Predicates provide a way to define complex expressions for querying resources or specifying conditional triggers for API Extensions.
The queryable APIs support ad-hoc filtering of resources through flexible predicates.
They do so via the
where query parameter that accepts a predicate expression to determine whether a specific resource representation should be included in the result.
API Extensions support predicates via the
condition field in the ExtensionTrigger.
Please note that the Query Predicates syntax differs from the ones used for other predicate types, most notably the predicates used to define discount targets.
The structure of predicates and the names of the fields follow the structure and naming of the fields in the documented response representation of the respective query results.
API endpoints that support Query Predicates allow passing input variables as separate HTTP query parameters.
Query Predicates by example
on standard and Custom Fields
// Compare a field's value to a given valuename = "Peter" // For exact match to "Peter". This does not perform substring match.name != "Peter"age < 42age > 42age <= 42age >= 42age <> 42// Combine any two conditional expressions in a logical conjunction / disjunctionname = "Peter" and age < 42name = "Peter" or age < 42// Negate any other conditional expressionnot (name = "Peter" and age < 42)// Check whether a field's value is or is not contained in// a specified set of values.age in (42, 43, 44)age not in (42, 43, 44)// to be noted: 'in' is much more efficient than several '='// prefer:name in ("Peter", "Barbara")// to:name = "Peter" or name = "Barbara"// Check whether an array contains all or any of a set of valuestags contains all ("a", "b", "c")tags contains any ("a", "b", "c")// Check whether an array is emptytags is empty// Check whether a field exists & has a non-null valuename is definedname is not defined// Descend into nested objectsdog(age < 7 and name = "Beethoven")// Descend into nested arrays of objectscities(zip > 10000 and zip < 20000)// Query GeoJSON field within a circle// The two first parameters are the longitude and latitude of the circle's center.// The third parameter is the radius of the circle in meter.geoLocation within circle(13.37770, 52.51627, 1000)// To query for resources with Custom Fields// enclose the Custom Field with 'custom(fields(<name>:<value>))'// where <name> is as defined in the FieldDefinition and <value> is compliant to the FieldType of the Custom Field// name: "description", FieldType: CustomFieldStringTypecustom(fields(description="example description"))
on Product Attributes
// Query for ProductProjections with attribute values// - to get all results add a predicate of the same form, but starting with 'masterVariant' instead of 'variants'// - to query for Products instead enclose the examples with 'masterData(current(<example>))' or 'masterData(staged(<example>))'// ---------------------------// for missing attributevariants(not(attributes(name="attribute-name")))// for single attribute value of TextTypevariants(attributes(name="attribute-name" and value="attribute-value"))// for multiple attribute values of TextType with same namevariants(attributes(name="attribute-name" and value in ("attribute-value-1", "attribute-value-2")))// for single attribute value of LTextTypevariants(attributes(name="attribute-name" and value(en="attribute-value")))// for multiple attribute values of LTextType with same namevariants(attributes(name="attribute-name" and value(en="english-value" or de="german-value")))// for EnumType or LocalizableEnumTypevariants(attributes(name="attribute-name" and value(key="enum-key")))// for MoneyType (currencyCode is required)variants(attributes(name="attribute-name" and value(centAmount=999 and currencyCode="EUR")))// for MoneyType with centAmount within a specific range (currencyCode is required)variants(attributes(name="attribute-name" and value(centAmount > 999 and centAmount < 1001 and currencyCode="EUR")))// for NumberTypevariants(attributes(name="attribute-name" and value=999))// for NumberType with value within a specific rangevariants(attributes(name="attribute-name" and value > 999 and value < 1001 ))// for DateType, TimeType, or DateTimeTypevariants(attributes(name="attribute-name" and value="attribute-value"))// for DateType, TimeType, or DateTimeType with a value within a specific rangevariants(attributes(name="attribute-name" and value > "value-start" and value < "value-end"))// for ReferenceTypevariants(attributes(name="attribute-name" and value(typeId="reference-type-id" and id="reference-id")))
A query endpoint usually restricts predicates to only be allowed on a specified subset of a resource representation's fields. The documentation of the endpoint lists fields that can be used for constructing predicates.
If multiple predicates are specified via multiple
where query parameters,
the individual predicates are combined in a logical conjunction, just as if
they had been specified in a single
where query parameter and combined with
Note: The encoding of the predicates is
UTF-8 and the predicate must be URL-encoded in the HTTP request.
Example predicate for querying Products:
# decoded predicatemasterData(current(slug(en="peter-42") and name(en="Peter")))# URL-encoded predicatemasterData%28current%28slug%28en%3D%22peter-42%22%29%20and%20name%28en%3D%22Peter%22%29%29%29
Query predicates support the use of input variables to simplify working with query strings that contain dynamic values. Using input variables also eases log analysis because identical query use cases have identical
where query parameter values.
Inside the Query Predicate string, references to input variables must be prefixed with a colon
All input variables referenced in the Query Predicate must be added to the URI as separate HTTP query parameters whose names must be prefixed with
var.. The same input parameter can be passed multiple times to be used as an array of values.
The actual names of the input variables must consist of alphanumeric characters only.
Input variable examples
HTTP query using one input variable:
# decoded:?where=firstName = :name&var.name=Peter# URL-encoded:?where=firstName%20%3D%20%3Aname&var.name=Peter
HTTP query using an array input variable:
# decoded:?where=masterVariant(sku in :skus) or variants(sku in :skus)&var.skus=sku1&var.skus=sku2&var.skus=sku3# URL-encoded:?where=masterVariant%28sku%20in%20%3Askus%29%20or%20variants%28sku%20in%20%3Askus%29&var.skus=sku1&var.skus=sku2&var.skus=sku3
Referencing input variables in Query Predicates:
// Compare a field's value to a given input variable valuename = :name// Check whether a field's value is or is not contained in// a specified set of input variable values.age in :agesage in (:age1, :age2, :age3)age not in :agesage not in (:age1, :age2, :age3)// Check whether an array contains all or any of a set of input variable valuestags contains all :tagstags contains all (:tag1, :tag2, :tag3)tags contains any :tagstags contains any (:tag1, :tag2, :tag3)// Referencing an input variable multiple timesmasterVariant(sku in :skus) or variants(sku in :skus)
Query predicates are translated to database queries whose efficiency depends on how well the database can use indexes.
Indexes are managed automatically by commercetools Composable Commerce. Some indexes are present on all projects, others are added dynamically. For example, if you add a custom field to your carts and start querying it, the system will add an index to the project to improve performance if it meets criteria like query frequency.
The automatic index creation needs to collect a significant amount of data to not optimize for outlier scenarios. That's why it can take up to two weeks before a new index is added.
Efficient queries can be fast on extremely large datasets and inefficient queries can be fast on small datasets, too. But inefficient query patterns on large datasets cause long-running and resource-intensive queries. Such queries can affect the overall performance of a Project.
Not all Query Predicates can be easily supported with an index, so if possible avoid the following patterns on large datasets:
- Indexes on Product Attributes on the Products and Product Projections endpoints are not provided. Use the Product Projection Search endpoint instead or try to narrow down your result set with an additional restriction, for example on the
- Fields nested inside arrays - the index becomes inefficient if it contains too many entries. For example,
variants(attributes(name = "attribute-name" and value = "attribute-value")).
- Querying for a condition that is true for the majority of resources, for example
custom(state = "Done").
- Negations, such as
state != "Open"or
state is not defined.
emptyoperator on arrays, such as
lineItems is emptyor
lineItems is not empty.
The following patterns are supporting efficient query execution:
- Non-nested fields that heavily reduce the subset of resources to filter, for example
custom(state = "WaitingForExternalApproval")(assuming there are few resources waiting for external approval)
- If possible, prefer equality over other operators. For example,
(state = "Done" or state = "Canceled)"can be faster than
(state != "Open")in a query that contains further expressions.
- Queries on Orders, Carts, Customers, etc. may be fast in the beginning, but slow down over time as your Project grows. Include a time range, for example
lastModifiedAt > $1-week-ago and ...(replace
$1-week-agowith an actual date). Try defaulting the time range to the smallest value that is acceptable for the use case. Alternatively, try filtering by a field value that naturally only occurs in recently created resources.
Sorting and query performance
Sorting can also be supported by indexes. For best performance, the same index can be used for filtering and sorting. If possible, re-use a field from the Query Predicate for sorting.
For example, if your filter query is
lastModifiedAt > $1-week-ago, sorting on
lastModifiedAt is advised since it is more performant than sorting on a different field, like
Deactivate calculating the total
Deactivating the calculation of the
total field in the PagedQueryResult will improve the performance of the query. Whenever the
total is not needed, deactivate its calculation by using the query parameter
Using predicates in conditional API Extensions
Besides querying resources, the predicates syntax also allows you to define complex expressions for the conditional execution of API Extensions.
A few minor differences aside, the behavior of the language and the operators used are the same for both querying APIs and defining API Extension conditions. The features not supported in conditional API Extensions are:
- Input variables
Using predicates to react to change in data
In addition to the existing set of predicates, conditional API Extensions support the ability to check for changes to a resource's properties. For example, if your Extension is configured to be triggered for update actions to Carts, you can check whether the update action contains changes to the Cart's shipping information. By using the
has changed operator, you can ensure that the Extension is called only when certain properties are updated in the update action triggering the Extension. Given a valid predicate, the
has changed operator will evaluate to true for all create actions.
The negation of
has changed is also supported. Using
has not changed will ensure that the Extension only triggers when certain properties do not change during the update action. Given a valid predicate, the
has not changed operator will evaluate to false for all create actions.
Below are a few examples on how the
has changed and
has not changed operators behave during create and update actions:
// Evaluates to true if the name field is updated during the API callname has changed// Evaluates to true if the name field is not updated during the API callname has not changed// Evaluates to true if the resource is created with the name attributename has changed// Evaluates to true if the quantities of existing Line Items change, or if new Line Items are addedlineItems(quantity has changed)// Evaluates to false if the field shoeSize does not existshoeSize has changed
This feature requires a comparison between the current and previous versions of a resource during an update or create action. Therefore, the
has changed and
has not changed operators are only supported when defining API Extension conditions.
Fur further examples on how Query Predicates can be used in the context of API Extensions, you can find a detailed tutorial here.