sets the value to the given point
```
If the WKT parsing fails, the value currently will be silently set to nil. In
the future, however, this will raise an exception.
```ruby
record.lonlat = 'POINT(x)' # sets the value to nil
```
If you set the value to an RGeo object, the factory needs to match the factory
for the attribute. If the factories do not match, activerecord-postgis-adapter
will attempt to cast the value to the correct factory.
```ruby
p2 = factory.point(-122, 47) # p2 is a point in a spherical factory
record.lonlat = p2 # sets the value to the given point
record.shape1 = p2 # shape1 uses a flat geos factory, so it
# will cast p2 into that coordinate system
# before setting the value
record.save
```
If, however, you attempt to set the value to the wrong type-- for example,
setting a linestring attribute to a point value, you will get an exception
from Postgres when you attempt to save the record.
```ruby
record.path = p2 # This will appear to work, but...
record.save # This will raise an exception from the database
```
### Spatial Queries
You can create simple queries based on representational equality in the same
way you would on a scalar column:
```ruby
record2 = MySpatialTable.where(:lonlat => factory.point(-122, 47)).first
```
You can also use WKT:
```ruby
record3 = MySpatialTable.where(:lonlat => 'POINT(-122 47)').first
```
Note that these queries use representational equality, meaning they return
records where the lonlat value matches the given value exactly. A 0.00001
degree difference would not match, nor would a different representation of the
same geometry (like a multipoint with a single element). Equality queries
aren't generally all that useful in real world applications. Typically, if you
want to perform a spatial query, you'll look for, say, all the points within a
given area. For those queries, you'll need to use the standard spatial SQL
functions provided by PostGIS.
To perform more advanced spatial queries, you can use the extended Arel interface included in the activerecord-postgis-adapter. The functions accept WKT strings or RGeo features.
```rb
point = RGeo::Geos.factory(srid: 0).point(1,1)
buildings = Building.arel_table
containing_buiildings = Building.where(buildings[:geom].st_contains(point))
```
See [rgeo-activerecord](https://github.com/rgeo/rgeo-activerecord) for more information about advanced spatial queries.
### Joining Spatial Columns
If a spatial column is joined with another model, `srid` and `geographic` will not be automatically inferred and they will default to 0 and `false`, by default. In order to properly infer these options after a join, an `attribute` must be created on the target table.
```ruby
class SpatialModel < ActiveRecord::Base
belongs_to :foo
# has column geo_point (:st_point, srid: 4326, geographic: true)
end
class Foo < ActiveRecord::Base
has_one :spatial_model
# re-define geo_point here so join works
attribute :geo_point, :st_point, srid: 4326, geographic: true
end
# perform a query where geo_point is joined to foo
foo = Foo.joins(:spatial_models).select("foos.id, spatial_models.geo_point").first
p foo.geo_point.class
# => RGeo::Geographic::SphericalPointImpl
p foo.geo_point.srid
# => 4326
```
## Background: PostGIS
A spatial database is one that includes a set of data types, functions,
tables, and other objects related to geospatial data. When these objects are
present in your database, you can use them to store and query spatial objects
such as points, lines, and polygons.
PostGIS is an extension for PostgreSQL that provides definitions for the objects
you need to add to a database to enable geospatial capabilities.
When you create your Rails database as described above in the section on
installation and configuration, activerecord-postgis-adapter automatically
invokes PostGIS to add the appropriate definitions to your database. You can
determine whether your database includes the correct definitions by attempting
to invoke the POSTGIS_VERSION function:
```sql
SELECT POSTGIS_VERSION(); # succeeds if PostGIS objects are present.
```
Standard spatial databases also include a table called `spatial_ref_sys`. This
table includes a set of "spatial reference systems", or coordinate systems---
for example, WGS84 latitude and longitude, or Mercator Projection. Spatial
databases also usually include a table called `geometry_columns`, which
includes information on each database column that includes geometric data. In
recent versions of PostGIS, `geometry_columns` is actually not a table but a
view into the system catalogs.
## Development and Support
RubyDoc Documentation is available at https://rubydoc.info/gems/activerecord-postgis-adapter
Contributions are welcome. See CONTRIBUTING.md for instructions.
Report issues at https://github.com/rgeo/activerecord-postgis-adapter/issues
Support is also available on the rgeo-users google group at https://groups.google.com/group/rgeo-users
## Acknowledgments
[Daniel Azuma](https://daniel-azuma.com) authored the PostGIS Adapter and its supporting
libraries (including RGeo).
[Tee Parham](https://twitter.com/teeparham) is a former maintainer.
[Keith Doggett](https://github.com/keithdoggett) is a current maintainer.
[Ulysse Buonomo](https://github.com/BuonOmo) is a current maintainer.
Development is supported by:
- [Klaxit](https://www.klaxit.com)
- Goldfish Ads
This adapter implementation owes some debt to the spatial_adapter plugin
(https://github.com/fragility/spatial_adapter). Although we made some different
design decisions for this adapter, studying the spatial_adapter source gave us
a head start on the implementation.
## License
Copyright Daniel Azuma, Tee Parham
https://github.com/rgeo/activerecord-postgis-adapter/blob/master/LICENSE.txt