Coverage for gws-app/gws/base/exporter/__init__.py: 100%

1"""Feature export. 

2 

3Exports features selected in the client to files, such as Shapefile, GeoJSON, 

4GML, KML or CSV. Exports run as background jobs. Concrete exporters, one per 

5format, live in ``gws.plugin.exporter``. 

6 

7Submodules 

8---------- 

9 

10- ``core`` - the base exporter object with its configuration and props. 

11 Subclasses declare which kinds of data they support and implement ``run``. 

12 ``withMultiLayer`` is only enabled if the subclass supports multiple layers. 

13- ``manager`` - the exporter manager (``root.app.exporterMgr``). It lists the 

14 exporters available to a user, starts export jobs and runs exports directly 

15 from the command line. 

16- ``worker`` - the job worker. It loads the requested features, finds the 

17 exporter and calls its ``run`` method, reporting progress to the job. 

18- ``action`` - the ``exporter`` action with the API commands to start, poll, 

19 cancel and download an export, and the ``gws exporter export`` command line 

20 command. 

21- ``util`` - helpers for exporters: grouping features by model with consistent 

22 columns, geometry type and CRS, and a complete export with a GDAL vector driver. 

23 

24Exporters are configured on projects and on the application (``exporters``). 

25For a project, the exporters of the project and of the application that the 

26user can use are offered; of several exporters with the same title, only the 

27first one is used. 

28 

29Export flow 

30----------- 

31 

321. The client sends ``exporterStart`` with a ``gws.ExportRequest`` (exporter 

33 uid and feature props). The manager creates a job for the worker and 

34 schedules it. The request is passed to the worker through a pickled file 

35 in the ephemeral directory. 

362. The worker loads the features. Depending on the ``exportStrategy`` of 

37 their model, features are read from the model by uid or built from the 

38 props sent by the client. 

393. The exporter writes the files and fills the ``gws.ExportResult``: the path 

40 of the result file, its mime type and counts. The GDAL helper in ``util`` 

41 zips the files if there is more than one. 

424. The client polls ``exporterStatus``. When the job is complete, the status 

43 contains the counts and a URL for ``exporterOutput``, which returns the file. 

44 

45In the ``util`` helpers, a feature that does not fit its group (no geometry, a different geometry type 

46or a different CRS) is skipped with an error in the result, unless the 

47exporter allows it with ``withNoGeometry``, ``withMixedGeometry`` or 

48``withMixedCrs``. 

49 

50Example:: 

51 

52 actions+ { 

53 type "exporter" 

54 } 

55 

56 exporters+ { 

57 type "geojson" 

58 title "GeoJSON" 

59 target "download" 

60 access "allow all" 

61 } 

62 

63 exporters+ { 

64 type "gml" 

65 title "GML (one file)" 

66 target "download" 

67 withMultiLayer true 

68 access "allow all" 

69 } 

70 

71From the command line, with a request stored as JSON:: 

72 

73 gws exporter export --request request.json --output export.zip 

74 

75Implementing an exporter:: 

76 

77 @gws.ext.object.exporter('myformat') 

78 class Object(gws.base.exporter.Object): 

79 supportsVector = True 

80 supportsRaster = False 

81 supportsMultiLayer = False 

82 

83 def run(self, ea, er): 

84 gws.base.exporter.util.run_gdal_vector_export('MyDriver', 'application/x-my', ea, er) 

85""" 

86 

87from .core import Config, Object, Props 

88from . import manager, util 

89