Multiple states sharing the same view or component in React












1















Is it possible for say two states that update a single view/component?
How do we do this in react?



this.state({

 dog: 'Canny'

 person: 'Brian'

})



<Text>{blank} likes beans.<Text>


For example, when this.state.dog updates, the field will read 'Canny likes beans', when this.state.person updates, the field will read 'Brian likes beans'. Is there a way to do this?



Edit: This is useful for the case where the view only has one window to display updates of two states, and I understand you can use a render function to achieve this, but is there a simple 'first principles' way in react to do this?






javascript reactjs react-native







share|improve this question

























  • It's unclear what you mean. Please, post valid code instead of pseudo-code, as it doesn't show the intention.

    – estus
    Nov 21 '18 at 9:31











  • @estus It's hard for me to post valid code because my question is exactly asking for the right way to do it, I will try to make the question clearer though, thanks

    – iWillGetBetter
    Nov 22 '18 at 1:32











  • This depends on expected logic behind this. In this example (it's setState, not state) both values will be updated. Which one should be shown? Should there be an error in this case?

    – estus
    Nov 22 '18 at 6:20
















1















Is it possible for say two states that update a single view/component?
How do we do this in react?



this.state({

 dog: 'Canny'

 person: 'Brian'

})



<Text>{blank} likes beans.<Text>


For example, when this.state.dog updates, the field will read 'Canny likes beans', when this.state.person updates, the field will read 'Brian likes beans'. Is there a way to do this?



Edit: This is useful for the case where the view only has one window to display updates of two states, and I understand you can use a render function to achieve this, but is there a simple 'first principles' way in react to do this?






javascript reactjs react-native







share|improve this question

























  • It's unclear what you mean. Please, post valid code instead of pseudo-code, as it doesn't show the intention.

    – estus
    Nov 21 '18 at 9:31











  • @estus It's hard for me to post valid code because my question is exactly asking for the right way to do it, I will try to make the question clearer though, thanks

    – iWillGetBetter
    Nov 22 '18 at 1:32











  • This depends on expected logic behind this. In this example (it's setState, not state) both values will be updated. Which one should be shown? Should there be an error in this case?

    – estus
    Nov 22 '18 at 6:20














1












1








1








Is it possible for say two states that update a single view/component?
How do we do this in react?



this.state({

 dog: 'Canny'

 person: 'Brian'

})



<Text>{blank} likes beans.<Text>


For example, when this.state.dog updates, the field will read 'Canny likes beans', when this.state.person updates, the field will read 'Brian likes beans'. Is there a way to do this?



Edit: This is useful for the case where the view only has one window to display updates of two states, and I understand you can use a render function to achieve this, but is there a simple 'first principles' way in react to do this?






javascript reactjs react-native







share|improve this question
















Is it possible for say two states that update a single view/component?
How do we do this in react?



this.state({

 dog: 'Canny'

 person: 'Brian'

})



<Text>{blank} likes beans.<Text>


For example, when this.state.dog updates, the field will read 'Canny likes beans', when this.state.person updates, the field will read 'Brian likes beans'. Is there a way to do this?



Edit: This is useful for the case where the view only has one window to display updates of two states, and I understand you can use a render function to achieve this, but is there a simple 'first principles' way in react to do this?






javascript reactjs react-native




javascript reactjs react-native






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 22 '18 at 1:26







iWillGetBetter

















asked Nov 21 '18 at 9:22









iWillGetBetteriWillGetBetter

5541927




5541927













  • It's unclear what you mean. Please, post valid code instead of pseudo-code, as it doesn't show the intention.

    – estus
    Nov 21 '18 at 9:31











  • @estus It's hard for me to post valid code because my question is exactly asking for the right way to do it, I will try to make the question clearer though, thanks

    – iWillGetBetter
    Nov 22 '18 at 1:32











  • This depends on expected logic behind this. In this example (it's setState, not state) both values will be updated. Which one should be shown? Should there be an error in this case?

    – estus
    Nov 22 '18 at 6:20



















  • It's unclear what you mean. Please, post valid code instead of pseudo-code, as it doesn't show the intention.

    – estus
    Nov 21 '18 at 9:31











  • @estus It's hard for me to post valid code because my question is exactly asking for the right way to do it, I will try to make the question clearer though, thanks

    – iWillGetBetter
    Nov 22 '18 at 1:32











  • This depends on expected logic behind this. In this example (it's setState, not state) both values will be updated. Which one should be shown? Should there be an error in this case?

    – estus
    Nov 22 '18 at 6:20

















It's unclear what you mean. Please, post valid code instead of pseudo-code, as it doesn't show the intention.

– estus
Nov 21 '18 at 9:31





It's unclear what you mean. Please, post valid code instead of pseudo-code, as it doesn't show the intention.

– estus
Nov 21 '18 at 9:31













@estus It's hard for me to post valid code because my question is exactly asking for the right way to do it, I will try to make the question clearer though, thanks

– iWillGetBetter
Nov 22 '18 at 1:32





@estus It's hard for me to post valid code because my question is exactly asking for the right way to do it, I will try to make the question clearer though, thanks

– iWillGetBetter
Nov 22 '18 at 1:32













This depends on expected logic behind this. In this example (it's setState, not state) both values will be updated. Which one should be shown? Should there be an error in this case?

– estus
Nov 22 '18 at 6:20





This depends on expected logic behind this. In this example (it's setState, not state) both values will be updated. Which one should be shown? Should there be an error in this case?

– estus
Nov 22 '18 at 6:20












2 Answers
2






active

oldest

votes


















2














This should be done by introducing another state property, personOrDog:



<Text>{this.state.personOrDog} likes beans.<Text>


There's no straightforward way to check previous and current person and dog state to calculate personOrDog. Previous and current states are available in shouldComponentUpdate but the use of setState to set personOrDog there is discouraged because it abuses this lifecycle hook.



This means that this issue should preferably be addressed in a place where a state is updated:



this.setState({

  dog: 'Canny',

  personOrDog: 'Canny'

});


To make code DRYer, a helper can be used to set these properties, e.g.:



const personOrDog = (key, value) => ({

  [key]: value,

  personOrDog: value

});



...



this.setState(personOrDog('dog', 'Canny'));





share|improve this answer
























  • I see, so the only way is to actually use one state to manage one datum in the view.

    – iWillGetBetter
    Nov 23 '18 at 1:24











  • There is no clean way. You cannot know which one was updated last in render function without setting this expicitly. An alternative would be to update boolean state field like isPersonUpdatedLast instead of personOrDog, so it will be used like {this.state.isPersonUpdatedLast ? this.state.person : this.state.dog}, but that's more cumbersome.

    – estus
    Nov 23 '18 at 6:45



















0














As for me, it is usual situation for React js. Whenever you change state, innerHTML of your Text component re-renders.






this.state({

 name:

 table:

})



<Text>

  Now current state.name is: {this.state.name}, current state.table: {this.state.name}

</Text>





PS: and don't forget to close tags: < / Text>






share|improve this answer
























  • Thanks for reaching out Max, using your example, it would be how can two different states update the same blank. <Text> Now current state.name/table is: {this.state.name/blank} </Text>

    – iWillGetBetter
    Nov 22 '18 at 1:23











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2 Answers
2






active

oldest

votes








2 Answers
2






active

oldest

votes









active

oldest

votes






active

oldest

votes









2














This should be done by introducing another state property, personOrDog:



<Text>{this.state.personOrDog} likes beans.<Text>


There's no straightforward way to check previous and current person and dog state to calculate personOrDog. Previous and current states are available in shouldComponentUpdate but the use of setState to set personOrDog there is discouraged because it abuses this lifecycle hook.



This means that this issue should preferably be addressed in a place where a state is updated:



this.setState({

  dog: 'Canny',

  personOrDog: 'Canny'

});


To make code DRYer, a helper can be used to set these properties, e.g.:



const personOrDog = (key, value) => ({

  [key]: value,

  personOrDog: value

});



...



this.setState(personOrDog('dog', 'Canny'));





share|improve this answer
























  • I see, so the only way is to actually use one state to manage one datum in the view.

    – iWillGetBetter
    Nov 23 '18 at 1:24











  • There is no clean way. You cannot know which one was updated last in render function without setting this expicitly. An alternative would be to update boolean state field like isPersonUpdatedLast instead of personOrDog, so it will be used like {this.state.isPersonUpdatedLast ? this.state.person : this.state.dog}, but that's more cumbersome.

    – estus
    Nov 23 '18 at 6:45
















2














This should be done by introducing another state property, personOrDog:



<Text>{this.state.personOrDog} likes beans.<Text>


There's no straightforward way to check previous and current person and dog state to calculate personOrDog. Previous and current states are available in shouldComponentUpdate but the use of setState to set personOrDog there is discouraged because it abuses this lifecycle hook.



This means that this issue should preferably be addressed in a place where a state is updated:



this.setState({

  dog: 'Canny',

  personOrDog: 'Canny'

});


To make code DRYer, a helper can be used to set these properties, e.g.:



const personOrDog = (key, value) => ({

  [key]: value,

  personOrDog: value

});



...



this.setState(personOrDog('dog', 'Canny'));





share|improve this answer
























  • I see, so the only way is to actually use one state to manage one datum in the view.

    – iWillGetBetter
    Nov 23 '18 at 1:24











  • There is no clean way. You cannot know which one was updated last in render function without setting this expicitly. An alternative would be to update boolean state field like isPersonUpdatedLast instead of personOrDog, so it will be used like {this.state.isPersonUpdatedLast ? this.state.person : this.state.dog}, but that's more cumbersome.

    – estus
    Nov 23 '18 at 6:45














2












2








2







This should be done by introducing another state property, personOrDog:



<Text>{this.state.personOrDog} likes beans.<Text>


There's no straightforward way to check previous and current person and dog state to calculate personOrDog. Previous and current states are available in shouldComponentUpdate but the use of setState to set personOrDog there is discouraged because it abuses this lifecycle hook.



This means that this issue should preferably be addressed in a place where a state is updated:



this.setState({

  dog: 'Canny',

  personOrDog: 'Canny'

});


To make code DRYer, a helper can be used to set these properties, e.g.:



const personOrDog = (key, value) => ({

  [key]: value,

  personOrDog: value

});



...



this.setState(personOrDog('dog', 'Canny'));





share|improve this answer













This should be done by introducing another state property, personOrDog:



<Text>{this.state.personOrDog} likes beans.<Text>


There's no straightforward way to check previous and current person and dog state to calculate personOrDog. Previous and current states are available in shouldComponentUpdate but the use of setState to set personOrDog there is discouraged because it abuses this lifecycle hook.



This means that this issue should preferably be addressed in a place where a state is updated:



this.setState({

  dog: 'Canny',

  personOrDog: 'Canny'

});


To make code DRYer, a helper can be used to set these properties, e.g.:



const personOrDog = (key, value) => ({

  [key]: value,

  personOrDog: value

});



...



this.setState(personOrDog('dog', 'Canny'));






share|improve this answer












share|improve this answer



share|improve this answer










answered Nov 22 '18 at 7:08









estusestus

75.2k22111228




75.2k22111228













  • I see, so the only way is to actually use one state to manage one datum in the view.

    – iWillGetBetter
    Nov 23 '18 at 1:24











  • There is no clean way. You cannot know which one was updated last in render function without setting this expicitly. An alternative would be to update boolean state field like isPersonUpdatedLast instead of personOrDog, so it will be used like {this.state.isPersonUpdatedLast ? this.state.person : this.state.dog}, but that's more cumbersome.

    – estus
    Nov 23 '18 at 6:45



















  • I see, so the only way is to actually use one state to manage one datum in the view.

    – iWillGetBetter
    Nov 23 '18 at 1:24











  • There is no clean way. You cannot know which one was updated last in render function without setting this expicitly. An alternative would be to update boolean state field like isPersonUpdatedLast instead of personOrDog, so it will be used like {this.state.isPersonUpdatedLast ? this.state.person : this.state.dog}, but that's more cumbersome.

    – estus
    Nov 23 '18 at 6:45

















I see, so the only way is to actually use one state to manage one datum in the view.

– iWillGetBetter
Nov 23 '18 at 1:24





I see, so the only way is to actually use one state to manage one datum in the view.

– iWillGetBetter
Nov 23 '18 at 1:24













There is no clean way. You cannot know which one was updated last in render function without setting this expicitly. An alternative would be to update boolean state field like isPersonUpdatedLast instead of personOrDog, so it will be used like {this.state.isPersonUpdatedLast ? this.state.person : this.state.dog}, but that's more cumbersome.

– estus
Nov 23 '18 at 6:45





There is no clean way. You cannot know which one was updated last in render function without setting this expicitly. An alternative would be to update boolean state field like isPersonUpdatedLast instead of personOrDog, so it will be used like {this.state.isPersonUpdatedLast ? this.state.person : this.state.dog}, but that's more cumbersome.

– estus
Nov 23 '18 at 6:45













0














As for me, it is usual situation for React js. Whenever you change state, innerHTML of your Text component re-renders.






this.state({

 name:

 table:

})



<Text>

  Now current state.name is: {this.state.name}, current state.table: {this.state.name}

</Text>





PS: and don't forget to close tags: < / Text>






share|improve this answer
























  • Thanks for reaching out Max, using your example, it would be how can two different states update the same blank. <Text> Now current state.name/table is: {this.state.name/blank} </Text>

    – iWillGetBetter
    Nov 22 '18 at 1:23
















0














As for me, it is usual situation for React js. Whenever you change state, innerHTML of your Text component re-renders.






this.state({

 name:

 table:

})



<Text>

  Now current state.name is: {this.state.name}, current state.table: {this.state.name}

</Text>





PS: and don't forget to close tags: < / Text>






share|improve this answer
























  • Thanks for reaching out Max, using your example, it would be how can two different states update the same blank. <Text> Now current state.name/table is: {this.state.name/blank} </Text>

    – iWillGetBetter
    Nov 22 '18 at 1:23














0












0








0







As for me, it is usual situation for React js. Whenever you change state, innerHTML of your Text component re-renders.






this.state({

 name:

 table:

})



<Text>

  Now current state.name is: {this.state.name}, current state.table: {this.state.name}

</Text>





PS: and don't forget to close tags: < / Text>






share|improve this answer













As for me, it is usual situation for React js. Whenever you change state, innerHTML of your Text component re-renders.






this.state({

 name:

 table:

})



<Text>

  Now current state.name is: {this.state.name}, current state.table: {this.state.name}

</Text>





PS: and don't forget to close tags: < / Text>






this.state({

 name:

 table:

})



<Text>

  Now current state.name is: {this.state.name}, current state.table: {this.state.name}

</Text>





this.state({

 name:

 table:

})



<Text>

  Now current state.name is: {this.state.name}, current state.table: {this.state.name}

</Text>






share|improve this answer












share|improve this answer



share|improve this answer










answered Nov 21 '18 at 9:51









Max KurtzMax Kurtz

1138




1138













  • Thanks for reaching out Max, using your example, it would be how can two different states update the same blank. <Text> Now current state.name/table is: {this.state.name/blank} </Text>

    – iWillGetBetter
    Nov 22 '18 at 1:23



















  • Thanks for reaching out Max, using your example, it would be how can two different states update the same blank. <Text> Now current state.name/table is: {this.state.name/blank} </Text>

    – iWillGetBetter
    Nov 22 '18 at 1:23

















Thanks for reaching out Max, using your example, it would be how can two different states update the same blank. <Text> Now current state.name/table is: {this.state.name/blank} </Text>

– iWillGetBetter
Nov 22 '18 at 1:23





Thanks for reaching out Max, using your example, it would be how can two different states update the same blank. <Text> Now current state.name/table is: {this.state.name/blank} </Text>

– iWillGetBetter
Nov 22 '18 at 1:23


















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