Class SingleConnectedVertexLoader<TRetrievedItem>

The 1:1 connection loader.

This class aggregates multiple 1:1 connection retrievals into a single Gremlin query which allows optimizing database queries.

It is possible to aggregate multiple 1:1 connection retrievals if the following conditions are met:

relationship directions matches (in Gremlin there's no easy way to query both ingoing and outgoing edges at same time while applying different label filters to different directions);
destination vertices have same labels (since access rules are applies per destination vertex label).

At the same, multiple originating vertices UUIDs and edge labels could be queried at the same time.

Below is a list of examples of how queries could be merged:

Relationships	Could be aggregated
`Content --hasApprover-> User`, `Content --hasOwner-> User`	Yes
`Content --belongsTo-> Organisation`, `User --reportsTo-> Organisation`	Yes, edges directions and destinations matches
`Content --relatesTo-> User`, `Content --relatesTo-> Content`	No; destination labels differs.
`Content --relatesTo-> Content`, `Content <-relatesTo-- Content`	No; edges directions differs.

Mermaid

Retrieving 1:1 connections

%%{init:{"theme":"dark"}}%% sequenceDiagram participant Resolvers participant SingleConnectedVertexLoader participant Graph database Resolvers->>SingleConnectedVertexLoader: Retrieve connected vertex 1 SingleConnectedVertexLoader->>Resolvers: Promise Resolvers->>SingleConnectedVertexLoader: Retrieve connected vertex 2 SingleConnectedVertexLoader->>Resolvers: Promise Resolvers->>SingleConnectedVertexLoader: Retrieve connected vertex 3 SingleConnectedVertexLoader->>Resolvers: Promise activate SingleConnectedVertexLoader Note left of SingleConnectedVertexLoader: Aggregates requests until next event loop tick SingleConnectedVertexLoader->>Graph database: Retrieve connected vertices 1, 2, 3 Graph database->>SingleConnectedVertexLoader: Response Note left of SingleConnectedVertexLoader: Resolves Promises deactivate SingleConnectedVertexLoader SingleConnectedVertexLoader->>Resolvers: Connected vertex 1 SingleConnectedVertexLoader->>Resolvers: Connected vertex 2 SingleConnectedVertexLoader->>Resolvers: Connected vertex 3

%%{init:{"theme":"default"}}%% sequenceDiagram participant Resolvers participant SingleConnectedVertexLoader participant Graph database Resolvers->>SingleConnectedVertexLoader: Retrieve connected vertex 1 SingleConnectedVertexLoader->>Resolvers: Promise Resolvers->>SingleConnectedVertexLoader: Retrieve connected vertex 2 SingleConnectedVertexLoader->>Resolvers: Promise Resolvers->>SingleConnectedVertexLoader: Retrieve connected vertex 3 SingleConnectedVertexLoader->>Resolvers: Promise activate SingleConnectedVertexLoader Note left of SingleConnectedVertexLoader: Aggregates requests until next event loop tick SingleConnectedVertexLoader->>Graph database: Retrieve connected vertices 1, 2, 3 Graph database->>SingleConnectedVertexLoader: Response Note left of SingleConnectedVertexLoader: Resolves Promises deactivate SingleConnectedVertexLoader SingleConnectedVertexLoader->>Resolvers: Connected vertex 1 SingleConnectedVertexLoader->>Resolvers: Connected vertex 2 SingleConnectedVertexLoader->>Resolvers: Connected vertex 3

sequenceDiagram
    participant Resolvers
    participant SingleConnectedVertexLoader
    participant Graph database
    Resolvers->>SingleConnectedVertexLoader: Retrieve connected vertex 1
    SingleConnectedVertexLoader->>Resolvers: Promise
    Resolvers->>SingleConnectedVertexLoader: Retrieve connected vertex 2
    SingleConnectedVertexLoader->>Resolvers: Promise
    Resolvers->>SingleConnectedVertexLoader: Retrieve connected vertex 3
    SingleConnectedVertexLoader->>Resolvers: Promise
    activate SingleConnectedVertexLoader
    Note left of SingleConnectedVertexLoader: Aggregates requests until next event loop tick
    SingleConnectedVertexLoader->>Graph database: Retrieve connected vertices 1, 2, 3
    Graph database->>SingleConnectedVertexLoader: Response
    Note left of SingleConnectedVertexLoader: Resolves Promises
    deactivate SingleConnectedVertexLoader
    SingleConnectedVertexLoader->>Resolvers: Connected vertex 1
    SingleConnectedVertexLoader->>Resolvers: Connected vertex 2
    SingleConnectedVertexLoader->>Resolvers: Connected vertex 3

Type Parameters

TRetrievedItem extends EdgeAndVertex = EdgeAndVertex

Hierarchy

LoaderBase<SingleConnectedVertexLoaderDataLoaderId, SingleConnectedVertexLoaderDataItemId, TRetrievedItem, TRetrievedItem, ConnectedVertexLoaderTransformParams>
- SingleConnectedVertexLoader

Index

Constructors

constructor

new SingleConnectedVertexLoader<TRetrievedItem>(graphConnector: GraphConnector, schemaManager: SchemaManager): SingleConnectedVertexLoader<TRetrievedItem>
Type Parameters
- TRetrievedItem extends EdgeAndVertex<StoredKosmosItem, StoredKosmosItem> = EdgeAndVertex<StoredKosmosItem, StoredKosmosItem>
Parameters
- graphConnector: GraphConnector
- schemaManager: SchemaManager
Returns SingleConnectedVertexLoader<TRetrievedItem>
Overrides LoaderBase.constructor
- Defined in src/backends/dataLoaders/connectedVertices/SingleConnectedVertexLoader.ts:105

Properties

`Protected` graphConnector

graphConnector: GraphConnector

`Protected` schemaManager

schemaManager: SchemaManager

Methods

`Protected` buildDataLoader

buildDataLoader(context: KosmosUserContext<object>, __namedParameters: SingleConnectedVertexLoaderDataLoaderId): BatchLoader<SingleConnectedVertexLoaderDataItemId, TRetrievedItem>
Builds new DataLoader instance for 1:1 relationships of vertices.
Parameters
- context: KosmosUserContext<object>
  
  The user context.
- __namedParameters: SingleConnectedVertexLoaderDataLoaderId
Returns BatchLoader<SingleConnectedVertexLoaderDataItemId, TRetrievedItem>
Overrides LoaderBase.buildDataLoader
- Defined in src/backends/dataLoaders/connectedVertices/SingleConnectedVertexLoader.ts:120

clearCache

clearCache(context: KosmosUserContext<object>): void
Clears per-request data loaders cache.
Parameters
- context: KosmosUserContext<object>
  
  The user context.
Returns void
Inherited from LoaderBase.clearCache
- Defined in src/backends/dataLoaders/LoaderBase.ts:136

`Protected` getDataLoader

getDataLoader(context: KosmosUserContext<object>, params: SingleConnectedVertexLoaderDataLoaderId): KosmosDataLoader<SingleConnectedVertexLoaderDataItemId, TRetrievedItem>
Returns DataLoader instance.
Parameters
- context: KosmosUserContext<object>
  
  The user context.
- params: SingleConnectedVertexLoaderDataLoaderId
  
  Class specific params required to identify the DataLoader instance.
Returns KosmosDataLoader<SingleConnectedVertexLoaderDataItemId, TRetrievedItem>
Inherited from LoaderBase.getDataLoader
- Defined in src/backends/dataLoaders/LoaderBase.ts:87

`Protected` getDataLoadersMap

getDataLoadersMap(context: KosmosUserContext<object>): Map<undefined | string, KosmosDataLoader<TItemId, TRetrievedItem>>
Returns a map of DataLoaders for the given request.
Parameters
- context: KosmosUserContext<object>
  
  The user context.
Returns Map<undefined | string, KosmosDataLoader<TItemId, TRetrievedItem>>
Inherited from LoaderBase.getDataLoadersMap
- Defined in src/backends/dataLoaders/LoaderBase.ts:116

retrieveItem

retrieveItem(context: KosmosUserContext<object>, requestParams: SingleConnectedVertexLoaderDataLoaderId & SingleConnectedVertexLoaderDataItemId, transformParams?: ConnectedVertexLoaderTransformParams): Promise<null | TRetrievedItem>
Retrieves an item using DataLoader.

Returns
The class specific response type or NULL.
Parameters
- context: KosmosUserContext<object>
  
  The user context.
- requestParams: SingleConnectedVertexLoaderDataLoaderId & SingleConnectedVertexLoaderDataItemId
  
  Class specific request parameters.
- Optional transformParams: ConnectedVertexLoaderTransformParams
  
  Class specific response item transformation params.
Returns Promise<null | TRetrievedItem>
Inherited from LoaderBase.retrieveItem
- Defined in src/backends/dataLoaders/LoaderBase.ts:71

`Protected` serializeDataItemId

serializeDataItemId(__namedParameters: SingleConnectedVertexLoaderDataItemId): string
Produces string representation of data required to identify the DataLoader result row.

We're converting the object into array to:
1. enforce properties order;
2. only pick required properties and make sure there's nothing else passed in.
Parameters
- __namedParameters: SingleConnectedVertexLoaderDataItemId
Returns string
Overrides LoaderBase.serializeDataItemId
- Defined in src/backends/dataLoaders/connectedVertices/SingleConnectedVertexLoader.ts:209

`Protected` serializeDataLoaderId

serializeDataLoaderId(__namedParameters: SingleConnectedVertexLoaderDataLoaderId): string
Produces string representation of data required to identify the DataLoader instance.
Parameters
- __namedParameters: SingleConnectedVertexLoaderDataLoaderId
Returns string
Overrides LoaderBase.serializeDataLoaderId
- Defined in src/backends/dataLoaders/connectedVertices/SingleConnectedVertexLoader.ts:189

`Protected` storageName

storageName(): string
The unique name of the in-context storage used by this specific Loader service.

Returns string
Inherited from LoaderBase.storageName
- Defined in src/backends/dataLoaders/LoaderBase.ts:191

`Protected` transform

transform(edgeAndVertex: null | TRetrievedItem, context: KosmosUserContext<object>, dataLoaderId: SingleConnectedVertexLoaderDataLoaderId, __namedParameters?: {
runHooks: undefined | boolean;
}): Promise<null | TRetrievedItem>
The return value transformation callback.

Called after the item was retrieved from DataLoader. Child classes may override this method to perform transformation of the data being returned.
Parameters
- edgeAndVertex: null | TRetrievedItem
  
  The item being retrieved from DataLoader.
- context: KosmosUserContext<object>
  
  The user context.
- dataLoaderId: SingleConnectedVertexLoaderDataLoaderId
  
  The DataLoader identifier object which may contain properties used to initialize the Data Loader.
- __namedParameters: {
  runHooks: undefined | boolean;
  } = {}
  
  Class-specific transformation params.
  - runHooks: undefined | boolean
Returns Promise<null | TRetrievedItem>
Overrides LoaderBase.transform
- Defined in src/backends/dataLoaders/connectedVertices/SingleConnectedVertexLoader.ts:158

Class SingleConnectedVertexLoader<TRetrievedItem>

Mermaid

Retrieving 1:1 connections

Type Parameters

TRetrievedItem extends EdgeAndVertex = EdgeAndVertex

Hierarchy

Index

Constructors

Properties

Methods

Constructors

constructor

Type Parameters

TRetrievedItem extends EdgeAndVertex<StoredKosmosItem, StoredKosmosItem> = EdgeAndVertex<StoredKosmosItem, StoredKosmosItem>

Parameters

graphConnector: GraphConnector

schemaManager: SchemaManager

Returns SingleConnectedVertexLoader<TRetrievedItem>

Properties

Protected graphConnector

Protected schemaManager

Methods

Protected buildDataLoader

Parameters

context: KosmosUserContext<object>

__namedParameters: SingleConnectedVertexLoaderDataLoaderId

Returns BatchLoader<SingleConnectedVertexLoaderDataItemId, TRetrievedItem>

clearCache

Parameters

context: KosmosUserContext<object>

Returns void

Protected getDataLoader

Parameters

context: KosmosUserContext<object>

params: SingleConnectedVertexLoaderDataLoaderId

Returns KosmosDataLoader<SingleConnectedVertexLoaderDataItemId, TRetrievedItem>

Protected getDataLoadersMap

Parameters

context: KosmosUserContext<object>

Returns Map<undefined | string, KosmosDataLoader<TItemId, TRetrievedItem>>

retrieveItem

Returns

Parameters

context: KosmosUserContext<object>

requestParams: SingleConnectedVertexLoaderDataLoaderId & SingleConnectedVertexLoaderDataItemId

Optional transformParams: ConnectedVertexLoaderTransformParams

Returns Promise<null | TRetrievedItem>

Protected serializeDataItemId

Parameters

__namedParameters: SingleConnectedVertexLoaderDataItemId

Returns string

Protected serializeDataLoaderId

Parameters

__namedParameters: SingleConnectedVertexLoaderDataLoaderId

Returns string

Protected storageName

Returns string

Protected transform

Parameters

edgeAndVertex: null | TRetrievedItem

context: KosmosUserContext<object>

dataLoaderId: SingleConnectedVertexLoaderDataLoaderId

__namedParameters: { runHooks: undefined | boolean; } = {}

runHooks: undefined | boolean

Returns Promise<null | TRetrievedItem>

Settings

Member Visibility

Theme

`Protected` graphConnector

`Protected` schemaManager

`Protected` buildDataLoader

`Protected` getDataLoader

`Protected` getDataLoadersMap

`Optional` transformParams: ConnectedVertexLoaderTransformParams

`Protected` serializeDataItemId

`Protected` serializeDataLoaderId

`Protected` storageName

`Protected` transform

__namedParameters: {
runHooks: undefined | boolean;
} = {}