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Property reference

You can refer to the properties of a vertex or an edge in WHERE and YIELD syntax.

Note

This function applies to native nGQL only.

Property reference for vertex

For source vertex

$^.<tag_name>.<prop_name>
Parameter Description
$^ is used to get the property of the source vertex.
tag_name is the tag name of the vertex.
prop_name specifies the property name.

For destination vertex

$$.<tag_name>.<prop_name>
Parameter Description
$$ is used to get the property of the destination vertex.
tag_name is the tag name of the vertex.
prop_name specifies the property name.

Property reference for edge

For user-defined edge property

<edge_type>.<prop_name>
Parameter Description
edge_type is the edge type of the edge.
prop_name specifies the property name of the edge type.

For built-in properties

Apart from the user-defined edge property, there are four built-in properties in each edge:

Parameter Description
_src source vertex ID of the edge
_dst destination vertex ID of the edge
_type edge type
_rank the rank value for the edge

Examples

The following query returns the name property of the player tag on the source vertex and the age property of the player tag on the destination vertex.

nebula> GO FROM "player100" OVER follow YIELD $^.player.name AS startName, $$.player.age AS endAge;
+--------------+--------+
| startName    | endAge |
+--------------+--------+
| "Tim Duncan" | 36     |
| "Tim Duncan" | 41     |
+--------------+--------+

The following query returns the degree property of the edge type follow.

nebula> GO FROM "player100" OVER follow YIELD follow.degree;
+---------------+
| follow.degree |
+---------------+
| 95            |
+---------------+

The following query returns the source vertex, the destination vertex, the edge type, and the edge rank value of the edge type follow.

nebula> GO FROM "player100" OVER follow YIELD follow._src, follow._dst, follow._type, follow._rank;
+-------------+-------------+--------------+--------------+
| follow._src | follow._dst | follow._type | follow._rank |
+-------------+-------------+--------------+--------------+
| "player100" | "player101" | 17           | 0            |
| "player100" | "player125" | 17           | 0            |
+-------------+-------------+--------------+--------------+

Legacy version compatibility

Nebula Graph 2.6.0 and later versions support the new Schema function. Similar statements as the above examples are written as follows in 3.0.1.

GO FROM "player100" OVER follow YIELD properties($^).name AS startName, properties($$).age AS endAge;
GO FROM "player100" OVER follow YIELD properties(edge).degree;
GO FROM "player100" OVER follow YIELD src(edge), dst(edge), type(edge), rank(edge);

In 3.0.1, Nebula Graph is still compatible with the old syntax.


Last update: July 20, 2022
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