Geography data type

You can formally represent geographical entities with the Geography data type. This implies that at the database level, geographical information is stored using specific data types supported by different database management systems.

There are specialized variants of the Geography data type, named GeoPoint, GeoLine, and GeoPolygon types. They are derived from the Geography data type.

Use cases

Closest Points

Suppose you need to store tourist attractions, so you define the following Transaction object: Place { PlaceId* PlaceName --> Character data type PlaceGeo --> Geography data type } After that, you define a Web Panel object in which, given any point and a distance in meters, it displays all tourist attractions located within that radius from the point. &MyPoint --> Geography data type &Distance --> Numeric data type Event Load For each Place where PlaceGeo.Distance(&MyPoint) < &Distance &PlaceName=PlaceName load endfor EndEvent

Point in a Polygon

Consider the following Transaction object: Neighborhood { NeighborhoodId* NeighborhoodName --> Character data type NeighborhoodPlace --> Geography data type } Suppose you define a Web Panel object in which, given a specific tourist attraction (the end user indicates the point in the map), it shows the neighborhood or zone where that attraction is located: &MyPoint --> Geography data type &NeighborhoodPlace --> Geography data type Event 'Get_Neighborhood' For each Neighborhood Where NeighborhoodPlace.Intersect(&Mypoint) &NeighborhoodId = NeighborhoodId   &NeighborhoodName = NeighborhoodName &NeighborhoodPlace = NeighborhoodPlace endfor Endevent

Data Input

Consider the following Transaction object:

Place
{
  PlaceId* 
  PlaceName --> Character data type
  PlaceGeo --> Geography data type
}

You can run the Transaction and double-click on the map associated with the PlaceGeo attribute present in the Layout. When saving, the Geography data will be stored for the place record.

In addition, you can use the FromWkt and FromGeoJSON methods to load data into an attribute based on the Geography data type.

Although the FromString method could be used, the one to be used is the FromWkt method.

Samples

Consider the following Transaction object:

Place
{
  PlaceId* 
  PlaceName --> Character data type
  PlaceGeo --> Geography data type
}

The PlaceGeo attribute is defined based on the Geography data type to store Points, Lines, or Polygons as needed.

The first three samples below store Points. If the PlaceGeo attribute were of the GeoPoint data type, the same proposed syntax would apply identically. 

The other examples store Line and Polygon data in the PlaceGeo attribute. The same proposed syntax would apply identically if the PlaceGeo attribute were of the GeoLine or GeoPolygon data type, respectively.

New 
   PlaceId = 1 
   PlaceName = "Palacio Legislativo" 
   PlaceGeo = GeoPoint.New(-34.8910275746741, -56.18720064473088)
endNew

New
   PlaceId = 2
   PlaceName = "Golf Club"
   PlaceGeo.FromWkt("POINT(-56.163740158081055 -34.92478600243492)")
endNew

New
   PlaceId = 3
   PlaceName = "Ramirez Beach"
   PlaceGeo.FromGeoJson('{"type":"Point","coordinates":[-56.1701774597168,-34.91676309400329]}')
endnew

New PlaceId = 4   
   PlaceName = "Constituyente, Avenue"
   PlaceGeo.FromGeoJson('{ "type": "LineString", "coordinates": [ [ -56.18528366088867, -34.90571271703311 ], [ -56.17850303649902, -34.90641660705113 ], [ -56.15318298339844, -34.9140182347531 ], [ -56.14863395690918, -34.91521472314688 ] ] }')
endnew

new
  PlaceId = 5
  PlaceName = "Punta Carretas, Neighborhood" 
    &geojsonNeighborhood = '{ "type": "Polygon",  "coordinates": [ [ [-56.148808,-34.918453], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.154835,-34.917061' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.156059,-34.916466' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.156250,-34.914318' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.162754,-34.914791' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.162003,-34.921761' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.165714,-34.919930' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.165737,-34.919930' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.168247,-34.919525' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.169598,-34.918205' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.171421,-34.919209' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.172668,-34.919685' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.172558,-34.920406' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.171207,-34.921566' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.171852,-34.924698' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.171249,-34.925278' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.169662,-34.925438' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.165329,-34.927372' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.161766,-34.929379' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.159920,-34.930645' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.157967,-34.927776' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.156445,-34.927177' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.153141,-34.925507' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.151508,-34.924644' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.151489,-34.923008' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.149151,-34.921497' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.148506,-34.921585' + '], ['
    &geojsonNeighborhood = &geojsonNeighborhood + '-56.148808,-34.918453' + '] ] ] }'
  PlaceGeo.FromGeoJson(&geojsonNeighborhood)
endnew

New
  PlaceId = 6
  PlaceName = "Bulevar Artigas, Boulevard"
  PlaceGeo.FromString("LINESTRING(-56.16090774536133 -34.928797162523516, -56.1650276184082 -34.89494244739731)") 
endnew

new   
   PlaceId = 7
   PlaceName = "Cerro, Neighborhood"
   PlaceGeo.FromString('POLYGON ((-56.248367 -34.873821, -56.266563 -34.876427, -56.263733 -34.890366, -56.268799 -34.893394, -56.26897 -34.900291, -56.264851 -34.902615, -56.253605 -34.895645, -56.247597 -34.895153, -56.246052 -34.889523, -56.248367 -34.873821, -56.248367 -34.873821))') 
endnew

KB Sample

Geography data type Sample

Requirements

- API Key

To view a geographical variable or attribute in the form, only one provider is used: GoogleMaps. For this, you must configure an API Key.

In the case of Android apps, you must configure the Android Maps API Key property.

In the case of Web Panels, you must configure the API Key for each control in the form, as follows:

To obtain an API Key for JavaScript, click here.

For it to work properly, most likely you will need to enable more than one API for this Key. For Example: Maps JavaScript API, Maps static API, Geocoding API, Geolocation API are commonly used.

- Database Management Systems

SQL Server: Version 2008 or higher is required.
In the case of SQL Server 2014 or higher, the SQL Server 2012 Feature pack must be installed on the web server.

MySQL/MariaDB: Version 5.7.5 or higher.
Version 8.0 is not supported yet.

Oracle: Oracle Locator or Oracle Spatial installed. For Oracle 11.g or higher, it’s already installed by default.

PostgreSQL: It’s necessary to install the PostGIS extension from PostgreSQL. At the time of database creation, you must set the value “postgis” in the property “PostgreSQL Extensions” (before executing the reorganization).

Limitations

DBMS: In GeneXus 15, in DB2 and Informix this functionality is not supported.

Compatibility

In previous versions, to represent geographical information some functionalities were used, such as:
- Geolocation domain (Deprecated)
- Map User Control in Web Panels (Available)
- Grid with Control Type = Maps in Panels (Available)
- Geolocation external object (Available)

Geography Properties

Geography Methods

There is also a static version of these methods.

Scope

DBMSs: SQL Server, Oracle, MySQL, SAP Hana, PostgreSQL
Generators: .NET, .NET Framework, Java, Android, Apple