Guides / Managing results / Rules / Rules overview

Nov. 06, 2023

Implementing Rules

Using the Rules dashboard

Use the dashboard to familiarize yourself with Rules. The dashboard provides a responsive interface to create and configure your Rules. And importantly, test your choices using the dashboard’s live search interface.

You may never need to go beyond the dashboard if you have a few Rules or if they follow a clearly defined pattern.

In this way, you can consider the dashboard as a way to manage static Rules - Rules that remain in place for some time or whose effect is global and constant.

Go to the Rules tab for a selected index and click Add Rule. Here you can choose between two editors:

The Visual Editor allows you to pin results and hide results, boost categories, and filter results through a visual, guided user journey.
The Manual Editor supports more options but doesn’t offer an instant preview of the results.

Coding Rules with the API client

Coding the Rules using the Rules API becomes necessary when you need more programmatic control. This move from static to more dynamic Rules can arise for several reasons—like when you have too many to manage one-by-one or when you want to start building (and deleting) Rules based on the content of your database. You should use the API if your Rules change with every new update of your index or if you offer a frontend to manage your Rules.

You must set up your index for the API and then set up the Rules at indexing time.

How Rules works

The search engine adapts its behavior according to a Rule’s consequences. Rules are if-then configurations or condition/consequence pairs: the consequence applies to the returned results if the condition is satisfied. For example, a Rule with the condition “user’s query contains the word red” and the consequence “filter on the facet color:red”.

And that’s only one kind of consequence. As described in the overview and presented in technical detail below - many kinds of consequences adapt the search and alter the relevance.

Rules are processed at indexing time to prepare the index so that when someone performs a search, the data is ready for the if-then matching.

Keep in mind:

If the alternatives setting of a Rule is false, the condition must match the entire word (fully and exactly) for the Rule to be triggered.
All text matching is case insensitive.
Conditions can match on multiple phrases.
A Rule can have multiple conditions and multiple consequences.

Rules have no noticeable impact on performance. Most of the work happens during indexing, so they don’t affect search performance.

Turning Rules on and off

Turn a Rule off by setting its enabled flag to false. Rules that have been turned off remain in the index, meaning they’re still searchable, but ignored at query time. This is an alternative to deleting a Rule when you wish to turn it off temporarily.

For even more fine-grained control, you may specify validity windows on Rules (via the validity attribute). Rules with validity windows only apply during the specified time frames: they’re ignored the rest of the time. Rules with no time windows always apply. Like with the enabled flag, Rules with validity windows remain searchable all the time.

API overview

Pre-processing and post-processing

As suggested, Rules allows fine-tuning results for queries matching specific patterns. They do so in two complementary ways:

Query pre-processing. Rules may alter the query parameters - not only the query string but also features such filters and facets - before the query is processed.
Results post-processing. Rules may cause results (hits) to be ranked differently for specific queries. They may also add user data to the results.

Rules are complementary to the traditional ranking and textual relevance settings: while settings act globally on every search to an index, Rules act selectively.

Conditions and consequences

The general syntax is as follows:

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{
    "conditions": [{ /* What the query must match for the rule to be applied.  */ }],
    "consequence": { /* How the query will be modified if the rule is applied. */ }
}

Condition: What the query must match

Conditions identify query strings matching a specific pattern. If the query string matches all the Rule’s conditions, it activates the Rule for that search.

More precisely, a condition consists of:

An optional query pattern acting on the whole text query string, that is, the query search parameter.
Optional anchoring defining how the Rule’s query pattern compares to user queries.
Optional filters, which must match the filters applied with the query. These can be filters or facetFilters, but not numericFilters, tagFilters, nor optionalFilters.
An optional context must match a context supplied at query time with the ruleContexts parameter
Optionally enabled alternatives, which indicates whether synonyms and plurals of the query pattern are treated as matches.

Consequence: Modify the query

A Rule’s consequence can be one or more actions:

Add query parameters
Automatic facet filter
Automatic optional facet filter
Remove or replace a word from the query string
Replace the query string entirely
Promote or hide specific hits
Return user data.

Conditions - adapting the query

A rule can have any number of conditions:

If a rule has no conditions, it applies to every search.
If a rule has more than one condition, it applies when any condition matches.

For more information about multiple conditions, see Rule structure

Rule query pattern

The query pattern is the most crucial part of the Rule’s condition. It consists of a sequence of tokens, treated as a phrase. All tokens must appear contiguously and in the specified order.

The allowed token types are:

Literal: matches a word. The matching is case insensitive. If a Rule’s alternatives setting is true, then matching considers typo tolerance, plurals, and synonyms. If you set ignorePlurals to true or synonyms to false, your alternatives setting is ignored.
Facet value placeholder: matches any value of a given facet in the same index.

You must declare the facet in attributesForFaceting. Matching is case insensitive. Contrary to literals, facet values may be phrases.

The pattern is implicitly a phrase. The order of words matters: foo bar and bar foo aren’t identical patterns.

The pattern also has an anchoring type, depending on whether its boundaries (beginning, end) must coincide with the boundaries of the query string:

starts with: the pattern must match the words at the beginning of the query string, but there may be extra words at the end
ends with: the pattern must match the words at the end of the query string, but there may be extra words at the beginning
contains: the pattern must match any contiguous sequence of words of the query string.

Escape characters within a pattern

If you want to declare a Rule with a pattern that contains a colon (:), or any special character (}, {, \), you need to escape the character. For example, to set your query pattern to “thrones: episode”, you need to escape the : (“thrones\:episode”). The first \ is for JSON and the second is for the Rules engine.

Filters can trigger Rules

filters or facetFilters can trigger Rules. The primary goal of this condition is to create Rules that are triggered on specific category pages or when a user applies specific filters.

If a Rule’s condition has only filters and not query pattern nor context, the engine applies the Rule’s consequences. The engine applies the Rule’s consequences if a condition only has filters: no query patterns or context. If a condition also has query patterns or context, those must match for the Rule to be triggered.

To use an attribute in a Rule condition with filters, you must first declare it in attributesForFaceting.

A single Rule per filter value

Just like only a single Rule can be triggered per word in the query, only a single Rule can be triggered per applied filter. For example:

Rule A has the filter brand:Nike as its condition
Rule B has the filter brand:Nike and the query “shoes” as its condition
If the query is “shoes” and the filter brand:Nike is applied, only Rule B is triggered.
If the query is anything other than “shoes” and the filter brand:Nike is applied, only Rule A is triggered.

This follows the same precedence logic applied on Rules on queries and contexts.

Matches must be exact

A Rule with filter values in the condition triggers only when the search contains that value just for that filter. For example, if a Rule’s condition contains "filters": "brand:Nike", this Rule triggers if only the value Nike is selected in the filter brand. The engine doesn’t trigger the Rule for a query filtered on brand:Nike OR brand:Supreme.

If a condition has multiple filters, all applied filters must match exactly to trigger the Rule. For example, if the Rule condition is "filters": "brand:Nike AND color:red", then the engine triggers this Rule if only the value Nike is selected in the brand filter and only the value red is selected in the color filter. The Rule isn’t triggered if only Nike is selected without red, and it doesn’t trigger if brand:Nike and color:red OR color:blue are selected.

Only the filtering attributes in the condition matter

If a Rule’s condition includes the filter brand:Nike and no other filters, the engine only considers the brand attribute’s applied filter values to decide whether to trigger the Rule.

For example, if a query filters on brand:Nike AND color:red, that Rule doesn’t consider the value of the color filter because it’s not part of the condition. The engine triggers the Rule since brand is filtered on Nike.

Multiple filtering attributes

If a condition has multiple filters, the following applies:

Multiple values for the same attribute are grouped with an OR condition
Values for different attributes are grouped with an AND condition.

That means the engine interprets a condition containing brand:Supreme, brand:Nike, gender:men as (brand:Supreme OR brand:Nike) AND (gender:men).

In other words, the engine triggers the Rule if a user selects exactly the values (Supreme, Nike and men) in the filters on the frontend.

These conditions only hold if the frontend filters work with the same logic. For example, if a user filters on Nike, Supreme for brand, and red for color, the filtering logic follows the AND of ORs pattern: (brand:Nike OR brand:Supreme) AND color:red. Thus the filters are compatible with filtering conditions possible on Rules.

Filters in Rules’ conditions aren’t compatible with ORs of ANDs, ANDs of ANDs or ORs of ORs logic. For example, imagine a real estate search where a user filters for a two-bedroom apartment in Paris with a balcony and fireplace. In this use case, the desired logic would be ANDs of ANDs: bedrooms:2 AND (amenities:balcony AND amenities:fireplace) AND location:Paris. You can’t create a Rule with a condition to match this filtering.

Context

To narrow, customize, or make Rules query-independent, you can have a Rule respond to the ruleContexts parameter.

The contexts found in the ruleContexts of user searches are compared to the contexts you assign to your Rules.

Contexts passed as parameters during your search: doing so activates all Rules that share the context you passed. Activation means the Rule is considered not to have been applied. If your Rule’s condition only contains a context, the Rules consequence is applied to search results. If your Rule also contains a query pattern, that pattern must match for the consequence to be applied.

For example, you can define a set of Rules with the context “homepage” and pass the same context value along with any search that originates from your homepage. Now you have a set of Rules that apply to the homepage search, giving a more customized experience.

A Rule can have one context at most, but a search may have multiple contexts: these are treated as disjunctive (OR). When one or more contexts are specified at query time, Rules matching any of those contexts are activated.

General Rules are always activated.

The context’s primary goal is to conditionally enable Rules for specific search environments.

If present, the context is a string that must be passed at query time in the ruleContexts search parameter with the same value for the Rule to be triggered. Matching is case-sensitive.

The ruleContexts parameter allows you to enable multiple contexts simultaneously.

A Rule context must consist only of alphanumeric characters, hyphens, and underscores.

Consequence - adapting the results / relevance

A Rule’s consequence can be one or more actions.

Add query parameters

Any number of valid search parameters are supported. These parameters are literals (constants).

This consequence allows you to add or modify any search settings that can be changed when the query is sent to Algolia. Some settings that affect search, like Searchable Attributes, can only be modified at indexing time, meaning you can’t change them at query time.

Any parameter with search as part of its scope can be changed at query time.

One common example of a parameter that is useful to change at query time is filters. For example, when someone searches “tablet”, you want to show not only tablets (products with ‘tablets’ in their categories attribute) but also laptops used as tablets (products with ‘hybrids’ in their categories attribute). To do this in the dashboard, click Add Query Parameter when adding a consequence for your Query Rule, and add the following JSON into the editor:

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{
  "filters": "categories:tablets OR categories:hybrids"
}

You can also add filters with the API.

Automatically transform a word or group of words into a facet filter if it matches a value in a given facet. A user enters “red”, which is also a value in the color facet. You can set up a Rule to transform red to behave like a filter.

Another approach would be to use the filters parameter (using the “add query parameters” Rule) but, with this approach, you must have one Rule per filter value. If you have 10 color values in your color facet, you must create 10 Rules, one for each color.

It’s more powerful to use automatic faceting: instead of creating 1 Rule for each color, you create 1 Rule per facet. Whether the user types “blue” or “red”, this single Rule will apply, it also applies to new colors added to the facet.

When the pattern matches multiple values of the same facet, filters can be either conjunctive (AND, default) or disjunctive (OR). By default, the filters are combined with an AND operator. However, if you specify the filter to be disjunctive, an OR operator is used instead. In both cases, relationships to other filters in the query will always be conjunctive (AND).

You can also specify a score for the created filter, mainly useful for optional facet filters (see below).

For example, to automatically filter on the brand facet, using OR in case of multiple occurrences:

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{
  "conditions": [
    {
      "pattern": "{facet:brand}"
    }
  ],
  "consequence": {
      "params": {
          "automaticFacetFilters": [
              {
                  "facet": "brand",
                  "disjunctive": "true"
              }
          ]
      }
  }
}

And if you want to reverse the logic to exclude the captured facet for example, you can use the negative field and set it to true.

Same as automaticFacetFilters, but the filters are optional. Behaves like optionalFilters.

Remove or replace a word from the query string

Removing or replacing words is achieved by specifying a list of edits to be applied to the query string. An edit can either:

Remove a word (or facet placeholder)
Replace a word (or facet placeholder) with another word

For example, the Rule below specifies that when matching foo bar, the search engine should remove the word foo and the word bar should be replaced with baz:

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{
    "condition": [
      {
        "pattern": "foo bar"
      }
    ],
    "consequence": {
        "params": {
            "query": {
                "edits": [
                    {
                        "type": "remove",
                        "delete": "foo"
                    },
                    {
                        "type": "replace",
                        "delete": "bar",
                        "insert": "baz"
                    }
                ]
            }
        }
    }
}

Words that are removed or replaced from the query string are still highlighted or showing in the snippets in the query’s results, so it’s not misleading for the user.

Replace the query string entirely

To replace the query string entirely, specify a new string for the query parameter, as you would do for any other search parameters:

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{
    "condition": [
      {
        "pattern": "original query that will be replaced"
      }
    ],
    "consequence": {
        "params": {
            "query": "new text to be searched"
        }
    }
}

Replacing and removing a word are mutually exclusive Rules. It may also have an impact on subsequent Rules (see Matching algorithm).

Promote or hide specific hits

One or more objects from the same index, identified by their objectID, are promoted to specific positions in the results list or removed from them. This promotion works seamlessly with Algolia’s built-in pagination, mingling promoted hits with regular hits and removing hidden hits while keeping pages the same size.

Hit promotion is detailed below.

Return user data

User data is returned in a dedicated userData array. If multiple Rules are applied, each set of user data is appended to this array. User data can be used to display specific information that doesn’t affect pagination.

How To Add Banners To Results With `userData`

Some final considerations

Hit promotion’s effect on relevance

You can only promote objects coming from the same index. Promoted objects have to be explicitly identified by their objectID.

A promoted object will always be considered a hit, even if it doesn’t match the query. If it would have matched the query, it’s removed from its original position and inserted at its promoted position, even if the original position would have been better than the promoted position. In other words, promoted hits can also be “demoted”. For performance reasons, promoted positions are restricted to the range [0, 300] (keep in mind that positions are zero-based).

Inside the same Rule, each promoted object must have a different promoted position. If promoted objects from two distinct Rules are triggered for the same query:

Any duplicates are merged using the best position.
If the resulting positions conflict between distinct objects, objects are shifted down until a free slot is found.
All regular hits are shifted down as many times as necessary to ensure that all promoted objects get as close to their promoted position as possible (modulo conflicts between objects, as stated before).

Hidden objects are removed from the hits. The following hits are shifted up so that pagination works seamlessly.

Injecting user data

User data allows you to inject data inside the results that aren’t in the index, and as such, don’t compete with other hits for pagination. A typical use-case would be to display a banner on top of the result list.

User data can be any JSON object. The API doesn’t interpret user data.

If you want to keep your analytics data for longer, upgrade your plan or contact the Algolia support team.

Importing and exporting

You can import and export Rules from the Algolia dashboard.

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