Filters And Aggregations

Filters

Filters allow to refine search results with exact match on specific fields. For example, if your data have a number field age, you can request results that have a specific exact value age=25.

In React-SearchKit, the query state contains a field called filters which contains the list of filters selected by the user.

Filters and Aggregations are fundamental concepts of Elasticsearch. However, they can be applied to any backend or REST APIs.

Aggregations

Aggregations can be defined as a set of complex summaries for the search results. Or in other words, a grouping of the search results to provide different statistics. For example, for the previous query age=25, the search results can include the list of all possible values for the field age and the number of results for each value.

For example, for each existing age value:

• 25: 3 results
• 26: 2 results
• 31: 18 results
• etc.

In Elasticsearch, there are several types of aggregations available. React-SearchKit comes out of the box with a component that implements Bucket Terms Aggregations, but any other aggregation should be easy to implement.

Bucket aggregations

The <BucketAggregation> component defines the name of the aggregation to request to the backend or Elasticsearch and the field to compute the aggregations on. For example:

<BucketAggregation
    title="All ages"
    agg={{
        field: 'age',
        aggName: 'ages_aggregation',
    }} />

It is your responsibility to create the search request to your backend taking into account the configured aggregations.

The results state should then contains aggregations results in the object aggregations. The <BucketAggregation> component expects the Elasticsearch format:

{
    "ages_aggregation": {
        "buckets": [
            {
                "key": 25,
                "doc_count": 3
            },
            {
                "key": 26,
                "doc_count": 2
            },
            {
                "key": 31,
                "doc_count": 18
            }
        ]
    }
}

The filters query state will contain the list of filters that the user has selected. Given that you can have multiple aggregations configured, each filter should be formatted as [ "<agg_name>", "<value>" ], for example:

{
    ...
    "filters": [
        [ "ages_aggregation", 25 ],
        [ "ages_aggregation", 31 ]
    ]
}