Custom query instance nodes specification

TypeScript type: CustomQueryInstanceNodesSpecification.

Returns nodes for instances returned by a provided ECSQL query.

Attributes

Attribute: queries

Specifications of queries used to create the content. Query specifications define the actual results of the specification. There are 2 types of supported query specifications:

• String query specification
• ECProperty value query specification.

The queries used in the specifications must return ECClassId and ECInstanceId columns, e.g.:

SELECT e.ECClassId, e.ECInstanceId FROM bis.Element e WHERE e.Parent.Id = 0x123

Note: sorting and grouping happens after results of multiple query specifications are aggregated.

String query specification

The specification contains an ECSQL query which is used to query for instances.

// The ruleset has a root nodes' specification that uses a given query to get all `bis.Model` instances.
const ruleset: Ruleset = {
  id: "example",
  rules: [
    {
      ruleType: "RootNodes",
      specifications: [
        {
          specType: "CustomQueryInstanceNodes",
          queries: [
            {
              specType: "String",
              class: { schemaName: "BisCore", className: "Model" },
              query: `SELECT * FROM bis.Model`,
            },
          ],
        },
      ],
    },
  ],
};

ECProperty value query specification

The specification specifies the name of the parent node instance property whose value is the ECSQL used to query for instances.

Precondition: can be used only if parent node is ECInstance node. If there is no immediate parent instance node, the rules engine walks up the hierarchy until it finds one. If that fails, this specification has no effect.

// The ruleset has a root nodes' specification that returns `MyDomain.MyParentElement` nodes. It also has
// a children specification that returns `MyDomain.MyChildElement` children for `MyDomain.MyParentElement`
// parent nodes using `ChildrenQuery` property value of the parent element.
const ruleset: Ruleset = {
  id: "example",
  rules: [
    {
      ruleType: "RootNodes",
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: { schemaName: "MyDomain", classNames: ["MyParentElement"], arePolymorphic: true },
          groupByClass: false,
        },
      ],
    },
    {
      ruleType: "ChildNodes",
      condition: `ParentNode.IsOfClass("MyParentElement", "MyDomain")`,
      specifications: [
        {
          specType: "CustomQueryInstanceNodes",
          queries: [
            {
              specType: "ECPropertyValue",
              class: { schemaName: "MyDomain", className: "MyChildElement" },
              parentPropertyName: "ChildrenQuery",
            },
          ],
        },
      ],
    },
  ],
};

Attribute: hideNodesInHierarchy

When true, instances nodes produced by this specification are omitted and their children appear one hierarchy level higher. Note: only instance nodes are hidden - grouping nodes are not affected by this attribute.

// The ruleset contains a root node specification for `bis.PhysicalModel` nodes which are grouped by class and hidden. This
// means class grouping nodes are displayed, but instance nodes are hidden and instead their children are displayed. The
// children are determined by another rule.
const ruleset: Ruleset = {
  id: "example",
  rules: [
    {
      ruleType: "RootNodes",
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: { schemaName: "BisCore", classNames: ["PhysicalModel"], arePolymorphic: true },
          hideNodesInHierarchy: true,
        },
      ],
    },
    {
      ruleType: "ChildNodes",
      specifications: [
        {
          specType: "CustomNode",
          type: "child",
          label: "Child",
        },
      ],
    },
  ],
};

hideNodesInHierarchy: false	hideNodesInHierarchy: true

Attribute: hideIfNoChildren

Specifies whether nodes created through this specification should be hidden if they have no child nodes.

// The ruleset contains root node specifications for two custom nodes which are only
// displayed if they have children. One of them has children and the other - not, so
// only one of them is displayed
const ruleset: Ruleset = {
  id: "example",
  rules: [
    {
      ruleType: "RootNodes",
      specifications: [
        {
          specType: "CustomNode",
          type: "2d",
          label: "2d Elements",
          hideIfNoChildren: true,
        },
        {
          specType: "CustomNode",
          type: "3d",
          label: "3d Elements",
          hideIfNoChildren: true,
        },
      ],
    },
    {
      ruleType: "ChildNodes",
      condition: `ParentNode.Type = "2d"`,
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: { schemaName: "BisCore", classNames: ["GeometricElement2d"], arePolymorphic: true },
        },
      ],
    },
    {
      ruleType: "ChildNodes",
      condition: `ParentNode.Type = "3d"`,
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: { schemaName: "BisCore", classNames: ["GeometricElement3d"], arePolymorphic: true },
        },
      ],
    },
  ],
};

hideIfNoChildren: false	hideIfNoChildren: true

Attribute: hideExpression

When specified ECExpression evaluates to true, nodes produced by this specification are omitted and their children appear one hierarchy level higher.

// The ruleset contains root node specifications for two custom nodes which are only
// displayed if they have children. One of them has children and the other - not, so
// only one of them is displayed
const ruleset: Ruleset = {
  id: "example",
  rules: [
    {
      ruleType: "RootNodes",
      specifications: [
        {
          specType: "CustomNode",
          type: "2d",
          label: "2d Elements",
          hideExpression: `ThisNode.HasChildren = FALSE`,
        },
        {
          specType: "CustomNode",
          type: "3d",
          label: "3d Elements",
          hideExpression: `ThisNode.HasChildren = FALSE`,
        },
      ],
    },
    {
      ruleType: "ChildNodes",
      condition: `ParentNode.Type = "2d"`,
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: { schemaName: "BisCore", classNames: ["GeometricElement2d"], arePolymorphic: true },
        },
      ],
    },
    {
      ruleType: "ChildNodes",
      condition: `ParentNode.Type = "3d"`,
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: { schemaName: "BisCore", classNames: ["GeometricElement3d"], arePolymorphic: true },
        },
      ],
    },
  ],
};

hideExpression evaluates to false	hideExpression evaluates to true

Attribute: suppressSimilarAncestorsCheck

Specifies whether similar ancestor nodes' checking should be suppressed when creating nodes based on this specification. See more in Infinite Hierarchies Prevention page.

// The ruleset contains a root node specification that returns the root `bis.Subject` node. Also, there are two
// child node rules:
// - For any `bis.Model` node, return its contained `bis.Element` nodes.
// - For any `bis.Element` node, return its children `bis.Model` nodes.
// Children of the root `bis.Subject` are all in the single `bis.RepositoryModel` and some of their children are in the same
// `bis.RepositoryModel` as their parent. This means the `bis.RepositoryModel` node has to be repeated in the hierarchy, but
// that wouldn't happen due to duplicate nodes prevention, unless the `suppressSimilarAncestorsCheck` flag is set.
const ruleset: Ruleset = {
  id: "example",
  rules: [
    {
      ruleType: "RootNodes",
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: { schemaName: "BisCore", classNames: ["Subject"] },
          instanceFilter: `this.ECInstanceId = 1`,
          groupByClass: false,
          groupByLabel: false,
        },
      ],
    },
    {
      ruleType: "ChildNodes",
      condition: `ParentNode.IsOfClass("Model", "BisCore")`,
      specifications: [
        {
          specType: "RelatedInstanceNodes",
          relationshipPaths: [
            {
              relationship: { schemaName: "BisCore", className: "ModelContainsElements" },
              direction: "Forward",
            },
          ],
          groupByClass: false,
          groupByLabel: false,
        },
      ],
    },
    {
      ruleType: "ChildNodes",
      condition: `ParentNode.IsOfClass("Element", "BisCore")`,
      specifications: [
        {
          specType: "RelatedInstanceNodes",
          relationshipPaths: [
            [
              {
                relationship: { schemaName: "BisCore", className: "ElementOwnsChildElements" },
                direction: "Forward",
              },
              {
                relationship: { schemaName: "BisCore", className: "ModelContainsElements" },
                direction: "Backward",
              },
            ],
          ],
          suppressSimilarAncestorsCheck: true,
          groupByClass: false,
          groupByLabel: false,
        },
      ],
    },
  ],
};

Attribute: priority

Controls the order in which specifications are handled — specification with higher priority value is handled first. If priorities are equal, the specifications are handled in the order they appear in the ruleset.

// This ruleset produces a list of `bis.PhysicalModel` and `bis.SpatialCategory` instances and groups them by
// class. "Spatial Category" group will appear first because it has been given a higher priority value.
const ruleset: Ruleset = {
  id: "example",
  rules: [
    {
      ruleType: "RootNodes",
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          priority: 1,
          classes: { schemaName: "BisCore", classNames: ["PhysicalModel"], arePolymorphic: true },
        },
        {
          specType: "InstanceNodesOfSpecificClasses",
          priority: 2,
          classes: { schemaName: "BisCore", classNames: ["SpatialCategory"], arePolymorphic: true },
        },
      ],
    },
  ],
};

Attribute: doNotSort

By default, nodes are sorted by their display label. This attribute allows suppressing sorting of nodes returned by this specification, which can substantially improve performance when large numbers of nodes are involved. With this attribute set to true, the order of returned nodes is undefined.

// The ruleset has a specification that returns unsorted `bis.Model` nodes - the order is undefined.
const ruleset: Ruleset = {
  id: "example",
  rules: [
    {
      ruleType: "RootNodes",
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: [{ schemaName: "BisCore", classNames: ["Model"], arePolymorphic: true }],
          doNotSort: true,
        },
      ],
    },
  ],
};

Attribute: groupByClass

Controls whether returned instances should be grouped by ECClass.

// The ruleset contains a specification that returns `bis.Model` nodes without grouping them
// by class.
const ruleset: Ruleset = {
  id: "example",
  rules: [
    {
      ruleType: "RootNodes",
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: [{ schemaName: "BisCore", classNames: ["Model"], arePolymorphic: true }],
          groupByClass: false,
        },
      ],
    },
  ],
};

groupByClass: false	groupByClass: true

Attribute: groupByLabel

Controls whether returned instances should be grouped by label.

Label grouping node is created only if all of these conditions match:

• There are at least two nodes with the same label.
• There's at least one sibling node with a different label.

// The ruleset contains a specification that returns `meta.ECPropertyDef` nodes without grouping them
// by label.
const ruleset: Ruleset = {
  id: "example",
  rules: [
    {
      ruleType: "RootNodes",
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: [{ schemaName: "ECDbMeta", classNames: ["ECPropertyDef"] }],
          groupByLabel: false,
        },
      ],
    },
  ],
};

groupByLabel: false	groupByLabel: true

Attribute: hasChildren

Generally, when a node is created, the rules engine has to determine whether it has children before returning it. This requires evaluating child node rules and, usually, executing additional queries. This attribute allows telling the engine that nodes created by this specification always or never have children, which may substantially improve performance of creating nodes in cases when getting child nodes is expensive.

In case when the attribute value "lies":

• When set to Always, the returned nodes always have hasChildren flag set to true. Requesting children for such nodes returns empty list. It's up to the UI component to handle the case of parent node saying it has children but data source not returning any.

• When set to Never, the returned nodes always have hasChildren set to false. Requesting children for such nodes returns empty list even if there are child node rules that define children for it.

// This ruleset produces a hierarchy of a single root node that hosts a list of `Model` instances. Assuming all
// iModels contain at least one model, the result of this ruleset can be computed quicker by setting
// `hasChildren` attribute to `"Always"`.
const ruleset: Ruleset = {
  id: "example",
  rules: [
    {
      ruleType: "RootNodes",
      specifications: [
        {
          specType: "CustomNode",
          type: "T_ROOT_NODE",
          label: "My Root Node",
          hasChildren: "Always",
        },
      ],
    },
    {
      ruleType: "ChildNodes",
      condition: `ParentNode.Type="T_ROOT_NODE"`,
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: [{ schemaName: "BisCore", classNames: ["Model"], arePolymorphic: true }],
        },
      ],
    },
  ],
};

hasChildren: "Always"	hasChildren: "Never"

Attribute: relatedInstances

Specifications of related instances that can be used when creating the nodes. There are several use cases when this is useful:

• When there's a need to only load instances that have a related instance. Providing a related instance specification with isRequired set to true filters-out the instances that don't have the related instance.

• When there's a need to filter instances by a related instance value. The alias attribute may then be used in the instanceFilter attribute to reference related instance property values.

• When there's a need to group by related instance property values. Related instance classes are included when looking for grouping rules, which allows using related instance values for property grouping.

• When there's a need to customize nodes based on related instance property values. Related instance classes are included when looking for customization rules, which allows referencing related instances and their properties in customization rule ECExpressions by their alias.

// The ruleset contains a root nodes' specification that returns nodes for `bis.Elements` that are in
// a category containing "a" in either `UserLabel` or `CodeValue` property.
const ruleset: Ruleset = {
  id: "example",
  rules: [
    {
      ruleType: "RootNodes",
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: [{ schemaName: "BisCore", classNames: ["GeometricElement3d"], arePolymorphic: true }],
          relatedInstances: [
            {
              relationshipPath: [
                {
                  relationship: { schemaName: "BisCore", className: "GeometricElement3dIsInCategory" },
                  direction: "Forward",
                },
              ],
              alias: "category",
              isRequired: true,
            },
          ],
          instanceFilter: `category.UserLabel ~ "%a%" OR category.CodeValue ~ "%a%"`,
        },
      ],
    },
  ],
};

Attribute: nestedRules

Specifications of nested child node rules that allow creating child nodes without the need of supplying a condition to match the parent node.

This is useful when the same instance node at different hierarchy levels needs to have different child nodes. Specifying a child node rule at the root level with condition to match the instance ECClass makes the rule create children for all nodes of that ECClass. When that's not desired, different child node rules may be specified as nested rules for specifications that return instance nodes of the same ECClass - that makes them have different children.

// The ruleset contains two root nodes' specifications:
// - The first one returns `bis.SpatialCategory` nodes
// - The second one returns `bis.PhysicalModel` nodes and also has a nested child node rule
//   that creates a static "child" node.
// Nested rules apply only to nodes created by the same specification, so the static "child"
// node is created only for the `bis.PhysicalModel`, but not `bis.SpatialCategory`.
const ruleset: Ruleset = {
  id: "example",
  rules: [
    {
      ruleType: "RootNodes",
      specifications: [
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: [{ schemaName: "BisCore", classNames: ["SpatialCategory"] }],
          groupByClass: false,
        },
        {
          specType: "InstanceNodesOfSpecificClasses",
          classes: [{ schemaName: "BisCore", classNames: ["PhysicalModel"] }],
          groupByClass: false,
          nestedRules: [
            {
              ruleType: "ChildNodes",
              specifications: [
                {
                  specType: "CustomNode",
                  type: "T_CHILD",
                  label: "child",
                },
              ],
            },
          ],
        },
      ],
    },
  ],
};

Last Updated: 03 April, 2024