Schema Checker

• Expression: @<schema>
• Operand: string constant

NOTE

When combined with property filtering, i.e., when @<schema> && <property> == 123 is shortened as @<schema>.<property> == 123, the <property> cannot be _id or _uuid

NOTE

The @<schema> and @<schema>.<property> that appear in an Ultipa filter find the metadata of a specific schema and/or property, which is different than the @<schema> and @<schema>.<property> that appear in some other chain statements that find a specific schema and/or property in a graph model. Please read GraphSet | Schema | Property for more information.

Sample graph: (to be used for the following examples)

Run below UQLs one by one in an empty graphset to create graph data: ```customlang___fold__lang_uql create().node_schema("professor").node_schema("student") create().node_property(@*, "age", int32).node_property(@*, "email", string) insert().into(@professor).nodes([{_id:"P001",_uuid:1,age:53,email:"[email protected]"},{_id:"P002",_uuid:2,age:27,email:"[email protected]"}]) insert().into(@student).nodes([{_id:"S001",_uuid:3,age:27,email:"[email protected]"},{_id:"S002",_uuid:4,age:20,email:"[email protected]"},{_id:"S003",_uuid:5,age:25,email:"[email protected]"}]) ```

Schema

Example: Find nodes of @student

UQL
find().nodes({@student}) as n
return n{*} 

Result
|---------------- @student ---------------|
|  _id  | _uuid |  age  |       email     |
|-------|-------|-------|-----------------|
| S001  |   3   |  27   | [email protected]   |
| S002  |   4   |  20   | [email protected]     |
| S003  |   5   |  25   | [email protected]  |

Analysis: This filter is equivalent to {this.@ == "student"}

Schema & Property

Example: Find nodes of @student, whose age is 27

UQL
find().nodes({@student.age == 27}) as n
return n{*} 

Result
|---------------- @student ---------------|
|  _id  | _uuid |  age  |       email     |
|-------|-------|-------|-----------------|
| S001  |   3   |  27   | [email protected]   |

Analysis: This filter is equivalent to {@student && age == 27}.