flywheel.models module

Model code

class flywheel.models.Model(*args, **kwargs)

Bases: object

Base class for all tube models

For documentation on the metadata fields, check the attributes on the ModelMetadata class.

Attributes:

__metadata_class__ : class

Container for model metadata

__metadata__ : dict

For details see Metadata

meta_ : ModelMetadata

The metadata for the model

__engine__ : Engine

Cached copy of the Engine that was used to save/load the model. This will be set after saving or loading a model.

__dirty__ : set

The set of all immutable fields that have been changed since the last save operation.

__cache__ : dict

The last seen value that was stored in the database. This is used to construct the expects dict when making updates that raise on conflict.

__incrs__ : dict

Mapping of fields to atomic add/delete operations for numbers and sets.

add_(**kwargs)

Atomically add to a set

cached_(name, default=None)

Get the cached (server) value of a field

construct_ddb_expects_(fields=None)

Construct a dynamo “expects” mapping based on the cached fields

ddb_dump_()

Return a dict for inserting into DynamoDB

ddb_dump_cached_(name)

Dump a cached field to a Dynamo-friendly value

ddb_dump_field_(name)

Dump a field to a Dynamo-friendly value

classmethod ddb_load_(engine, data)

Load a model from DynamoDB data

delete(*args, **kwargs)

Delete the model from the database

classmethod field_(name)

Get Field or construct a placeholder for an undeclared field

This is used for creating scan filter constraints on fields that were not declared in the model

hk_

The value of the hash key

incr_(**kwargs)

Atomically increment a number value

index_pk_dict_(index_name)

The primary key dict for an index, encoded for dynamo

keys_()

All declared fields

loading_(**kwds)

Context manager to speed up object load process

mark_dirty_(name)

Mark that a field is dirty

meta_ = <flywheel.model_meta.ModelMetadata object>

mutate_(action, **kwargs)

Atomically mutate a set

partial_loading_(**kwds)

For use when loading a partial object (i.e. from update_field)

persisted_

True if the model exists in DynamoDB, False otherwise

pk_dict_

The primary key dict, encoded for dynamo

pk_tuple_

The primary key dict, encoded for dynamo

post_load_(engine)

Called after model loaded from database

post_save_()

Called after item is saved to database

post_save_fields_(fields)

Called after update_field or update_fields

pre_save_(engine)

Called before saving items

refresh(consistent=False)

Overwrite model data with freshest from database

remove_(**kwargs)

Atomically remove from a set

rk_

The value of the range key

save(overwrite=None)

Save model data to database (see also: sync)

set_ddb_val_(key, val)

Decode and set a value retrieved from Dynamo

sync(*args, **kwargs)

Sync model changes back to database

class flywheel.models.SetDelta

Bases: object

Wrapper for an atomic change to a Dynamo set

Used to track the changes when using add_() and remove_()

add(action, value)

Add another update to the delta

Parameters:

action : {‘ADD’, ‘DELETE’}

value : object

The value to add or remove

merge(other)

Merge the delta with a set

Parameters:

other : set

The original set to merge the changes with