QuerySpec

Some Management APIs include the ability to use a so-called QuerySpec to restrict the returns of the API. Certain settings can be made via parameters so that the result is limited and more specific.

Supported Management APIs

The following Management-APIs support using the QuerySpec, for example:

• /assets/request

• /policydefinitions/request

• /contractdefinitions/request

• /contractagreements/request

• /transferprocesses/request

• /catalog/request

These APIs either have the QuerySpec as a complete body or the QuerySpec is part of the body. The structure looks like this:

JSON

{
    "@type": "https://w3id.org/edc/v0.0.1/ns/QuerySpec",
    "https://w3id.org/edc/v0.0.1/ns/offset": 0,
    "https://w3id.org/edc/v0.0.1/ns/limit": 100,
    "https://w3id.org/edc/v0.0.1/ns/sortOrder": "DESC",
    "https://w3id.org/edc/v0.0.1/ns/sortField": "fieldName",
    "https://w3id.org/edc/v0.0.1/ns/filterExpression": [
        {
            "https://w3id.org/edc/v0.0.1/ns/operandLeft": "assetId",
            "https://w3id.org/edc/v0.0.1/ns/operator": "=",
            "https://w3id.org/edc/v0.0.1/ns/operandRight": "test"
        }
    ]
}

For example, pagination can be enabled by changing the number of returned data records using the limit parameter and setting the starting point using the offset or more specific filtering can be done using the filterExpression array.

Advanced Example Using the v3-API and a Custom Asset Property

POST {{Management-API}}/v3/assets/request

JSON

{
    "@type": "https://w3id.org/edc/v0.0.1/ns/QuerySpec",
    "https://w3id.org/edc/v0.0.1/ns/offset": 0,
    "https://w3id.org/edc/v0.0.1/ns/limit": 100,
    "https://w3id.org/edc/v0.0.1/ns/filterExpression": [
        {
            "https://w3id.org/edc/v0.0.1/ns/operandLeft": "asset:prop:type",
            "https://w3id.org/edc/v0.0.1/ns/operator": "=",
            "https://w3id.org/edc/v0.0.1/ns/operandRight": "data.core.digitalTwinRegistry"
        }
    ]
}

The POST body should of course be adapted to the specific situation as needed.

FAQ

Is there an implicit limit for returned records for query requests if no limit has been set in the QuerySpec?

Yes, if no limit has been specified in the QuerySpec, the connector outputs a maximum of 50 records. To exceed the limit, the limit must be added in the QuerySpec above this value. This can also be an extremely high value, such as 9999.

Is there anything I need to consider when setting the sortField?

An existing field must be set as the value of sortField if used; otherwise, the EDC will respond with an error code (500 Internal Server Error).