gnome.persist.save_load¶

Save/load gnome objects

Attributes¶

log

Classes¶

`Refs`	Class to store and handle references during saving/loading.
`References`	PyGnome objects like the PointWindMover contain other objects, eg Wind object.
`Savable`	Create a mixin for save/load options for saving and loading serialized

Functions¶

`load`(saveloc[, fname, references])	read json from file and load the appropriate object
`is_savezip_valid`(savezip)	some basic checks on validity of zipfile. Primarily for checking save
`zipfile_folders`(zip_file)	Get a list of the folders in our archive.
`extract_zipfile`(zip_file[, to_folder, prefix])

Module Contents¶

gnome.persist.save_load.log¶

class gnome.persist.save_load.Refs¶

Bases: dict

Class to store and handle references during saving/loading. Provides some convenience functions

Initialize self. See help(type(self)) for accurate signature.

gen_default_name(obj)¶: Goes through the dict, finds all objects of obj.obj_type stored, and provides a unique name by appending length+1

class gnome.persist.save_load.References¶

Bases: object

PyGnome objects like the PointWindMover contain other objects, eg Wind object. When persisting a Model, the Wind object is not created by the PointWindMover, it is merely referenced by the PointWindMover. When persisting a Model, the referenced objects are saved in their own file and a reference is stored for it. This class manages these references.

property files¶

get_reference(obj)¶: return key if obj already exists in references list else return None

reference(obj, name=None)¶

Get a unique reference to the object. By default this string is the filename in which the json for the object is stored If a reference to obj already exists, then it is returned

Parameters:

obj – object for which a reference must be added
name=None – add an object reference specified by ‘name’ for filename

retrieve(ref)¶: retrieve the object associated with the reference

gnome.persist.save_load.load(saveloc, fname='Model.json', references=None)¶

read json from file and load the appropriate object This is a general purpose load method that looks at the json[‘obj_type’] and invokes json[‘obj_type’].loads(json) method

Parameters:

saveloc – path to zipfile that contains data files and json files. It could also be a directory containing files - keep original support for location files.
fname – .json file to load. Default is ‘Model.json’. zipfile/dir must contain ‘fname’
references=None – References object that keeps track of objects in a dict as they are constructed, using the filename as the key

Returns:

object constructed from the json

Note

Function first assumes saveloc is a directory and looks for saveloc/fname. If this fails, it checks if saveloc is a zipfile. If this fails, it checks if saveloc is a file and loads this assuming its json for a gnome object. If none of these work, it just returns None.

class gnome.persist.save_load.Savable¶

Bases: object

Create a mixin for save/load options for saving and loading serialized gnome objects. Mix this in with the Serializable class so all gnome objects can save/load themselves

classmethod loads(json_data, saveloc=None, references=None)¶

loads object from json_data

load json for references from files
update paths of datafiles if needed
deserialize json_data
and create object with new_from_dict()

json_data: dict containing json data. It has been parsed through the: json.loads() command. The json will be valided here when it gets deserialized. Its references and datafile paths will be recreated here prior to calling new_from_dict()

Optional parameter

Parameters:

saveloc – location of data files or .json files for objects stored as references. If object requires no datafiles and does not need to read references from a .json file in saveloc, then this can be None.
references – references object - if this is called by the Model, it will pass a references object. It is not required.

Returns:

object constructed from json_data.

gnome.persist.save_load.is_savezip_valid(savezip)¶

some basic checks on validity of zipfile. Primarily for checking save zipfiles loaded from the Web. Following are the types of errors it checks:

Returns:: True if zip is valid, False otherwise

Failed to open zipfile
CRC failed for a file in the archive - rejecting zip
Found a *.json with size > _max_json_filesize - rejecting
Reject - found a file with:
uncompressed_size/compressed_size > _max_compress_ratio.
Found a file in archive that has path outside of saveloc - rejecting
rejects zipfile if it contains an archive with ‘..’

Note

can change _max_json_filesize, _max_compress_ratio if required.

gnome.persist.save_load.zipfile_folders(zip_file)¶: Get a list of the folders in our archive. - MAC OS X created zipfiles contain a folder named ‘__MACOSX/’,

which is intended to contain file and folder related metadata. we would like to ignore this folder.

gnome.persist.save_load.extract_zipfile(zip_file, to_folder='.', prefix='')¶