api_spec/Cursor.js.html - ignite-nodejs-thin-client - Git at Google

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     <section>
         <article>
             <pre class="prettyprint source linenums"><code>/*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You under the Apache License, Version 2.0
  * (the "License"); you may not use this file except in compliance with
  * the License.  You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 'use strict';

 const Errors = require('./Errors');
 const BinaryUtils = require('./internal/BinaryUtils');
 const BinaryObject = require('./BinaryObject');
 const BinaryReader = require('./internal/BinaryReader');
 const BinaryWriter = require('./internal/BinaryWriter');

 /**
  * Class representing a cursor to obtain results of SQL and Scan query operations.
  *
  * The class has no public constructor. An instance of this class is obtained
  * via query() method of {@link CacheClient} objects.
  * One instance of this class returns results of one SQL or Scan query operation.
  *
  * @hideconstructor
  */
 class Cursor {

     /**
      * Returns one element (cache entry - key-value pair) from the query results.
      *
      * Every new call returns the next cache entry from the query results.
      * If the method returns null, no more entries are available.
      *
      * @async
      *
      * @return {Promise&lt;CacheEntry>} - a cache entry (key-value pair).
      */
     async getValue() {
         if (!this._values || this._valueIndex >= this._values.length) {
             await this._getValues();
             this._valueIndex = 0;
         }
         if (this._values &amp;&amp; this._values.length > 0) {
             const value = this._values[this._valueIndex];
             this._valueIndex++;
             return value;
         }
         return null;
     }

     /**
      * Checks if more elements are available in the query results.
      *
      * @return {boolean} - true if more cache entries are available, false otherwise.
      */
     hasMore() {
         return this._hasNext ||
             this._values &amp;&amp; this._valueIndex &lt; this._values.length;
     }

     /**
      * Returns all elements (cache entries - key-value pairs) from the query results.
      *
      * May be used instead of getValue() method if the number of returned entries
      * is relatively small and will not cause memory utilization issues.
      *
      * @async
      *
      * @return {Promise&lt;Array&lt;CacheEntry>>} - all cache entries (key-value pairs)
      *   returned by SQL or Scan query.
      */
     async getAll() {
         let result = new Array();
         let values;
         do {
             values = await this._getValues();
             if (values) {
                 result = result.concat(values);
             }
         } while (this._hasNext);
         return result;
     }

     /**
      * Closes the cursor. Obtaining elements from the results is not possible after this.
      *
      * This method should be called if no more elements are needed.
      * It is not neccessary to call it if all elements have been already obtained.
      *
      * @async
      */
     async close() {
         // Close cursor only if the server has more pages: the server closes cursor automatically on last page
         if (this._id &amp;&amp; this._hasNext) {
             await this._socket.send(
                 BinaryUtils.OPERATION.RESOURCE_CLOSE,
                 async (payload) => {
                     await this._write(payload);
                 });
         }
     }

     /** Private methods */

     /**
      * @ignore
      */
     constructor(socket, operation, buffer, keyType = null, valueType = null) {
         this._socket = socket;
         this._operation = operation;
         this._buffer = buffer;
         this._keyType = keyType;
         this._valueType = valueType;
         this._id = null;
         this._hasNext = false;
         this._values = null;
         this._valueIndex = 0;
     }

     /**
      * @ignore
      */
     async _getNext() {
         this._hasNext = false;
         this._values = null;
         this._buffer = null;
         await this._socket.send(
             this._operation,
             async (payload) => {
                 await this._write(payload);
             },
             async (payload) => {
                 this._buffer = payload;
             });
     }

     /**
      * @ignore
      */
     async _getValues() {
         if (!this._buffer &amp;&amp; this._hasNext) {
             await this._getNext();
         }
         await this._read(this._buffer)
         this._buffer = null;
         return this._values;
     }

     /**
      * @ignore
      */
     async _write(buffer) {
         buffer.writeLong(this._id);
     }

     /**
      * @ignore
      */
     _readId(buffer) {
         this._id = buffer.readLong();
     }

     /**
      * @ignore
      */
     async _readRow(buffer) {
         const CacheEntry = require('./CacheClient').CacheEntry;
         return new CacheEntry(
             await BinaryReader.readObject(buffer, this._keyType),
             await BinaryReader.readObject(buffer, this._valueType));
     }

     /**
      * @ignore
      */
     async _read(buffer) {
         const rowCount = buffer.readInteger();
         this._values = new Array(rowCount);
         for (let i = 0; i &lt; rowCount; i++) {
             this._values[i] = await this._readRow(buffer);
         }
         this._hasNext = buffer.readBoolean();
     }
 }

 /**
  * Class representing a cursor to obtain results of SQL Fields query operation.
  *
  * The class has no public constructor. An instance of this class is obtained
  * via query() method of {@link CacheClient} objects.
  * One instance of this class returns results of one SQL Fields query operation.
  *
  * @hideconstructor
  * @extends Cursor
  */
 class SqlFieldsCursor extends Cursor {

     /**
      * Returns one element (array with values of the fields) from the query results.
      *
      * Every new call returns the next element from the query results.
      * If the method returns null, no more elements are available.
      *
      * @async
      *
      * @return {Promise&lt;Array&lt;*>>} - array with values of the fields requested by the query.
      *
      */
     async getValue() {
         return await super.getValue();
     }

     /**
      * Returns all elements (arrays with values of the fields) from the query results.
      *
      * May be used instead of getValue() method if the number of returned elements
      * is relatively small and will not cause memory utilization issues.
      *
      * @async
      *
      * @return {Promise&lt;Array&lt;Array&lt;*>>>} - all results returned by SQL Fields query.
      *   Every element of the array is an array with values of the fields requested by the query.
      *
      */
     async getAll() {
         return await super.getAll();
     }

     /**
      * Returns names of the fields which were requested in the SQL Fields query.
      *
      * Empty array is returned if "include field names" flag was false in the query.
      *
      * @return {Array&lt;string>} - field names.
      *   The order of names corresponds to the order of field values returned in the results of the query.
      */
     getFieldNames() {
         return this._fieldNames;
     }

     /**
      * Specifies types of the fields returned by the SQL Fields query.
      *
      * By default, a type of every field is not specified that means during operations the Ignite client
      * will try to make automatic mapping between JavaScript types and Ignite object types -
      * according to the mapping table defined in the description of the {@link ObjectType} class.
      *
      * @param {...ObjectType.PRIMITIVE_TYPE | CompositeType} fieldTypes - types of the returned fields.
      *   The order of types must correspond the order of field values returned in the results of the query.
      *   A type of every field can be:
      *   - either a type code of primitive (simple) type
      *   - or an instance of class representing non-primitive (composite) type
      *   - or null (means the type is not specified)
      *
      * @return {SqlFieldsCursor} - the same instance of the SqlFieldsCursor.
      */
     setFieldTypes(...fieldTypes) {
         this._fieldTypes = fieldTypes;
         return this;
     }

     /** Private methods */

     /**
      * @ignore
      */
     constructor(socket, buffer) {
         super(socket, BinaryUtils.OPERATION.QUERY_SQL_FIELDS_CURSOR_GET_PAGE, buffer);
         this._fieldNames = [];
     }

     /**
      * @ignore
      */
     async _readFieldNames(buffer, includeFieldNames) {
         this._id = buffer.readLong();
         this._fieldCount = buffer.readInteger();
         if (includeFieldNames) {
             for (let i = 0; i &lt; this._fieldCount; i++) {
                 this._fieldNames[i] = await BinaryReader.readObject(buffer);
             }
         }
     }

     /**
      * @ignore
      */
     async _readRow(buffer) {
         let values = new Array(this._fieldCount);
         let fieldType;
         for (let i = 0; i &lt; this._fieldCount; i++) {
             fieldType = this._fieldTypes &amp;&amp; i &lt; this._fieldTypes.length ? this._fieldTypes[i] : null;
             values[i] = await BinaryReader.readObject(buffer);
         }
         return values;
     }
 }

 module.exports.Cursor = Cursor;
 module.exports.SqlFieldsCursor = SqlFieldsCursor;
 </code></pre>
         </article>
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	<!DOCTYPE html>
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	<meta charset="utf-8">
	<title>JSDoc: Source: Cursor.js</title>

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	<script src="scripts/prettify/lang-css.js"> </script>
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	<h1 class="page-title">Source: Cursor.js</h1>






	<section>
	<article>
	<pre class="prettyprint source linenums"><code>/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	'use strict';

	const Errors = require('./Errors');
	const BinaryUtils = require('./internal/BinaryUtils');
	const BinaryObject = require('./BinaryObject');
	const BinaryReader = require('./internal/BinaryReader');
	const BinaryWriter = require('./internal/BinaryWriter');

	/**
	* Class representing a cursor to obtain results of SQL and Scan query operations.
	*
	* The class has no public constructor. An instance of this class is obtained
	* via query() method of {@link CacheClient} objects.
	* One instance of this class returns results of one SQL or Scan query operation.
	*
	* @hideconstructor
	*/
	class Cursor {

	/**
	* Returns one element (cache entry - key-value pair) from the query results.
	*
	* Every new call returns the next cache entry from the query results.
	* If the method returns null, no more entries are available.
	*
	* @async
	*
	* @return {Promise<CacheEntry>} - a cache entry (key-value pair).
	*/
	async getValue() {
	if (!this._values \|\| this._valueIndex >= this._values.length) {
	await this._getValues();
	this._valueIndex = 0;
	}
	if (this._values && this._values.length > 0) {
	const value = this._values[this._valueIndex];
	this._valueIndex++;
	return value;
	}
	return null;
	}

	/**
	* Checks if more elements are available in the query results.
	*
	* @return {boolean} - true if more cache entries are available, false otherwise.
	*/
	hasMore() {
	return this._hasNext \|\|
	this._values && this._valueIndex < this._values.length;
	}

	/**
	* Returns all elements (cache entries - key-value pairs) from the query results.
	*
	* May be used instead of getValue() method if the number of returned entries
	* is relatively small and will not cause memory utilization issues.
	*
	* @async
	*
	* @return {Promise<Array<CacheEntry>>} - all cache entries (key-value pairs)
	* returned by SQL or Scan query.
	*/
	async getAll() {
	let result = new Array();
	let values;
	do {
	values = await this._getValues();
	if (values) {
	result = result.concat(values);
	}
	} while (this._hasNext);
	return result;
	}

	/**
	* Closes the cursor. Obtaining elements from the results is not possible after this.
	*
	* This method should be called if no more elements are needed.
	* It is not neccessary to call it if all elements have been already obtained.
	*
	* @async
	*/
	async close() {
	// Close cursor only if the server has more pages: the server closes cursor automatically on last page
	if (this._id && this._hasNext) {
	await this._socket.send(
	BinaryUtils.OPERATION.RESOURCE_CLOSE,
	async (payload) => {
	await this._write(payload);
	});
	}
	}

	/** Private methods */

	/**
	* @ignore
	*/
	constructor(socket, operation, buffer, keyType = null, valueType = null) {
	this._socket = socket;
	this._operation = operation;
	this._buffer = buffer;
	this._keyType = keyType;
	this._valueType = valueType;
	this._id = null;
	this._hasNext = false;
	this._values = null;
	this._valueIndex = 0;
	}

	/**
	* @ignore
	*/
	async _getNext() {
	this._hasNext = false;
	this._values = null;
	this._buffer = null;
	await this._socket.send(
	this._operation,
	async (payload) => {
	await this._write(payload);
	},
	async (payload) => {
	this._buffer = payload;
	});
	}

	/**
	* @ignore
	*/
	async _getValues() {
	if (!this._buffer && this._hasNext) {
	await this._getNext();
	}
	await this._read(this._buffer)
	this._buffer = null;
	return this._values;
	}

	/**
	* @ignore
	*/
	async _write(buffer) {
	buffer.writeLong(this._id);
	}

	/**
	* @ignore
	*/
	_readId(buffer) {
	this._id = buffer.readLong();
	}

	/**
	* @ignore
	*/
	async _readRow(buffer) {
	const CacheEntry = require('./CacheClient').CacheEntry;
	return new CacheEntry(
	await BinaryReader.readObject(buffer, this._keyType),
	await BinaryReader.readObject(buffer, this._valueType));
	}

	/**
	* @ignore
	*/
	async _read(buffer) {
	const rowCount = buffer.readInteger();
	this._values = new Array(rowCount);
	for (let i = 0; i < rowCount; i++) {
	this._values[i] = await this._readRow(buffer);
	}
	this._hasNext = buffer.readBoolean();
	}
	}

	/**
	* Class representing a cursor to obtain results of SQL Fields query operation.
	*
	* The class has no public constructor. An instance of this class is obtained
	* via query() method of {@link CacheClient} objects.
	* One instance of this class returns results of one SQL Fields query operation.
	*
	* @hideconstructor
	* @extends Cursor
	*/
	class SqlFieldsCursor extends Cursor {

	/**
	* Returns one element (array with values of the fields) from the query results.
	*
	* Every new call returns the next element from the query results.
	* If the method returns null, no more elements are available.
	*
	* @async
	*
	* @return {Promise<Array<*>>} - array with values of the fields requested by the query.
	*
	*/
	async getValue() {
	return await super.getValue();
	}

	/**
	* Returns all elements (arrays with values of the fields) from the query results.
	*
	* May be used instead of getValue() method if the number of returned elements
	* is relatively small and will not cause memory utilization issues.
	*
	* @async
	*
	* @return {Promise<Array<Array<*>>>} - all results returned by SQL Fields query.
	* Every element of the array is an array with values of the fields requested by the query.
	*
	*/
	async getAll() {
	return await super.getAll();
	}

	/**
	* Returns names of the fields which were requested in the SQL Fields query.
	*
	* Empty array is returned if "include field names" flag was false in the query.
	*
	* @return {Array<string>} - field names.
	* The order of names corresponds to the order of field values returned in the results of the query.
	*/
	getFieldNames() {
	return this._fieldNames;
	}

	/**
	* Specifies types of the fields returned by the SQL Fields query.
	*
	* By default, a type of every field is not specified that means during operations the Ignite client
	* will try to make automatic mapping between JavaScript types and Ignite object types -
	* according to the mapping table defined in the description of the {@link ObjectType} class.
	*
	* @param {...ObjectType.PRIMITIVE_TYPE \| CompositeType} fieldTypes - types of the returned fields.
	* The order of types must correspond the order of field values returned in the results of the query.
	* A type of every field can be:
	* - either a type code of primitive (simple) type
	* - or an instance of class representing non-primitive (composite) type
	* - or null (means the type is not specified)
	*
	* @return {SqlFieldsCursor} - the same instance of the SqlFieldsCursor.
	*/
	setFieldTypes(...fieldTypes) {
	this._fieldTypes = fieldTypes;
	return this;
	}

	/** Private methods */

	/**
	* @ignore
	*/
	constructor(socket, buffer) {
	super(socket, BinaryUtils.OPERATION.QUERY_SQL_FIELDS_CURSOR_GET_PAGE, buffer);
	this._fieldNames = [];
	}

	/**
	* @ignore
	*/
	async _readFieldNames(buffer, includeFieldNames) {
	this._id = buffer.readLong();
	this._fieldCount = buffer.readInteger();
	if (includeFieldNames) {
	for (let i = 0; i < this._fieldCount; i++) {
	this._fieldNames[i] = await BinaryReader.readObject(buffer);
	}
	}
	}

	/**
	* @ignore
	*/
	async _readRow(buffer) {
	let values = new Array(this._fieldCount);
	let fieldType;
	for (let i = 0; i < this._fieldCount; i++) {
	fieldType = this._fieldTypes && i < this._fieldTypes.length ? this._fieldTypes[i] : null;
	values[i] = await BinaryReader.readObject(buffer);
	}
	return values;
	}
	}

	module.exports.Cursor = Cursor;
	module.exports.SqlFieldsCursor = SqlFieldsCursor;
	</code></pre>
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