pystac.layout#

class pystac.layout.AsIsLayoutStrategy[source]#

Layout strategy that simply preserves the current href of all objects.

If any object doesn’t have a self href, a ValueError is raised.

get_catalog_href(cat: Catalog, parent_dir: str, is_root: bool) str[source]#
get_collection_href(col: Collection, parent_dir: str, is_root: bool) str[source]#
get_item_href(item: Item, parent_dir: str) str[source]#
class pystac.layout.BestPracticesLayoutStrategy[source]#

Layout strategy that represents the catalog layout described in the STAC Best Practices documentation

For a root catalog or collection, this will use the filename ‘catalog.json’ or ‘collection.json’ to the given directory. For a non-root catalog or collection, the ID will be used as a subdirectory, e.g. ${id}/catalog.json or ${id}/collection.json. For items, a subdirectory with a name of the item ID will be made, and the item ID will be used in the filename, i.e. ${id}/${id}.json

All paths are appended to the parent directory.

get_catalog_href(cat: Catalog, parent_dir: str, is_root: bool) str[source]#
get_collection_href(col: Collection, parent_dir: str, is_root: bool) str[source]#
get_item_href(item: Item, parent_dir: str) str[source]#
class pystac.layout.CustomLayoutStrategy(catalog_func: Callable[[Catalog, str, bool], str] | None = None, collection_func: Callable[[Collection, str, bool], str] | None = None, item_func: Callable[[Item, str], str] | None = None, fallback_strategy: HrefLayoutStrategy | None = None)[source]#

Layout strategy that allows users to supply functions to dictate stac object paths.

Parameters:
  • catalog_func – A function that takes an catalog, a parent directory, and a flag specifying whether or not this catalog is the root. If it is the root, its usually best to not create a subdirectory and put the Catalog file directly in the parent directory. Must return the string path.

  • collection_func – A function that is used for collections in the same manner at catalog_func. This takes the same parameters.

  • item_func – A function that takes an item and a parent directory and returns the path to be used for the item.

  • fallback_strategy – The fallback strategy to use if a function is not provided for a stac object type. Defaults to BestPracticesLayoutStrategy

catalog_func: Callable[[Catalog, str, bool], str] | None#

A function that takes a Catalog, a parent directory, and a boolean specifying whether or not this Catalog is the root. If it is the root, it is usually best to not create a subdirectory and put the Catalog file directly in the parent directory. Must return the string path.

collection_func: Callable[[Collection, str, bool], str] | None#

A function that is used for collections in the same manner as catalog_func. This takes the same parameters.

fallback_strategy: HrefLayoutStrategy#

The fallback strategy to use if a function is not provided for a stac object type. Defaults to BestPracticesLayoutStrategy.

get_catalog_href(cat: Catalog, parent_dir: str, is_root: bool) str[source]#
get_collection_href(col: Collection, parent_dir: str, is_root: bool) str[source]#
get_item_href(item: Item, parent_dir: str) str[source]#
item_func: Callable[[Item, str], str] | None#

An optional function that takes an Item and a parent directory and returns the path to be used for the Item.

class pystac.layout.HrefLayoutStrategy[source]#

Base class for HREF Layout strategies.

abstract get_catalog_href(cat: Catalog, parent_dir: str, is_root: bool) str[source]#
abstract get_collection_href(col: Collection, parent_dir: str, is_root: bool) str[source]#
get_href(stac_object: STACObject, parent_dir: str, is_root: bool = False) str[source]#
abstract get_item_href(item: Item, parent_dir: str) str[source]#
class pystac.layout.LayoutTemplate(template: str, defaults: Dict[str, str] | None = None)[source]#

Represents a template that can be used for deriving paths or other information based on properties of STAC objects supplied as a template string.

Template strings use variables that can be pulled out of Catalogs, Collections and Items. The variable names can represent properties on the object itself, or keys in the dictionaries of the properties or extra_fields on the object (if they exist). The search order is as follows:

  • The object’s attributes

  • Keys in the properties attribute, if it exists.

  • Keys in the extra_fields attribute, if it exists.

Some special keys can be used in template variables:

Template variable

Meaning

year

The year of an Item’s datetime, or start_datetime if datetime is null

month

The month of an Item’s datetime, or start_datetime if datetime is null

day

The day of an Item’s datetime, or start_datetime if datetime is null

date

The date (iso format) of an Item’s datetime, or start_datetime if datetime is null

collection

The collection ID of an Item’s collection.

The forward slash (/) should be used as path separator in the template string regardless of the system path separator (thus both in POSIX-compliant and Windows environments).

Examples:

# Uses the year, month and day of the item
template = LayoutTemplate("${year}/${month}/${day}")

# Uses a custom extension properties found on in the item properties.
template = LayoutTemplate("${landsat:path}/${landsat:row}")

# Uses the collection ID and a common metadata property for an item.
template = LayoutTemplate("${collection}/${common_metadata.license}")
Parameters:
  • template – The template string to use.

  • defaults – A dictionary of template vars to values. These values will be used in case a value cannot be derived from a stac object.

ITEM_TEMPLATE_VARS = ['date', 'year', 'month', 'day', 'collection']#
defaults: Dict[str, str]#

A dictionary of template vars to values. These values will be used in case a value cannot be derived from a stac object.

get_template_values(stac_object: STACObject) Dict[str, Any][source]#

Gets a dictionary of template variables to values derived from the given stac_object. If the template vars cannot be found in the stac object, and defaults was supplied to this template, a default value is used; if there is no default then this will raise an error.

Parameters:

stac_object – The STACObject to derive template variable values from.

Returns:

A dictionary with keys being the template variables and values being the respective values based on the given stac object.

Return type:

[dict]

Raises:

pystac.TemplateError – If a value for a template variable cannot be derived from the stac object and there is no default, this error will be raised.

substitute(stac_object: STACObject) str[source]#

Substitutes the values derived from get_template_values() into the template string for this template.

Parameters:

stac_object – The STACObject to derive template variable values from.

Returns:

The original template supplied to this LayoutTemplate with template variables replaced by the values derived from this stac object.

Return type:

str

Raises:

pystac.TemplateError – If a value for a template variable cannot be derived from the stac object and there is no default, this error will be raised.

template: str#

The template string to use.

template_vars: List[str]#

List of template vars to use when templating.

exception pystac.layout.TemplateError(*args, **kwargs)[source]#

DEPRECATED.

Deprecated since version 1.7.0: Use pystac.errors.TemplateError instead.

Exception thrown when an error occurs during converting a template string into data for LayoutTemplate

class pystac.layout.TemplateLayoutStrategy(catalog_template: str | None = None, collection_template: str | None = None, item_template: str | None = None, fallback_strategy: HrefLayoutStrategy | None = None)[source]#

Layout strategy that can take strings to be supplied to LayoutTemplate s to derive paths. Template strings can be supplied for catalogs, collections and items separately. If no template is supplied, a fallback layout strategy is supplied, which defaults to the BestPracticesLayoutStrategy.

All templated paths will be joined with the parent directory of the stac object.

Parameters:
  • catalog_template – The template string to use for catalog paths. Must be a valid template string that can be used by LayoutTemplate

  • collection_template – The template string to use for collection paths. Must be a valid template string that can be used by LayoutTemplate

  • item_template – The template string to use for item paths. Must be a valid template string that can be used by LayoutTemplate

  • fallback_strategy – The fallback strategy to use if a template is not provided. Defaults to BestPracticesLayoutStrategy

catalog_template: LayoutTemplate | None#

The template string to use for catalog paths. Must be a valid template string that can be used by LayoutTemplate.

collection_template: LayoutTemplate | None#

The template string to use for collection paths. Must be a valid template string that can be used by LayoutTemplate.

fallback_strategy: HrefLayoutStrategy#

The fallback strategy to use if a template is not provided. Defaults to BestPracticesLayoutStrategy.

get_catalog_href(cat: Catalog, parent_dir: str, is_root: bool) str[source]#
get_collection_href(col: Collection, parent_dir: str, is_root: bool) str[source]#
get_item_href(item: Item, parent_dir: str) str[source]#
item_template: LayoutTemplate | None#

The template string to use for item paths. Must be a valid template string that can be used by LayoutTemplate.