javascript - Filter IndexedDB records with multiple values -


this question has answer here:

i need able filter data indexeddb in 3 different ways.

for example, if data stored following object:

var cars = [     {type: 'econmoy',colour: 'red',agerange:'1 - 10'},     {type: 'econmoy',colour: 'blue',agerange:'11 - 20'},     {type: 'luxury',colour: 'yellow',agerange:'1 - 10'} ]

i wanted allow users filter results type, colour , agerange separately and/or jointly. hoping idbkeyrange.bound method answer doesn't work:

var lowerarray = ['econmoy','blue','1 - 10']; var upperarray = ['luxury','yellow','11 - 20']; var rangetest = idbkeyrange.bound(lowerarray,upperarray); index.opencursor(rangetest).onsuccess = ...

can suggest way of going it?

here rough fiddle of initial thoughts: http://jsfiddle.net/as55s/

any feedback appreciated.

your example seems works pretty well, unfortunately afaik, cannot filter multiple properties separately on index array.

the whole indexeddb filter processing rely on order of index keys. , compound indexe keys must seen simple concatenation of multiple values, can search using them, need respect properties order...

in example compound index order type=>colour=>agerange...

objectstore.createindex("name", ['type','colour','agerange'], { unique: false });

so can search on:

  • type
  • type and colour
  • type and colour and agerange

but can't filter separately colour , agerange in relational database. personnaly have no way here 3 possible ugly workaround:

  • execute cursor on whole object store, , filter each object in cursor loop. easiest code, , ll able more complexe filtering (startwith/endwith), ll slower, particulary huge amount of rows browse...

    (tips: can make method faster if force user fill @ last 1 specific field bind index, reduce numbre of rows filtered cursor...)

  • create compound indexe every properties order , use right 1 depending on search fields values. ll result in large amount codes , indexes objectsore, according this comment, 20 indexes single object store reasonables, support @ least 4 search field...

[edit: according comment - may misunderstood]

  • create standard index each properties , use them separately index cursor primary keys, merge results in array keeping primary keys found in every indexes query. finally, load 1 one corresponding object primary keys merged in array.

    this way pretty because don't have create , manage lot of indexes, , every fields ll support startwith filtering. loose straight cursor features, , wonder performance of loading 1 one each record js?

anyway, think indexeddb not designed such usecases. if you're planning complex search (multi-criteria queries, statistics...) relational databases (like websql) more suitable.


Comments

Post a Comment

Popular posts from this blog

commonjs - How to write a typescript definition file for a node module that exports a function? -

consider, toml node module can use: // toml.d.ts declare module toml { export function parse(value:string):any; } declare module "toml" { export = toml; } then: /// <reference path="../../../../../defs/toml/toml.d.ts"/> import toml = require('toml'); toml.parse(...); however, node module export single function, such 'glob' ( https://github.com/isaacs/node-glob ). the node usage of module be: var glob = require("glob") glob("*.js", {}, callback(err, files) { ... }); you'd naively expect this: // glob.d.ts declare function globs(paths:string, options:any, callback:{(err:any, files:string[]):void; ...but because typescripts 'import' semantics bit strange, seems can use 'import .. = require()' statement alias modules . trying call: /// <reference path="../../../../../defs/glob/glob.d.ts"/> import blog = require('glob'); results in: error ts2072: mod
Read more

openid - Okta: Failed to get authorization code through API call -

i'm integrating okta own idp server using okta's api. i'm implementing authorization code flow following steps below: in own server, use /api/v1/authn endpoint sessiontoken. use sessiontoken obtain authorization calling endpoint: /oauth2/v1/authorize?client_id=" + clientid + "&sessiontoken=" + sessiontoken + "&response_type=code&response_mode=query&scope=openid&redirect_uri=" + redirecturl + "&state=evanyang&nonce=" it's supposed return response status code 302 , location header containing redirect url code value. however, keep getting response status code 200 , without location header, html body saying "you using unsupported browser." , "javascript disabled on browser." according api documentation: http://developer.okta.com/docs/api/resources/oidc.html#authentication-request , sessiontoken parameter sufficient this: an okta one-time sessiontoken. allows api-based
Read more

thorough guide for profiling racket code -

did googling ("racket profiling", "racket measure performance"), didn't find , there no examples in docs. did google "profile" search on htdp - no luck. (profile (f ...)) output isn't obvious other small snippets. ideally want python's python -m cprofile usage examples. when search "python profiling", both duckduckgo , google give top result: 26.4. python profilers . (although scanned quickly, seems more of reference "thorough usage guide" examples. if had else in mind, perhaps please link that?) the equivalent racket documentation be: profile: statistical profiler . a usage example: #lang racket (require profile) (profile-thunk (thunk (function-to-profile arg0 arg1) )) here (thunk e) convenience (lambda () e) . bigger example: #lang racket (module mod racket (provide f) (define (f) (for/list ([i 10000]) i))) (require (prefix-in mod: 'mod)) (define (f) (for ([i 10000
Read more