farmOS/docs/development/module/services.md

Services

farmOS provides some services that encapsulate common logic like querying logs and getting an asset's current location. Some of these services are documented here.

Asset location service

Service name: asset.location

The asset location service provides methods that encapsulate the logic for determining an asset's location and geometry.

Note that these methods do not perform access checking on any of the assets or logs used to determine location. It is up to downstream code to ensure access controls are respected.

Methods:

isLocation($asset) - Check if an asset is a location. Returns a boolean.

isFixed($asset) - Check if an asset is fixed. Returns a boolean.

hasLocation($asset) - Check if an asset is located within other location assets. Returns a boolean.

hasGeometry($asset) - Check if an asset has geometry. Returns a boolean.

getLocation($asset) - Get location assets that an asset is located within. Returns an array of asset entities.

getGeometry($asset) - Get an asset's geometry. Returns a Well-Known Text string.

getMovementLog($asset) - Find the latest movement log that references an asset. Returns a log entity, or NULL if no logs were found.

setIntrinsicGeometry($asset, $wkt) - Set an asset's intrinsic geometry, given a string in Well-Known Text format.

getAssetsByLocation($locations) - Get assets that are in locations.

Example usage:

// Get an asset's current geometry.
$geometry = \Drupal::service('asset.location')->getGeometry($asset);

Asset inventory service

Service name: asset.inventory

The asset inventory service provides methods that encapsulate the logic for determining an asset's inventory.

Note that these methods do not perform access checking on any of the assets or logs used to determine inventory. It is up to downstream code to ensure access controls are respected.

Methods:

getInventory($asset, $measure = '', $units = 0) - Get inventory summaries for an asset. Returns an array of arrays with the following keys: measure, value, units. This can be optionally filtered by $measure (string) and $units (term ID).

Example usage:

// Get summaries of all inventories for an asset.
$all_inventory = \Drupal::service('asset.inventory')->getInventory($asset);

// Get the current inventory for a given measure (string) and units (term id).
$gallons_of_fertilizer = \Drupal::service('asset.inventory')->getInventory($asset, 'volume', 123);

Field factory service

Service name: farm_field.factory

The field factory service provides two methods to make the process of creating Drupal entity base and bundle field definitions easier and more consistent in farmOS. This is used by modules that add fields to entity types.

Base fields are added to all bundles of a given entity type (eg: all logs). Bundle fields are only added to specific bundles (eg: only "Input" logs).

Using this service is optional. It simply generates instances of Drupal core's BaseFieldDefinition class or the Entity API module's BundleFieldDefinition class, with farmOS-specific opinions to help enforce some consistency among farmOS core and contrib modules. You can create instances of these field definition classes directly instead of using the farmOS field factory service. Or you can take the object produced by the service and customize it further using standard Drupal field definition methods. This service is provided only as a shortcut.

For more information on Drupal core's field definition API, see Drupal FieldTypes, FieldWidgets and FieldFormatters

Methods:

baseFieldDefinition($options) - Generates a base field definition, given an array of options (see below).

bundleFieldDefinition($options) - Generates a bundle field definition, given an array of options (see below).

Options:

Both methods expect an array of field definition options. These include:

• type (required) - The field data type. Each type may require additional options. Supported types include:
  • boolean - True/false checkbox.
  • entity_reference - Reference other entities. Additional options:
    • target_type (required) - The entity type to reference (eg: asset, log, plan)
    • target_bundle (optional) - The allowed target bundle. For example, a target_type of asset and a target_bundle of animal would limit references to animal assets.
    • auto_create (optional) Only used when target_type is set to taxonomy_term. If auto_create is set, term references will be created automatically if the term does not exist.
  • file - File upload.
  • fraction - High-precision decimal number storage.
  • geofield - Geometry on a map.
  • image - Image upload.
  • list_string - Select list with allowed values. Additional options:
    • allowed_values - An associative array of allowed values.
    • allowed_values_function - The name of a function that returns an associative array of allowed values.
  • string_long - Unformatted text field of unlimited length.
  • text_long - Formatted text field of unlimited length.
  • timestamp - Date and time.
• label - The field label.
• description - The field description.
• required - Whether the field is required.
• multiple - Whether the field should allow multiple values. Defaults to FALSE.
• cardinality - How many values are allowed (eg: 1 for single value fields, -1 for unlimited values). This is an alternative to multiple, and will take precedence if it is set. Defaults to 1.

Other options are available for more advanced use-cases. Refer to the FarmFieldFactory class to understand how they work.

For more information and example code, see Adding fields.

Group membership service

Service name: group.membership

The group membership service provides methods that encapsulate the logic for determining an asset's group membership. This is provided by the optional Group Asset module, and will only be available if that module is installed.

Note that these methods do not perform access checking on any of the assets or logs used to determine group membership. It is up to downstream code to ensure access controls are respected.

Methods:

hasGroup($asset) - Check if an asset is a member of a group. Returns a boolean.

getGroup($asset) - Get group assets that an asset is a member of. Returns an array of asset entities.

getGroupAssignmentLog($asset) - Find the latest group assignment log that references an asset. Returns a log entity, or NULL if no logs were found.

getGroupMembers($groups, $recurse) - Get assets that are members of groups, optionally recursing into child groups.

Example usage:

// Get the groups that an asset is a member of.
$groups = \Drupal::service('group.membership')->getGroup($asset);

Log query service

Service name: farm.log_query

The log query service is a helper service for building a standard log database query. This is primarily used to query for the "latest" log of an asset. The asset location and group membership services use this.

Note that you must set specify whether or not you want access checking to be performed on the queried logs by running the accessCheck() method on the query object that is returned. This will determine whether or not logs that the current user does not have access to will be filtered out. If you are trying to find the "latest" log of an asset for a particular purpose, filtering out logs can cause inconsistent results, so typically accessCheck(FALSE) is necessary. It is the responsibility of the code that uses this service to understand the security implications of the data this returns, and perform additional access checking if necessary.

Methods:

getQuery($options) - Builds a log database query.

The query will be sorted by log timestamp and id, descending.

It accepts a keyed array of options:

• type (string) - Filter by log type.
• timestamp (Unix timestamp) - Filter to logs by timestamp. Only logs with a timestamp less than or equal to this will be included.
• status (string) - Filter by log status.
• asset (asset entity) - Filter to logs that reference a particular asset.
• limit (int) - Only include this many results.

Example usage:

// Find the latest "movement" log for an asset.
$options = [
  'asset' => $asset,
  'timestamp' => \Drupal::time()->getCurrentTime(),
  'status' => 'done',
  'limit' => 1,
];
$query = \Drupal::service('farm.log_query')->getQuery($options);
$query->condition('is_movement', TRUE);
$query->accessCheck(FALSE);
$log_ids = $query->execute();

// Load the first log.
$log = \Drupal::service('entity_type.manager')->getStorage('log')->load(reset($log_ids));