javascript - React, setState warning for mounted/unmounted component -

-



i have react component using load images progressively app has been working great me. when use on page load images, though, seeing error:

warning.js:35 warning: setstate(...): can update mounted or mounting component. means called setstate() on unmounted component. no-op.

multiple times - looks once each image called. not seem effecting image components still work. wondering how rid of error though, cannot figure out how.

so here component:

import react, { proptypes } 'react';  require('./progressive-image.scss');  export default class progressiveimage extends react.component {   constructor(props) {     super(props);      this.state = {       loaded: false,       image: props.smallimg     };      this.loadimage = this.loadimage.bind(this);     this.onload = this.onload.bind(this);     this.onerror = this.onerror.bind(this);     this.image = undefined;   }    componentdidmount() {     const { largeimg } = this.props;     this.loadimage(largeimg);   }    onerror(err) {     console.warn('error loading progressive image :', err);   }    onload() {     this.setstate({       loaded: true,       image: this.image.src     });   }    componentdidupdate(nextprops) {     const { largeimg, smallimg } = nextprops;      if (largeimg !== this.props.largeimg) {       this.setstate({ loaded: false, image: smallimg }, () => {         this.loadimage(largeimg);       });     }   }     loadimage(src) {     if (this.image) {       this.image.onload = null;       this.image.onerror = null;     }      const image = new image();     this.image = image;     image.onload = this.onload;     image.onerror = this.onerror;     image.src = src;   }    render() {     const imgstyle = { 'paddingbottom': this.props.heightratio };     const { imgalt, imgtitle } = this.props;      return (       <div classname={`progressive-placeholder ${this.state.loaded ? 'loaded' : ''}`}>         {this.state.loaded &&           <img             alt={imgalt}             classname={`loaded`}             src={this.state.image}             title={imgtitle}              />         }         <img classname={`img-small ${!this.state.loaded ? 'loaded' : ''}`} src={this.state.image} alt="placeholder image loading"/>         <div style={imgstyle} ></div>       </div>     );   } }  progressiveimage.displayname = 'progressiveimage';  progressiveimage.proptypes = {   bgcolor: proptypes.string,   heightratio: proptypes.string.isrequired,   largeimg: proptypes.string.isrequired,   smallimg: proptypes.string.isrequired,   imgalt: proptypes.string,   imgtitle: proptypes.string, };

so time setstate called when onloador componentdidupdate called. thinking because called did mount , did update should not getting error. looking insight on how clean error, has me puzzled. if additional info needed, happy provide.

the problem callback in image.onload called @ any random point:

    image.onload = this.onload;

chances this.onload being called while component rendering.

the problem because this.onload called when external image resource loads when doing this.setstate, component rendering , this cause error.

to handle recommend setting loaded/image values outside of local component state , instead dispatch global state using redux.





wiki

Comments

Post a Comment

Popular posts from this blog

python - Read npy file directly from S3 StreamingBody -

-
i have many .npy (numpy) , .json files saved in s3, need download , load these files. for json files downloading files , loading dictionary using following code: obj = s3.object(bucket, key) response = obj.get() body = response['body'].read().decode('utf-8') data = json.loads(body) that way avoid writing .json file disk , reading it. now want same .npy files, equivalent? currently downloading file, saving temp file on disk , loading np.load avoid if possible. following https://stackoverflow.com/a/28196540/3509999 : obj = s3.object(bucket, key) io.bytesio(obj.get()["body"].read()) f: # rewind file f.seek(0) arr = np.load(f) wiki
Read more

python - Minimize function with Scipy minimize -

-
trying obtain d value (integer) std_diff objective function minimal, using scipy minimize. my code: def std_diff(d): return std(diff(df['bn'].values,d)); scipy.optimize import minimize b=(3,) res = minimize(std_diff,(1,), method='slsqp', bounds = b) **df['bn'].values** out[72]: array([ 2, 2, 2, 2, 3, 2, 7, 5, 7, 11, 8, 2, 11, 7, 15, 8, 7, 12, 21, 19, 32, 35, 40, 35, 21, 19, 25, 20, 40, 80, 99], dtype=int64) error is"indexerror: many indices array " in case not use bounds : res = minimize(std_diff,(1,), method='slsqp'), error: > in _minimize_slsqp(func, x0, args, jac, bounds, constraints, maxiter, > ftol, iprint, disp, eps, callback, **unknown_options) > 368 fx = float(np.asarray(func(x))) > 369 except: > --> 370 raise valueerror("objective function must return scalar") > 371 # compute constraints > 3
Read more

kotlin - Out-projected type in generic interface prohibits the use of metod with generic parameter -

-
i start using kotlin , defined interface this: interface aadapter<vh : recyclerview.viewholder> { fun oncreateaviewholder(parent: viewgroup): vh fun onbindaviewholder(v: vh, position: int) } and when try use on code: class klasa ( private val adapter: aadapter<*> ) { fun dosth(){ //... val vh = this.adapter.oncreateaviewholder(parent) //on below line error adapter.onbindaviewholder(v, position) //... } } i error out-projected type 'aadapter<*>' prohibits use of 'public abstract fun onbindaviewholder(v: t, position: int): unit i tied add "in" or "out" definition i'm confused. how allow it. replace aadapter<*> aadapter<recyclerview.viewholder> . class klasa ( private val adapter: aadapter<recyclerview.viewholder> ) { // ... because have declared aadapter has type parameter vh type subclass of recyclerview.
Read more