GraphQueryStreamingResult | API Reference | ArcGIS Maps SDK for JavaScript 4.30

The result of a executeSearchStreaming() or executeQueryStreaming() on a knowledge graph service. Contains a readable stream of objects that match the search or query criteria. The readable stream must be decoded using a getReader() function in order to access the returned graph data.

See also

Examples

// sample executeSearchStreaming that would return a GraphQueryStreamingResult
KnowledgeGraphModule.executeSearchStreaming(
  knowledgeGraph,
  {
    searchQuery: "solar",
    typeCategoryFilter: "entity",
    returnSearchContext: false,
    start: 1, // index of the first record to return
    num: 200, // return 200 records.
    namedTypesFilter: ["Company", "Supplier", "Part"],
    idsFilter: ["{9D2D6AFD-41F1-49A4-8412-CACCC9906E88}",
                      "{25WNN24S-41F1-49A4-8412-ANIWN9906E88}",
                      "{NS51HE8D-41F1-49A4-8412-5HNIRH9906E8}"]
  }
).then((streamingSearchResult)=>{
  // the result of a streaming search is a readableStream which requires decoding.
  readStream(streamingSearchResult)
})

// the returned readable stream before decoding
{
  resultsRowsStream: {
    locked: true
  }
}

// sample streaming query using bind parameters
// to search for entities with a the `name` property that matches a specific string
// or have their geometry within a bounding box.
// get all parts bought by each supplier.
// query returns both the supplier and the part it buys.
const query = `MATCH (s:Supplier)-[:buys_part]-(p:Part) RETURN s,p`;

KnowledgeGraphModule.executeQueryStreaming(knowledgeGraph, query})
.then((streamingQueryResult)=>{
  // streaming query returns a readableStream which must be read to access the returned graph data
  readStream(streamingQueryResult);
})

// a function to read the readable stream returned from the above query
const readStream = async (streamingQueryResult) => {
  let time = Date.now();
  let reader = streamingQueryResult.resultRowsStream.getReader();
  try {
    while (true) {
      const { done, value } = await reader.read();
      if (done) {
        console.log(`Completed database requests: ${(Date.now() - time) / 1000} seconds`, value);
        break;
      }
      console.log(`Chunk returned in: ${(Date.now() - time) / 1000} seconds`, value);
      // use the results
      // list the parts bought by each supplier
      let supplierParts = {};
      // each element of the result array will contain one supplier and one part it buys
      for (var v in value){
        let supplier = value[v][0].properties.Name
        let part = value [v][1].properties.Name
        if(!(supplier in supplierParts)){
          supplierParts[supplier] = [];
        }
        // collect parts by supplier that buys them
        supplierParts[supplier].push(part);
        console.log(supplierParts);
        // result printed to the console: {Supplier 1:[Part1], Supplier 3:[Part2, Part3]}
    }
  } catch (err) {
    if (err.name === "AbortError") {
      console.log("Request aborted as expected");
    } else {
      throw err;
    }
  }
};

// sample result of streaming search result chunk read and printed to the console.
// the reader will continue to return chunks until the stream is complete
// and all matching results are returned

"Streaming chunk returned in: 0.082 seconds"
[
  [{
    "declaredClass": "esri.rest.knowledgeGraph.Entity",
    "properties": {
      "Name": "Suncommon",
      "Employee_Count": 400,
      "energyType": "solar"
    },
    "typeName": "Company",
    "id": "{25WNN24S-41F1-49A4-8412-ANIWN9906E88}"
  }],
  [{
    "declaredClass": "esri.rest.knowledgeGraph.Entity",
    "properties": {
      "Name": "Quality Solar Supply",
      "Supplier_code": "158B",
      "City": "New Orleans",
    },
    "typeName": "Supplier",
    "id": "{GE5G1E8D-41F1-49A4-8412-QNG5EG48SG8S}"
  }],
  [{
    "declaredClass": "esri.rest.knowledgeGraph.Entity",
    "properties": {
      "Name": "Solar panel",
      "panel_type": "Polycrystalline",
      "price_per_unit": 400
    },
    "typeName": "Part",
    "id": "{9D2D6AFD-41F1-49A4-8412-CACCC9906E88}",
  }]
]

Constructors

GraphQueryStreamingResult Constructor new GraphQueryStreamingResult(properties)

Parameter

properties Object

optional

See the properties for a full list of the properties that may be passed into the constructor.

Property Overview

Any properties can be set, retrieved or listened to. See the Working with Properties topic.

Show inherited properties

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Name	Type	Summary	Class
	String	The name of the class.	Accessor
	ReadableStream	Readable stream of objects matching executeSearchStreaming() or executeQueryStreaming() criteria.	GraphQueryStreamingResult

Property Details

declaredClass Inherited Property declaredClass Stringreadonly Inherited from Accessor

The name of the class. The declared class name is formatted as esri.folder.className.

resultRowsStream Property resultRowsStream ReadableStream

Readable stream of objects matching executeSearchStreaming() or executeQueryStreaming() criteria. Requires decoding using the getReader() method.

Example

// example of result decoding.
// execute streaming query on a knowledge graph
kgModule.executeQueryStreaming(
  kg,
  {
    openCypherQuery: "MATCH (n) RETURN n LIMIT 500",
  }
).then((streamingQueryResult) => {
  readStream(streamingQueryResult);
})

//read the ReadableStream result
const readStream = async (streamingQueryResult) => {
  let time = Date.now();
  // create new stream reader
  let reader = streamingQueryResult.resultRowsStream.getReader();
  try {
  // while the stream is returning data
    while (true) {
      const { done, value } = await reader.read();
      // the stream has finished retrieving all matching records from the database
      if (done) {
        console.log("Client Query stream completed");
        break;
      }
      // do something with the result records returned in each chunk
      console.log(
        `Client Query Result at Time ${Date.now() - time}:`,
        value
      );
    }
    // if stream is aborted by user return message, otherwise throw error
  } catch (err) {
    if (err.name === "AbortError") {
      console.log("Request aborted as expected");
    } else {
      throw err;
    }
  }
};

Method Overview

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Return Type	Summary	Class
	Adds one or more handles which are to be tied to the lifecycle of the object.	Accessor
Boolean	Returns true if a named group of handles exist.	Accessor
	Removes a group of handles owned by the object.	Accessor

Method Details

addHandles Inherited Method addHandles(handleOrHandles, groupKey) Inherited from Accessor

Adds one or more handles which are to be tied to the lifecycle of the object. The handles will be removed when the object is destroyed.

// Manually manage handles
const handle = reactiveUtils.when(
  () => !view.updating,
  () => {
    wkidSelect.disabled = false;
  },
  { once: true }
);

this.addHandles(handle);

// Destroy the object
this.destroy();

Parameters

handleOrHandles WatchHandle|WatchHandle []

Handles marked for removal once the object is destroyed.

groupKey *

optional

Key identifying the group to which the handles should be added. All the handles in the group can later be removed with Accessor.removeHandles(). If no key is provided the handles are added to a default group.

hasHandles Inherited Method hasHandles(groupKey){Boolean} Inherited from Accessor

Returns true if a named group of handles exist.

Parameter

groupKey *

optional

A group key.

Returns

Type	Description
Boolean	Returns `true` if a named group of handles exist.

Example

// Remove a named group of handles if they exist.
if (obj.hasHandles("watch-view-updates")) {
  obj.removeHandles("watch-view-updates");
}

removeHandles Inherited Method removeHandles(groupKey) Inherited from Accessor

Removes a group of handles owned by the object.

Parameter

groupKey *

optional

A group key or an array or collection of group keys to remove.

Example

obj.removeHandles(); // removes handles from default group

obj.removeHandles("handle-group");
obj.removeHandles("other-handle-group");