Referencing state from within state - React js












0















Is it possible to reference state from within state to create an id. e.g id = this.state.name + this.state.desc



Something like this?



this.state = {name:'', desc:'', id:`${this.state.name}-${this.state.desc}`}





javascript reactjs







share|improve this question




















  • 1





    What happens when you try it?

    – Herohtar
    Nov 28 '18 at 22:52











  • Depends where are you doing it. If within a class body, you will receive an error.

    – kind user
    Nov 28 '18 at 22:53











  • I think you can't since state is not yet initialized. But you will know where to get those values, so you can simply set id when your state is updated

    – soulpaul
    Nov 28 '18 at 22:54











  • i think it's possible if you're writing multiple assignments in the constructor, but i wouldn't do it. it feels like an anti-pattern, but without knowing the whole context idk what to suggest here. (this also feels more like a code review question than SE)

    – worc
    Nov 28 '18 at 23:06
















0















Is it possible to reference state from within state to create an id. e.g id = this.state.name + this.state.desc



Something like this?



this.state = {name:'', desc:'', id:`${this.state.name}-${this.state.desc}`}





javascript reactjs







share|improve this question




















  • 1





    What happens when you try it?

    – Herohtar
    Nov 28 '18 at 22:52











  • Depends where are you doing it. If within a class body, you will receive an error.

    – kind user
    Nov 28 '18 at 22:53











  • I think you can't since state is not yet initialized. But you will know where to get those values, so you can simply set id when your state is updated

    – soulpaul
    Nov 28 '18 at 22:54











  • i think it's possible if you're writing multiple assignments in the constructor, but i wouldn't do it. it feels like an anti-pattern, but without knowing the whole context idk what to suggest here. (this also feels more like a code review question than SE)

    – worc
    Nov 28 '18 at 23:06














0












0








0








Is it possible to reference state from within state to create an id. e.g id = this.state.name + this.state.desc



Something like this?



this.state = {name:'', desc:'', id:`${this.state.name}-${this.state.desc}`}





javascript reactjs







share|improve this question
















Is it possible to reference state from within state to create an id. e.g id = this.state.name + this.state.desc



Something like this?



this.state = {name:'', desc:'', id:`${this.state.name}-${this.state.desc}`}





javascript reactjs




javascript reactjs






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 29 '18 at 0:13









worc

1,58621928




1,58621928










asked Nov 28 '18 at 22:50









George BleasdaleGeorge Bleasdale

436




436








  • 1





    What happens when you try it?

    – Herohtar
    Nov 28 '18 at 22:52











  • Depends where are you doing it. If within a class body, you will receive an error.

    – kind user
    Nov 28 '18 at 22:53











  • I think you can't since state is not yet initialized. But you will know where to get those values, so you can simply set id when your state is updated

    – soulpaul
    Nov 28 '18 at 22:54











  • i think it's possible if you're writing multiple assignments in the constructor, but i wouldn't do it. it feels like an anti-pattern, but without knowing the whole context idk what to suggest here. (this also feels more like a code review question than SE)

    – worc
    Nov 28 '18 at 23:06














  • 1





    What happens when you try it?

    – Herohtar
    Nov 28 '18 at 22:52











  • Depends where are you doing it. If within a class body, you will receive an error.

    – kind user
    Nov 28 '18 at 22:53











  • I think you can't since state is not yet initialized. But you will know where to get those values, so you can simply set id when your state is updated

    – soulpaul
    Nov 28 '18 at 22:54











  • i think it's possible if you're writing multiple assignments in the constructor, but i wouldn't do it. it feels like an anti-pattern, but without knowing the whole context idk what to suggest here. (this also feels more like a code review question than SE)

    – worc
    Nov 28 '18 at 23:06








1




1





What happens when you try it?

– Herohtar
Nov 28 '18 at 22:52





What happens when you try it?

– Herohtar
Nov 28 '18 at 22:52













Depends where are you doing it. If within a class body, you will receive an error.

– kind user
Nov 28 '18 at 22:53





Depends where are you doing it. If within a class body, you will receive an error.

– kind user
Nov 28 '18 at 22:53













I think you can't since state is not yet initialized. But you will know where to get those values, so you can simply set id when your state is updated

– soulpaul
Nov 28 '18 at 22:54





I think you can't since state is not yet initialized. But you will know where to get those values, so you can simply set id when your state is updated

– soulpaul
Nov 28 '18 at 22:54













i think it's possible if you're writing multiple assignments in the constructor, but i wouldn't do it. it feels like an anti-pattern, but without knowing the whole context idk what to suggest here. (this also feels more like a code review question than SE)

– worc
Nov 28 '18 at 23:06





i think it's possible if you're writing multiple assignments in the constructor, but i wouldn't do it. it feels like an anti-pattern, but without knowing the whole context idk what to suggest here. (this also feels more like a code review question than SE)

– worc
Nov 28 '18 at 23:06












2 Answers
2






active

oldest

votes


















0














Remember you need to set the state using setState



So



this.setState({ id:`${this.state.name}-${this.state.desc}` })


This is also assuming that you have already set the state in the constructor (or somewhere else int he app).



If you are in the constructor, then this should work just fine...



this.state = { name: 'Toli', desc: 'A programmer' };

this.state = {...this.state, id:`${this.state.name}-${this.state.desc}`}


I'm assuming you want to keep name and desc in the state so I'm copying them using the spread op (...this.state)






share|improve this answer





















  • 1





    you can, and should, set state without setState in the constructor

    – worc
    Nov 28 '18 at 22:58






  • 1





    @worc - but if the OP is trying to use this.state = {....} and reference this.state inside it, then they are obviously not doing it in the constructor as the state has been previously defined.

    – Adam
    Nov 28 '18 at 23:00











  • I think that's the point. He is trying to do it in the constructor.

    – soulpaul
    Nov 28 '18 at 23:03











  • you could have multiple lines of this.state = ... and then i think you could technically do what they're asking. it wouldn't be very idiomatic though.

    – worc
    Nov 28 '18 at 23:03





















2














Nope, that won't work. this.state is initialized before the constructor, but it won't like that you are referencing an undefined portion of the object. You would need to set it after initialization. I'm assuming you would be using this.state = {blah} from your constructor. Otherwise, you should use this.setState().



However this is also bad practice because anytime you update your name or desc, it will update the state again with your new id value. I don't know the full scope of your code, but you can probably just save the id to a function that gives you the string.






share|improve this answer
























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    2 Answers
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    0














    Remember you need to set the state using setState



    So



    this.setState({ id:`${this.state.name}-${this.state.desc}` })


    This is also assuming that you have already set the state in the constructor (or somewhere else int he app).



    If you are in the constructor, then this should work just fine...



    this.state = { name: 'Toli', desc: 'A programmer' };
    
this.state = {...this.state, id:`${this.state.name}-${this.state.desc}`}


    I'm assuming you want to keep name and desc in the state so I'm copying them using the spread op (...this.state)






    share|improve this answer





















    • 1





      you can, and should, set state without setState in the constructor

      – worc
      Nov 28 '18 at 22:58






    • 1





      @worc - but if the OP is trying to use this.state = {....} and reference this.state inside it, then they are obviously not doing it in the constructor as the state has been previously defined.

      – Adam
      Nov 28 '18 at 23:00











    • I think that's the point. He is trying to do it in the constructor.

      – soulpaul
      Nov 28 '18 at 23:03











    • you could have multiple lines of this.state = ... and then i think you could technically do what they're asking. it wouldn't be very idiomatic though.

      – worc
      Nov 28 '18 at 23:03


















    0














    Remember you need to set the state using setState



    So



    this.setState({ id:`${this.state.name}-${this.state.desc}` })


    This is also assuming that you have already set the state in the constructor (or somewhere else int he app).



    If you are in the constructor, then this should work just fine...



    this.state = { name: 'Toli', desc: 'A programmer' };
    
this.state = {...this.state, id:`${this.state.name}-${this.state.desc}`}


    I'm assuming you want to keep name and desc in the state so I'm copying them using the spread op (...this.state)






    share|improve this answer





















    • 1





      you can, and should, set state without setState in the constructor

      – worc
      Nov 28 '18 at 22:58






    • 1





      @worc - but if the OP is trying to use this.state = {....} and reference this.state inside it, then they are obviously not doing it in the constructor as the state has been previously defined.

      – Adam
      Nov 28 '18 at 23:00











    • I think that's the point. He is trying to do it in the constructor.

      – soulpaul
      Nov 28 '18 at 23:03











    • you could have multiple lines of this.state = ... and then i think you could technically do what they're asking. it wouldn't be very idiomatic though.

      – worc
      Nov 28 '18 at 23:03
















    0












    0








    0







    Remember you need to set the state using setState



    So



    this.setState({ id:`${this.state.name}-${this.state.desc}` })


    This is also assuming that you have already set the state in the constructor (or somewhere else int he app).



    If you are in the constructor, then this should work just fine...



    this.state = { name: 'Toli', desc: 'A programmer' };
    
this.state = {...this.state, id:`${this.state.name}-${this.state.desc}`}


    I'm assuming you want to keep name and desc in the state so I'm copying them using the spread op (...this.state)






    share|improve this answer















    Remember you need to set the state using setState



    So



    this.setState({ id:`${this.state.name}-${this.state.desc}` })


    This is also assuming that you have already set the state in the constructor (or somewhere else int he app).



    If you are in the constructor, then this should work just fine...



    this.state = { name: 'Toli', desc: 'A programmer' };
    
this.state = {...this.state, id:`${this.state.name}-${this.state.desc}`}


    I'm assuming you want to keep name and desc in the state so I'm copying them using the spread op (...this.state)







    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited Nov 28 '18 at 23:06

























    answered Nov 28 '18 at 22:56









    ToliToli

    2,13141935




    2,13141935








    • 1





      you can, and should, set state without setState in the constructor

      – worc
      Nov 28 '18 at 22:58






    • 1





      @worc - but if the OP is trying to use this.state = {....} and reference this.state inside it, then they are obviously not doing it in the constructor as the state has been previously defined.

      – Adam
      Nov 28 '18 at 23:00











    • I think that's the point. He is trying to do it in the constructor.

      – soulpaul
      Nov 28 '18 at 23:03











    • you could have multiple lines of this.state = ... and then i think you could technically do what they're asking. it wouldn't be very idiomatic though.

      – worc
      Nov 28 '18 at 23:03
















    • 1





      you can, and should, set state without setState in the constructor

      – worc
      Nov 28 '18 at 22:58






    • 1





      @worc - but if the OP is trying to use this.state = {....} and reference this.state inside it, then they are obviously not doing it in the constructor as the state has been previously defined.

      – Adam
      Nov 28 '18 at 23:00











    • I think that's the point. He is trying to do it in the constructor.

      – soulpaul
      Nov 28 '18 at 23:03











    • you could have multiple lines of this.state = ... and then i think you could technically do what they're asking. it wouldn't be very idiomatic though.

      – worc
      Nov 28 '18 at 23:03










    1




    1





    you can, and should, set state without setState in the constructor

    – worc
    Nov 28 '18 at 22:58





    you can, and should, set state without setState in the constructor

    – worc
    Nov 28 '18 at 22:58




    1




    1





    @worc - but if the OP is trying to use this.state = {....} and reference this.state inside it, then they are obviously not doing it in the constructor as the state has been previously defined.

    – Adam
    Nov 28 '18 at 23:00





    @worc - but if the OP is trying to use this.state = {....} and reference this.state inside it, then they are obviously not doing it in the constructor as the state has been previously defined.

    – Adam
    Nov 28 '18 at 23:00













    I think that's the point. He is trying to do it in the constructor.

    – soulpaul
    Nov 28 '18 at 23:03





    I think that's the point. He is trying to do it in the constructor.

    – soulpaul
    Nov 28 '18 at 23:03













    you could have multiple lines of this.state = ... and then i think you could technically do what they're asking. it wouldn't be very idiomatic though.

    – worc
    Nov 28 '18 at 23:03







    you could have multiple lines of this.state = ... and then i think you could technically do what they're asking. it wouldn't be very idiomatic though.

    – worc
    Nov 28 '18 at 23:03















    2














    Nope, that won't work. this.state is initialized before the constructor, but it won't like that you are referencing an undefined portion of the object. You would need to set it after initialization. I'm assuming you would be using this.state = {blah} from your constructor. Otherwise, you should use this.setState().



    However this is also bad practice because anytime you update your name or desc, it will update the state again with your new id value. I don't know the full scope of your code, but you can probably just save the id to a function that gives you the string.






    share|improve this answer




























      2














      Nope, that won't work. this.state is initialized before the constructor, but it won't like that you are referencing an undefined portion of the object. You would need to set it after initialization. I'm assuming you would be using this.state = {blah} from your constructor. Otherwise, you should use this.setState().



      However this is also bad practice because anytime you update your name or desc, it will update the state again with your new id value. I don't know the full scope of your code, but you can probably just save the id to a function that gives you the string.






      share|improve this answer


























        2












        2








        2







        Nope, that won't work. this.state is initialized before the constructor, but it won't like that you are referencing an undefined portion of the object. You would need to set it after initialization. I'm assuming you would be using this.state = {blah} from your constructor. Otherwise, you should use this.setState().



        However this is also bad practice because anytime you update your name or desc, it will update the state again with your new id value. I don't know the full scope of your code, but you can probably just save the id to a function that gives you the string.






        share|improve this answer













        Nope, that won't work. this.state is initialized before the constructor, but it won't like that you are referencing an undefined portion of the object. You would need to set it after initialization. I'm assuming you would be using this.state = {blah} from your constructor. Otherwise, you should use this.setState().



        However this is also bad practice because anytime you update your name or desc, it will update the state again with your new id value. I don't know the full scope of your code, but you can probably just save the id to a function that gives you the string.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Nov 28 '18 at 23:01









        NathanNathan

        37913




        37913






























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