flytekit.extend.Promise#

class flytekit.extend.Promise(var, val, type=None)[source]#

This object is a wrapper and exists for three main reasons. Let’s assume we’re dealing with a task like

@task
def t1() -> (int, str): ...

Handling the duality between compilation and local execution - when the task function is run in a local execution mode inside a workflow function, a Python integer and string are produced. When the task is being compiled as part of the workflow, the task call creates a Node instead, and the task returns two Promise objects that point to that Node.
One needs to be able to call
```
x = t1().with_overrides(...)
```
If the task returns an integer or a (int, str) tuple like t1 above, calling with_overrides on the result would throw an error. This Promise object adds that.
Assorted handling for conditionals.

Methods

Parameters:

var (str)
val (Union[NodeOutput, _literals_models.Literal])
type (Optional[_type_models.LiteralType])

deepcopy()[source]#

Return type:: Promise

eval()[source]#

Return type:: Any

is_(v)[source]#

Parameters:: v (bool)
Return type:: ComparisonExpression

is_false()[source]#

Return type:: ComparisonExpression

is_none()[source]#

Return type:: ComparisonExpression

is_true()[source]#

Return type:: ComparisonExpression

with_overrides(node_name=None, aliases=None, requests=None, limits=None, timeout=<object object>, retries=None, interruptible=None, name=None, task_config=None, container_image=None, accelerator=None, cache=None, cache_version=None, cache_serialize=None, *args, **kwargs)[source]#

Parameters:

node_name (str | None)
aliases (Dict[str, str] | None)
requests (Resources | None)
limits (Resources | None)
timeout (int | timedelta | object | None)
retries (int | None)
interruptible (bool | None)
name (str | None)
task_config (Any | None)
container_image (str | None)
accelerator (BaseAccelerator | None)
cache (bool | None)
cache_version (str | None)
cache_serialize (bool | None)

with_var(new_var)[source]#

Parameters:: new_var (str)
Return type:: Promise

Attributes

attr_path: The attribute path the promise will be resolved with. :rtype: List[Union[str, int]]

is_ready

Returns if the Promise is READY (is not a reference and the val is actually ready)

Usage

p = Promise(...)
...
if p.is_ready():
     print(p.val)
else:
     print(p.ref)

ref: If the promise is NOT READY / Incomplete, then it maps to the origin node that owns the promise

val: If the promise is ready then this holds the actual evaluate value in Flyte’s type system

var: Name of the variable bound with this promise