Inserting and Selecting PostGIS Geometry with Gorm
Inserting and retrieving geometric data types in Golang can be challenging, especially when using libraries like Gorm. However, by leveraging the ST_AsBinary() and ST_GeomFromWKB() functions in PostGIS, we can efficiently interact with geometry columns.
Inserting with orb.Point
To insert orb.Point data into a geometry column, we wrap the point in the ST_GeomFromWKB() function using the Value() method of EWKBGeomPoint. The Value() method in our custom struct EWKBGeomPoint performs the conversion before returning the value to Gorm for insertion.
Querying with binary data
When querying, Gorm automatically calls the Scan() method of our custom struct EWKBGeomPoint. In this method, we receive the binary data from the database and convert it to an orb.Point using the Unmarshal function from the ewkb library.
Trigger or Rule Automation
To handle the automatic transformation of data into and out of the geometry column, we can customize the database migration process. We first create the table with the geometry column using standard SQL syntax. After creating the table, we use gormigrate to create the Gorm model and other columns.
This approach ensures that all orb.Points inserted into the database are properly converted to WKB format, and all binary data retrieved from the database is correctly converted to orb.Point format.
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