polygon field added

[soheildsh]

I tried to add polygon field from geodjango. thanks for you consideration.

[codecov-io]

Codecov Report

Merging #155 (60929b6) into master (480b6b9) will decrease coverage by 1.16%.
The diff coverage is 80.26%.

@@            Coverage Diff             @@
##           master     #155      +/-   ##
==========================================
- Coverage   93.67%   92.51%   -1.17%     
==========================================
  Files           9        9              
  Lines         759      855      +96     
==========================================
+ Hits          711      791      +80     
- Misses         48       64      +16     

Impacted Files	Coverage Δ
drf_extra_fields/geo_fields.py	86.95% <78.57%> (-5.73%)	⬇️
tests/test_fields.py	95.02% <81.25%> (-1.81%)	⬇️
drf_extra_fields/fields.py	90.05% <0.00%> (+0.17%)	⬆️

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[alicertel]

This doesn't support polygon with inner rings.

How about we use the following format with the key coordinates?

Polygon with single ring (The way you implemented.)

coordinates : [
     [ [ 2 , 2 ] , [ 3 , 3 ] , [ 4 , 2 ] , [ 2 , 2 ] ]
  ]

Polygon with multiple rings (The one that is not supported at the moment.)

coordinates : [
     [ [ 0 , 0 ] , [ 3 , 6 ] , [ 6 , 1 ] , [ 0 , 0 ] ],
     [ [ 2 , 2 ] , [ 3 , 3 ] , [ 4 , 2 ] , [ 2 , 2 ] ]
  ]

From geojson specification

The "coordinates" member must be an array of LinearRing coordinate arrays. For Polygons with multiple rings, the first must be the exterior ring and any others must be interior rings or holes.

Please see django documentation for usage.

[alicertel]

Hi @yekmolsoheil Thank you for the great addition. I've made a suggestion to make it more compatible with django's Polygon field.

[soheildsh]

Hi. I'm on it. Soon I will also add the things that you said. thanks for your consideration and excellent review and additions.

[soheildsh]

Hey. Polygons with interior rings are added to be supported. also the tests have been passed. Can you now try to review this one more time. If the code is ok we may proceed to add this feature. Thanks