EJDB NodeJS ================================================ Installation -------------------------------- **System libraries:** * g++ * zlib On Debian/Ubuntu linux you can install it as follows: ```sh sudo apt-get install g++ zlib1g zlib1g-dev ``` **Installation from node package manager on linux/macos:** npm install ejdb **[Installing EJDB NodeJS module on windows](https://github.com/Softmotions/ejdb/blob/master/tcejdb/WIN32.md#ejdb-nodejs-module-installation)** EJDB NodeJS samples --------------------------------- * [node/samples](https://github.com/Softmotions/ejdb/tree/master/node/samples) * [node/tests](https://github.com/Softmotions/ejdb/tree/master/node/tests) * [nwk-ejdb-address-book](https://github.com/Softmotions/nwk-ejdb-address-book) EJDB NodeJS API ---------------------------------- ### EJDB.open(dbFile, openMode) Open database. Return database instance handle object.
Default open mode: `JBOWRITER | JBOCREAT`.
This is blocking function. __Arguments__ * {String} dbFile Database main file name * {Number} `[openMode=JBOWRITER | JBOCREAT]` Bitmast of open modes: - `JBOREADER` Open as a reader. - `JBOWRITER` Open as a writer. - `JBOCREAT` Create if db file not exists - `JBOTRUNC` Truncate db. --------------------------------------- ### close() Close database.
If database was not opened it does nothing.
This is blocking function. --------------------------------------- ### isOpen() Check if database in opened state. --------------------------------------- ### ensureCollection(cname, copts) Automatically creates new collection if it does't exists. Collection options `copts` applied only for newly created collection. For existing collections `copts` takes no effect. Collection options (copts): * cachedrecords : Max number of cached records in shared memory segment. Default: 0 * records : Estimated number of records in this collection. Default: 65535. * large : Specifies that the size of the database can be larger than 2GB. Default: false * compressed : If true collection records will be compressed with DEFLATE compression. Default: false.
This is blocking function. __Arguments__ * {String} cname Name of collection. * {Object} `[copts]` Collection options. --------------------------------------- ### dropCollection(cname, prune, cb) Drop collection. Call variations: dropCollection(cname) dropCollection(cname, cb) dropCollection(cname, prune, cb) __Arguments__ * {String} cname Name of collection. * {Boolean} `[prune=false]` If true the collection data will erased from disk. * {Function} `[cb]` Callback args: (error) --------------------------------------- ### save(cname, jsarr, cb) Save/update specified JSON objects in the collection. If collection with `cname` does not exists it will be created. Each persistent object has unique identifier (OID) placed in the `_id` property. If a saved object does not have `_id` it will be autogenerated. To identify and update object it should contains `_id` property. If callback is not provided this function will be synchronous. Call variations: save(cname, |, [options] [cb]) save(cname, |, [cb]) NOTE: Field names of passed JSON objects may not contain `$` and `.` characters, error condition will be fired in this case. __Arguments__ * {String} **cname** Name of collection. * {Array|Object} jsarr Signle JSON object or array of JSON objects to save * {Function} `[cb]` Callback args: (error, {Array} of OIDs for saved objects) __Return__ * {Array} of OIDs of saved objects in synchronous mode otherwise returns {undefined}. -------------------------------------- ### load(cname, oid, cb) Loads JSON object identified by OID from the collection. If callback is not provided this function will be synchronous. __Arguments__ * {String} cname Name of collection * {String} oid Object identifier (OID) * {Function} cb Callback args: (error, obj) `obj`: Retrieved JSON object or NULL if it is not found. __Return__ * JSON object or {null} if it is not found in synchronous mode otherwise return {undefined}. -------------------------------------- ### remove(cname, oid, cb) Removes JSON object from the collection. If callback is not provided this function will be synchronous. __Arguments__ * {String} cname Name of collection * {String} oid Object identifier (OID) * {Function} cb Callback args: (error) -------------------------------------- ### find(cname, qobj, orarr, hints, cb) Execute query on collection. EJDB queries inspired by MongoDB (mongodb.org) and follows same philosophy. Supported queries: - Simple matching of String OR Number OR Array value: - {'fpath' : 'val', ...} - $not Negate operation. - {'fpath' : {'$not' : val}} //Field not equal to val - {'fpath' : {'$not' : {'$begin' : prefix}}} //Field not begins with val - $begin String starts with prefix - {'fpath' : {'$begin' : prefix}} - $gt, $gte (>, >=) and $lt, $lte for number types: - {'fpath' : {'$gt' : number}, ...} - $bt Between for number types: - {'fpath' : {'$bt' : [num1, num2]}} - $in String OR Number OR Array val matches to value in specified array: - {'fpath' : {'$in' : [val1, val2, val3]}} - $nin - Not IN - $strand String tokens OR String array val matches all tokens in specified array: - {'fpath' : {'$strand' : [val1, val2, val3]}} - $stror String tokens OR String array val matches any token in specified array: - {'fpath' : {'$stror' : [val1, val2, val3]}} - $exists Field existence matching: - {'fpath' : {'$exists' : true|false}} - $icase Case insensitive string matching: - {'fpath' : {'$icase' : 'val1'}} //icase matching Ignore case matching with '$in' operation: - {'name' : {'$icase' : {'$in' : ['tHéâtre - театр', 'heLLo WorlD']}}} For case insensitive matching you can create special type of string index. - $elemMatch The $elemMatch operator matches more than one component within an array element. - { array: { $elemMatch: { value1 : 1, value2 : { $gt: 1 } } } } Restriction: only one $elemMatch allowed in context of one array field. - $and, $or joining: - {..., $and : [subq1, subq2, ...] } - {..., $or : [subq1, subq2, ...] } Example: {z : 33, $and : [ {$or : [{a : 1}, {b : 2}]}, {$or : [{c : 5}, {d : 7}]} ] } - Queries can be used to update records: $set Field set operation. - {.., '$set' : {'field1' : val1, 'fieldN' : valN}} $upsert Atomic upsert. If matching records are found it will be '$set' operation, otherwise new record will be inserted with fields specified by argment object. - {.., '$upsert' : {'field1' : val1, 'fieldN' : valN}} $inc Increment operation. Only number types are supported. - {.., '$inc' : {'field1' : number, ..., 'field1' : number} $dropall In-place record removal operation. - {.., '$dropall' : true} $addToSet Atomically adds value to the array only if its not in the array already. If containing array is missing it will be created. - {.., '$addToSet' : {'fpath' : val1, 'fpathN' : valN, ...}} $addToSetAll Batch version if $addToSet - {.., '$addToSetAll' : {'fpath' : [array of values to add], ...}} $pull Atomically removes all occurrences of value from field, if field is an array. - {.., '$pull' : {'fpath' : val1, 'fpathN' : valN, ...}} $pullAll Batch version of $pull - {.., '$pullAll' : {'fpath' : [array of values to remove], ...}} NOTE: It is better to execute update queries with `$onlycount=true` hint flag or use the special `update()` method to avoid unnecessarily rows fetching. NOTE: Negate operations: $not and $nin not using indexes so they can be slow in comparison to other matching operations. NOTE: Only one index can be used in search query operation. NOTE: If callback is not provided this function will be synchronous. QUERY HINTS (specified by `hints` argument): - $max Maximum number in the result set - $skip Number of skipped results in the result set - $orderby Sorting order of query fields. - $onlycount true|false If `true` only count of matching records will be returned without placing records in result set. - $fields Set subset of fetched fields If a field presented in $orderby clause it will be forced to include in resulting records. Example: hints: { "$orderby" : { //ORDER BY field1 ASC, field2 DESC "field1" : 1, "field2" : -1 }, "$fields" : { //SELECT ONLY {_id, field1, field2} "field1" : 1, "field2" : 1 } } Many C API query examples can be found in `tcejdb/testejdb/t2.c` test case. To traverse selected records cursor object is used: - Cursor#next() Move cursor to the next record and returns true if next record exists. - Cursor#hasNext() Returns true if cursor can be placed to the next record. - Cursor#field(name) Retrieve value of the specified field of the current JSON object record. - Cursor#object() Retrieve whole JSON object with all fields. - Cursor#reset() Reset cursor to its initial state. - Cursor#length Read-only property: Number of records placed into cursor. - Cursor#pos Read/Write property: You can set cursor position: 0 <= pos < length - Cursor#close() Closes cursor and free cursor resources. Cursor cant be used in closed state. Call variations of find(): - find(cname, [cb]) - find(cname, qobj, [cb]) - find(cname, qobj, hints, [cb]) - find(cname, qobj, qobjarr, [cb]) - find(cname, qobj, qobjarr, hints, [cb]) __Arguments__ * {String} cname Name of collection * {Object} qobj Main JSON query object * {Array} `[orarr]` Array of additional OR query objects (joined with OR predicate). * {Object} `[hints]` JSON object with query hints. * {Function} cb Callback args: (error, cursor, count) `cursor`: Cursor object to traverse records qobj `count`: Total number of selected records __Return__ * If callback is provided returns {undefined} * If no callback and `$onlycount` hint is set returns count {Number}. * If no callback and no `$onlycount` hint returns cursor {Object}. -------------------------------------------- ### findOne(cname, qobj, orarr, hints, cb) Same as #find() but retrieves only one matching JSON object. Call variations of findOne(): findOne(cname, [cb]) findOne(cname, qobj, [cb]) findOne(cname, qobj, hints, [cb]) findOne(cname, qobj, qobjarr, [cb]) findOne(cname, qobj, qobjarr, hints, [cb]) __Arguments__ * {String} cname Name of collection * {Object} qobj Main JSON query object * {Array} `[orarr]` Array of additional OR query objects (joined with OR predicate). * {Object} `[hints]` JSON object with query hints. * {Function} cb Callback args: (error, obj) `obj` Retrieved JSON object or NULL if it is not found. __Return__ * If callback is provided returns {undefined} * If no callback is provided returns found {Object} or {null} ----------------------------------- ### update(cname, qobj, orarr, hints, cb) Convenient method to execute update queries. * `$set` Field set operation: - {some fields for selection, '$set' : {'field1' : {obj}, ..., 'field1' : {obj}}} * `$upsert` Atomic upsert. If matching records are found it will be '$set' operation, otherwise new record will be inserted with fields specified by argment object. - {.., '$upsert' : {'field1' : val1, 'fieldN' : valN}} * `$inc` Increment operation. Only number types are supported. - {some fields for selection, '$inc' : {'field1' : number, ..., 'field1' : {number}} * `$dropall` In-place record removal operation. - {some fields for selection, '$dropall' : true} * `$addToSet` | `$addToSetAll` Atomically adds value to the array only if its not in the array already. If containing array is missing it will be created. - {.., '$addToSet' : {'fpath' : val1, 'fpathN' : valN, ...}} * `$pull` | `pullAll` Atomically removes all occurrences of value from field, if field is an array. - {.., '$pull' : {'fpath' : val1, 'fpathN' : valN, ...}} Call variations of update(): update(cname, [cb]) update(cname, qobj, [cb]) update(cname, qobj, hints, [cb]) update(cname, qobj, qobjarr, [cb]) update(cname, qobj, qobjarr, hints, [cb]) __Arguments__ * {String} cname Name of collection * {Object} qobj Update JSON query object * {Array} `[orarr]` Array of additional OR query objects (joined with OR predicate). * {Object} `[hints]` JSON object with query hints. * {Function} cb Callback args: (error, count) `count` The number of updated records. __Return__ * If callback is provided returns {undefined}. * If no callback is provided returns {Number} of updated objects. ----------------------------------- ### count(cname, qobj, orarr, hints, cb) Convenient count(*) operation. Call variations of count(): count(cname, [cb]) count(cname, qobj, [cb]) count(cname, qobj, hints, [cb]) count(cname, qobj, qobjarr, [cb]) count(cname, qobj, qobjarr, hints, [cb]) __Arguments__ * {String} cname Name of collection * {Object} qobj Main JSON query object * {Array} `[orarr]` Array of additional OR query objects (joined with OR predicate). * {Object} `[hints]` JSON object with query hints. * {Function} cb Callback args: (error, count) `count`: Number of matching records. __Return__ * If callback is provided returns {undefined}. * If no callback is provided returns {Number} of matched object. ----------------------------------- ### sync(cb) Synchronize entire EJDB database with disk. __Arguments__ * {Function} cb Callback args: (error) ----------------------------------- ### dropIndexes(cname, path, cb) Drop indexes of all types for JSON field path. __Arguments__ * {String} cname Name of collection * {String} path JSON field path * {Function} `[cb]` Optional callback function. Callback args: (error) ------------------------------------ ### optimizeIndexes(cname, path, cb) Optimize indexes of all types for JSON field path. Performs B+ tree index file optimization. __Arguments__ * {String} cname Name of collection * {String} path JSON field path * {Function} `[cb]` Optional callback function. Callback args: (error) ----------------------------------- ### ensureStringIndex(cname, path, cb) ### ensureIStringIndex(cname, path, cb) ### ensureNumberIndex(cname, path, cb) ### ensureArrayIndex(cname, path, cb) Ensure index presence of String|Number|Array type for JSON field path. `IString` is the special type of String index for case insensitive matching. __Arguments__ * {String} cname Name of collection * {String} path JSON field path * {Function} `[cb]` Optional callback function. Callback args: (error) ----------------------------------- ### rebuildStringIndex(cname, path, cb) ### rebuildIStringIndex(cname, path, cb) ### rebuildNumberIndex(cname, path, cb) ### rebuildArrayIndex(cname, path, cb) Rebuild index of String|Number|Array type for JSON field path. `IString` is the special type of String index for case insensitive matching. __Arguments__ * {String} cname Name of collection * {String} path JSON field path * {Function} `[cb]` Optional callback function. Callback args: (error) ----------------------------------- ### dropStringIndex(cname, path, cb) ### dropIStringIndex(cname, path, cb) ### dropNumberIndex(cname, path, cb) ### dropArrayIndex(cname, path, cb) Drop index of String|Number|Array type for JSON field path. `IString` is the special type of String index for case insensitive matching. __Arguments__ * {String} cname Name of collection * {String} path JSON field path * {Function} `[cb]` Optional callback function. Callback args: (error) -----------------------------------