FindEntity

FindEntity Command

This could either return the expected number of property values or entity ids as a list or apply operations like count, average, sum on them and return that. There can be multiple entities found after applying all the search criteria (in that order). If no search conditions are provided, you can read all entities in the system. By giving a local id, it is possible to associate result of the search with that value and use it later. The local id allows an application to chain this call with following operations.

Tip:: choose the first property constraint carefully in order to restrict the most number of entity returns since that one is potentially applied on an existing index. The other constraints are applied sequentially on the returned result set.

Parameters

• [optional] class: name of entity class.
• [optional] _ref: local id to be used as reference for a given entity.
• [optional] unique: [True or False]. Indicates whether a single element is expected to match that condition.

Blocks

• [optional] results
• [optional] constraints
• [optional] link

If the constraints block is skipped, all entities with the given class are returned. If the class is skipped, all entities ever added to the system are returned.

If the requested response was a list with some number of given property keys Indicates how many values matched the search condition. If limit is provided, the number of entries returned will be n <= m (which is the actually matched quantity)

Examples

// To find an entity of class Visit where its "start" property is on or
// after midnight of Aug 7 2017

"FindEntity": {
    "_ref" : 1,
    "class": "Visit",
    "constraints" : {
        "start": [ ">=", "Mon Aug 7 00:00:00 PDT 2017" ],
    }
}


/*
* In order to follow connections from existing entities in the system,
* we can first use the FindEntity call described above to get a reference
* and then use that as a starting point for expanding on to the entities we
* want to get to: e.g in the two calls here, we first find the Visit entity
* and then look for areas in that visit (connected to the Visit entity by the
* connection VisitedDuring). No constraints are placed on the
* areas returned. The results block indicates that we want to see the
* names of those areas.
*/

"FindEntity": {
    "_ref" : 2,

    "class": "Area",
    "link": {
        "direction": "out",
        "class": "VisitedDuring",
        "ref": 1,
    },
    "results": {
        "list": "Name"
    }
}