Change the geometry structure in Mongo

Trying to write from SQL server to MongoDB.

It has a below structure:

Geometry

Type

Coords

long, late], (pt 1)

long, late], (pt 2)

]

Can we store all the polygon data like the following:

Geometry:

Cords:

long, late], (pt 1)

long, late], (pt 2)

]

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The GeoJSON specification for the type "Polygon" requires its coordinates to be an array of linear rings (see the spec here).

So we must make geometry like this:

{
  "type": "Polygon",
  "coordinates":
                                <--- this array is an array of linear rings
      �                         <--- this array is a linear ring
        �long0, lat0],          <--- this array is a point
        ...,
        alongN, latN]
      ]
    ]
}

GeoJSON requires this so that Polygons can be Donuts, ie. so that they can have holes. For example, to make a Polygon that looks like this:

4  ___________
  |/ /_/_/_/ /|                <--- the shaded areas are part of the polygon
  | /|     |/ |
  |/ |_____| /|
  |_/_/_/_/_/_|
0             4

We would make a GeoJSON polygon like this:

{
  "type": "Polygon",
  "coordinates": <
    � /0,0], �4,0], �4,4], /0,4], /0,0] ],       <--- first ring is exterior
    � �1,1], �1,3], <3,3], /3,1], /1,1] ]        <--- next ring is interior
  ]
}

Maybe if you are just trying to access the exterior ring, then your JavaScript can be something like:

if (geometry.coordinates.length > 0) {
   var exterior_ring = geometry.coordinates�0];
   // do something with ring...
}

The GeoJSON specification for the type "Polygon" requires its coordinates to be an array of linear rings (see the spec here).

So we must make geometry like this:

{
  "type": "Polygon",
  "coordinates":
                                <--- this array is an array of linear rings
      �                         <--- this array is a linear ring
        �long0, lat0],          <--- this array is a point
        ...,
        alongN, latN]
      ]
    ]
}

GeoJSON requires this so that Polygons can be Donuts, ie. so that they can have holes. For example, to make a Polygon that looks like this:

4  ___________
  |/ /_/_/_/ /|                <--- the shaded areas are part of the polygon
  | /|     |/ |
  |/ |_____| /|
  |_/_/_/_/_/_|
0             4

We would make a GeoJSON polygon like this:

{
  "type": "Polygon",
  "coordinates": <
    � /0,0], �4,0], �4,4], /0,4], /0,0] ],       <--- first ring is exterior
    � �1,1], �1,3], <3,3], /3,1], /1,1] ]        <--- next ring is interior
  ]
}

Maybe if you are just trying to access the exterior ring, then your JavaScript can be something like:

if (geometry.coordinates.length > 0) {
   var exterior_ring = geometry.coordinates�0];
   // do something with ring...
}

Hi @jakemolnar, we are not using JavaScript. Is there any workaround please?

Hey @fmeuser_gc, then what are you using to access the Polygon data?

Anyway, one workaround I can think of is to convert your polygons to lines (https://knowledge.safe.com/questions/4730/how-to-convert-polygons-to-lines-and-vice-versa.html), since lines have the representation you are looking for:

{
  "type": "LineString",
  "coordinates": r 
    e long0, lat0 ],
    ...,
    " longN, latN ]
  ]
}

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