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$savedfilter

Functionality​

Definition​

The $savedfilter endpoint allows you to save the filter defined by $filter when creating an entity set. This ensures that even if the entity set is removed from the server's cache, it can be recreated with the same filter.

Syntax​

To save a filter when creating an entity set, use the following format:

GET /rest/{{dataClass}}?$filter="{{filterExpression}}"&$savedfilter="{{filterExpression}}"&$method=entityset

To retrieve the entity set with the saved filter:

GET /rest/{{dataClass}}/$entityset/{{entitySetID}}?$savedfilter="{{filterExpression}}"

Supported Formats​

The $savedfilter parameter accepts a filter expression that matches the one used in $filter.

Detailed Behavior​

Using the $savedfilter Parameter​

When an entity set is created with a saved filter, the following occurs:

  • The filter is stored with the entity set.

  • If the entity set is removed from the cache, it can be recreated using the saved filter.

  • The new default timeout for the recreated entity set is 10 minutes.

Combining with Other Parameters​

The $savedfilter parameter can be combined with other parameters to enhance and secure the filtering of entity sets:

  • $filter: Define the initial filter criteria and save it using $savedfilter for consistency in future requests.

  • $orderby: Combine with $savedorderby to save and apply sorting criteria along with the filter.

  • $top/$limit and $skip: Navigate through the filtered entity set while maintaining the saved filter.

  • $expand: Include related data in the filtered results, ensuring the filter criteria are consistently applied.

  • $attributes: Specify which attributes to include in the filtered results, preserving the filter criteria.

  • $method=entityset: Create an entity set with a saved filter, allowing for consistent retrieval of filtered data.

  • $compute: Apply computations on the filtered dataset while ensuring the filter criteria are maintained.

  • $entityset: Use the saved filter when accessing entity sets to maintain the filtering consistency.

  • $queryplan: Analyze the query plan for the saved filter to understand and optimize its performance.

  • $querypath: Trace the execution path of the query with the saved filter to identify optimization opportunities.

Use Cases​

Creating an Entity Set with a Saved Filter​

To create an entity set and save the filter:

Request:

GET /rest/People?$filter="employer.name=Apple"&$savedfilter="employer.name=Apple"&$method=entityset

Response:

{
    "__ENTITYSET": "/rest/People/$entityset/CC6B48EDBFD64CD694F8EFBFC93F73FC",
    "__DATACLASS": "People",
    "__entityModel": "People",
    "__GlobalStamp": 0,
    "__COUNT": 13,
    "__FIRST": 0,
    "__ENTITIES": [ ... ],
    "__SENT": 13
}

Retrieving an Entity Set with a Saved Filter​

To retrieve the entity set using the saved filter:

Request:

GET /rest/People/$entityset/CC6B48EDBFD64CD694F8EFBFC93F73FC?$savedfilter="employer.name=Apple"

Response:

{
    "__DATACLASS": "People",
    "__entityModel": "People",
    "__GlobalStamp": 0,
    "__COUNT": 13,
    "__FIRST": 0,
    "__ENTITIES": [ ... ],
    "__SENT": 13
}

Recreating an Entity Set After Timeout​

If the entity set is removed from the cache due to timeout, it can be recreated with the saved filter:

Request:

GET /rest/People/$entityset/CC6B48EDBFD64CD694F8EFBFC93F73FC?$savedfilter="employer.name=Apple"

Best Practices​

  • Always Save Critical Filters: Save important filters to ensure entity sets can be recreated if they are removed from the cache.

  • Monitor Entity Set Usage: Regularly check the status of entity sets and recreate them as needed using saved filters.

  • Combine with $savedorderby: Use $savedorderby along with $savedfilter to maintain consistent ordering when recreating entity sets.

  • Set Appropriate Timeouts: Use the $timeout parameter to control the lifespan of cached entity sets and avoid unintentional deletions.