Find in array with different types





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I have two subClasses that will be extended to many classes. Now i will find a class with a specific type (in my case this is a property on the subClass).



After creating many instances i have a helper function that will return the first class with a match of needed type.
So far everything works fine.



My Problem
I do not get the correct ts-type when i return my class on my Helper funtion. I always get a typescript error but i have no idea how to solve that problem.



Is there anyone show me the right way to do it?
Or is there some tutorial? (I found some tutorials but only withoud extends and no dynamic store array with many different types)



My example code on the typescript playground with the ts-error










share|improve this question





























    0















    I have two subClasses that will be extended to many classes. Now i will find a class with a specific type (in my case this is a property on the subClass).



    After creating many instances i have a helper function that will return the first class with a match of needed type.
    So far everything works fine.



    My Problem
    I do not get the correct ts-type when i return my class on my Helper funtion. I always get a typescript error but i have no idea how to solve that problem.



    Is there anyone show me the right way to do it?
    Or is there some tutorial? (I found some tutorials but only withoud extends and no dynamic store array with many different types)



    My example code on the typescript playground with the ts-error










    share|improve this question

























      0












      0








      0








      I have two subClasses that will be extended to many classes. Now i will find a class with a specific type (in my case this is a property on the subClass).



      After creating many instances i have a helper function that will return the first class with a match of needed type.
      So far everything works fine.



      My Problem
      I do not get the correct ts-type when i return my class on my Helper funtion. I always get a typescript error but i have no idea how to solve that problem.



      Is there anyone show me the right way to do it?
      Or is there some tutorial? (I found some tutorials but only withoud extends and no dynamic store array with many different types)



      My example code on the typescript playground with the ts-error










      share|improve this question














      I have two subClasses that will be extended to many classes. Now i will find a class with a specific type (in my case this is a property on the subClass).



      After creating many instances i have a helper function that will return the first class with a match of needed type.
      So far everything works fine.



      My Problem
      I do not get the correct ts-type when i return my class on my Helper funtion. I always get a typescript error but i have no idea how to solve that problem.



      Is there anyone show me the right way to do it?
      Or is there some tutorial? (I found some tutorials but only withoud extends and no dynamic store array with many different types)



      My example code on the typescript playground with the ts-error







      typescript






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Nov 21 '18 at 21:52









      domreadydomready

      2246




      2246
























          1 Answer
          1






          active

          oldest

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          1














          I mentioned two things:





          1. You declared the array with type Building



            const buildingsStore: (Building) = [storehouse, barracks];




          and then in the filter expecting building to have the property type:



          return type === building.type;


          This does obviously not work, because Building does not have type.




          1. I can't sadly explain what exactly goes on in TypeScript, but removing the return type of the function and type cast the result instead works (has somethign to do with Type Inference):


          Working code here



          EDIT



          I updated my code regarding to the type property: here






          share|improve this answer
























          • Thanks, it works fine. I do not think this is the best solution but a big step to the next optimal solution.

            – domready
            Nov 22 '18 at 10:48













          • You are welcome. Type Inference isn't that bad, btw.

            – scipper
            Nov 22 '18 at 10:49












          Your Answer






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          1 Answer
          1






          active

          oldest

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          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          1














          I mentioned two things:





          1. You declared the array with type Building



            const buildingsStore: (Building) = [storehouse, barracks];




          and then in the filter expecting building to have the property type:



          return type === building.type;


          This does obviously not work, because Building does not have type.




          1. I can't sadly explain what exactly goes on in TypeScript, but removing the return type of the function and type cast the result instead works (has somethign to do with Type Inference):


          Working code here



          EDIT



          I updated my code regarding to the type property: here






          share|improve this answer
























          • Thanks, it works fine. I do not think this is the best solution but a big step to the next optimal solution.

            – domready
            Nov 22 '18 at 10:48













          • You are welcome. Type Inference isn't that bad, btw.

            – scipper
            Nov 22 '18 at 10:49
















          1














          I mentioned two things:





          1. You declared the array with type Building



            const buildingsStore: (Building) = [storehouse, barracks];




          and then in the filter expecting building to have the property type:



          return type === building.type;


          This does obviously not work, because Building does not have type.




          1. I can't sadly explain what exactly goes on in TypeScript, but removing the return type of the function and type cast the result instead works (has somethign to do with Type Inference):


          Working code here



          EDIT



          I updated my code regarding to the type property: here






          share|improve this answer
























          • Thanks, it works fine. I do not think this is the best solution but a big step to the next optimal solution.

            – domready
            Nov 22 '18 at 10:48













          • You are welcome. Type Inference isn't that bad, btw.

            – scipper
            Nov 22 '18 at 10:49














          1












          1








          1







          I mentioned two things:





          1. You declared the array with type Building



            const buildingsStore: (Building) = [storehouse, barracks];




          and then in the filter expecting building to have the property type:



          return type === building.type;


          This does obviously not work, because Building does not have type.




          1. I can't sadly explain what exactly goes on in TypeScript, but removing the return type of the function and type cast the result instead works (has somethign to do with Type Inference):


          Working code here



          EDIT



          I updated my code regarding to the type property: here






          share|improve this answer













          I mentioned two things:





          1. You declared the array with type Building



            const buildingsStore: (Building) = [storehouse, barracks];




          and then in the filter expecting building to have the property type:



          return type === building.type;


          This does obviously not work, because Building does not have type.




          1. I can't sadly explain what exactly goes on in TypeScript, but removing the return type of the function and type cast the result instead works (has somethign to do with Type Inference):


          Working code here



          EDIT



          I updated my code regarding to the type property: here







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 22 '18 at 10:01









          scipperscipper

          1,4431424




          1,4431424













          • Thanks, it works fine. I do not think this is the best solution but a big step to the next optimal solution.

            – domready
            Nov 22 '18 at 10:48













          • You are welcome. Type Inference isn't that bad, btw.

            – scipper
            Nov 22 '18 at 10:49



















          • Thanks, it works fine. I do not think this is the best solution but a big step to the next optimal solution.

            – domready
            Nov 22 '18 at 10:48













          • You are welcome. Type Inference isn't that bad, btw.

            – scipper
            Nov 22 '18 at 10:49

















          Thanks, it works fine. I do not think this is the best solution but a big step to the next optimal solution.

          – domready
          Nov 22 '18 at 10:48







          Thanks, it works fine. I do not think this is the best solution but a big step to the next optimal solution.

          – domready
          Nov 22 '18 at 10:48















          You are welcome. Type Inference isn't that bad, btw.

          – scipper
          Nov 22 '18 at 10:49





          You are welcome. Type Inference isn't that bad, btw.

          – scipper
          Nov 22 '18 at 10:49




















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