postgis

README

PostGIS

The PostGIS provider manages querying for tile requests against a Postgres database with the PostGIS extension installed. The connection between tegola and Postgis is configured in a tegola.toml file. An example minimum connection config:

[[providers]]
name = "test_postgis"       # provider name is referenced from map layers (required)
type = "postgis"            # the type of data provider must be "postgis" for this data provider (required)
host = "localhost"          # PostGIS database host (required)
port = 5432                 # PostGIS database port (required)
database = "tegola"         # PostGIS database name (required)
user = "tegola"             # PostGIS database user (required)
password = ""               # PostGIS database password (required)

Connection Properties

• name (string): [Required] provider name is referenced from map layers
• type (string): [Required] the type of data provider. must be "postgis" to use this data provider
• host (string): [Required] PostGIS database host
• port (int): [Required] PostGIS database port (required)
• database (string): [Required] PostGIS database name
• user (string): [Required] PostGIS database user
• password (string): [Required] PostGIS database password
• srid (int): [Optional] The default SRID for the provider. Defaults to WebMercator (3857) but also supports WGS84 (4326)
• max_connections (int): [Optional] The max connections to maintain in the connection pool. Defaults to 100. 0 means no max.

Provider Layers

In addition to the connection configuration above, Provider Layers need to be configured. A Provider Layer tells tegola how to query PostGIS for a certain layer. An example minimum config:

[[providers.layers]]
name = "landuse"
# this table uses "geom" for the geometry_fieldname and "gid" for the id_fieldname so they don't need to be configured
tablename = "gis.zoning_base_3857"  

Provider Layers Properties

• name (string): [Required] the name of the layer. This is used to reference this layer from map layers.
• tablename (string): [*Required] the name of the database table to query against. Required if sql is not defined.
• geometry_fieldname (string): [Optional] the name of the filed which contains the geometry for the feature. defaults to geom
• id_fieldname (string): [Optional] the name of the feature id field. defaults to gid
• fields ([]string): [Optional] a list of fields to include alongside the feature. Can be used if sql is not defined.
• srid (int): [Optional] the SRID of the layer. Supports 3857 (WebMercator) or 4326 (WGS84).
• sql (string): [*Required] custom SQL to use use. Required if tablename is not defined. Supports the following tokens:
  • !BBOX! - [Required] will be replaced with the bounding box of the tile before the query is sent to the database.
  • !ZOOM! - [Optional] will be replaced with the "Z" (zoom) value of the requested tile.

*Required: either the tablename or sql must be defined, but not both.

Example minimum custom SQL config

[[providers.layers]]
name = "rivers"
# custom SQL to be used for this layer. Note: that the geometery field is wrapped
# in ST_AsBinary() and a !BBOX! token is supplied for querying the table with the tile bounds
sql = "SELECT gid, ST_AsBinary(geom) AS geom FROM gis.rivers WHERE geom && !BBOX!"

Testing

Testing is designed to work against a live PostGIS database. To run the PostGIS tests, the following environment variables need to be set:

$ export RUN_POSTGIS_TESTS=yes
$ export PGHOST="localhost"
$ export PGPORT=5432
$ export PGDATABASE="tegola"
$ export PGUSER="postgres"
$ export PGPASSWORD=""

Documentation

Index

• Constants
• func NewTileProvider(config map[string]interface{}) (provider.Tiler, error)
• type ErrLayerNotFound
  • func (e ErrLayerNotFound) Error() string
• type Layer
  • func (l Layer) GeomFieldName() string
  • func (l Layer) GeomType() geom.Geometry
  • func (l Layer) IDFieldName() string
  • func (l Layer) Name() string
  • func (l Layer) SRID() uint64
• type Provider
  • func (p *Provider) Layer(name string) (Layer, bool)
  • func (p Provider) Layers() ([]provider.LayerInfo, error)
  • func (p Provider) TileFeatures(ctx context.Context, layer string, tile provider.Tile, ...) error

Constants

const (
	DefaultPort    = 5432
	DefaultSRID    = tegola.WebMercator
	DefaultMaxConn = 100
)

const (
	ConfigKeyHost        = "host"
	ConfigKeyPort        = "port"
	ConfigKeyDB          = "database"
	ConfigKeyUser        = "user"
	ConfigKeyPassword    = "password"
	ConfigKeyMaxConn     = "max_connections"
	ConfigKeySRID        = "srid"
	ConfigKeyLayers      = "layers"
	ConfigKeyLayerName   = "name"
	ConfigKeyTablename   = "tablename"
	ConfigKeySQL         = "sql"
	ConfigKeyFields      = "fields"
	ConfigKeyGeomField   = "geometry_fieldname"
	ConfigKeyGeomIDField = "id_fieldname"
)

const Name = "postgis"

Functions

func NewTileProvider

func NewTileProvider(config map[string]interface{}) (provider.Tiler, error)

NewTileProvider instantiates and returns a new postgis provider or an error. The function will validate that the config object looks good before trying to create a driver. This Provider supports the following fields in the provided map[string]interface{} map:

host (string): [Required] postgis database host
port (int): [Required] postgis database port (required)
database (string): [Required] postgis database name
user (string): [Required] postgis database user
password (string): [Required] postgis database password
srid (int): [Optional] The default SRID for the provider. Defaults to WebMercator (3857) but also supports WGS84 (4326)
max_connections : [Optional] The max connections to maintain in the connection pool. Default is 100. 0 means no max.
layers (map[string]struct{})  — This is map of layers keyed by the layer name. supports the following properties

	name (string): [Required] the name of the layer. This is used to reference this layer from map layers.
	tablename (string): [*Required] the name of the database table to query against. Required if sql is not defined.
	geometry_fieldname (string): [Optional] the name of the filed which contains the geometry for the feature. defaults to geom
	id_fieldname (string): [Optional] the name of the feature id field. defaults to gid
	fields ([]string): [Optional] a list of fields to include alongside the feature. Can be used if sql is not defined.
	srid (int): [Optional] the SRID of the layer. Supports 3857 (WebMercator) or 4326 (WGS84).
	sql (string): [*Required] custom SQL to use use. Required if tablename is not defined. Supports the following tokens:

		!BBOX! - [Required] will be replaced with the bounding box of the tile before the query is sent to the database.
		!ZOOM! - [Optional] will be replaced with the "Z" (zoom) value of the requested tile.

Types

type ErrLayerNotFound

type ErrLayerNotFound struct {
	LayerName string
}

func (ErrLayerNotFound) Error

func (e ErrLayerNotFound) Error() string

type Layer

type Layer struct {
	// contains filtered or unexported fields
}

layer holds information about a query.

func (Layer) GeomFieldName

func (l Layer) GeomFieldName() string

func (Layer) GeomType

func (l Layer) GeomType() geom.Geometry

func (Layer) IDFieldName

func (l Layer) IDFieldName() string

func (Layer) Name

func (l Layer) Name() string

func (Layer) SRID

func (l Layer) SRID() uint64

type Provider

type Provider struct {
	// contains filtered or unexported fields
}

Provider provides the postgis data provider.

func (*Provider) Layer

func (p *Provider) Layer(name string) (Layer, bool)

Layer fetches an individual layer from the provider, if it's configured if no name is provider, the first layer is returned

func (Provider) Layers

func (p Provider) Layers() ([]provider.LayerInfo, error)

Layers returns meta data about the various layers which are configured with the provider

func (Provider) TileFeatures

func (p Provider) TileFeatures(ctx context.Context, layer string, tile provider.Tile, fn func(f *provider.Feature) error) error

TileFeatures adheres to the provider.Tiler interface