ToList ForEach in Linq

Question

I am new to Linq  I want to set two values in foreach statement like this My actual code is this foreach  Employee emp in employees        foreach Department dept in emp Departments                dept SomeProperty   null            collection AddRange emp Departments                    Little refactoring turns the above into this foreach  Employee emp in employees        emp Departments ToList   ForEach u   gt  u SomeProperty   null       collection AddRange emp Departments                    But I want something like this employees ToList   Foreach collection AddRange emp Departments   emp Departments ToList   ForEach u   gt  u SomeProperty   null

User · Answer

Try this   foreach  var dept in employees SelectMany e   gt  e Departments        dept SomeProperty   null     collection Add dept

User · Answer

employees ToList   ForEach       emp  gt                   collection AddRange emp Departments             emp Departments ToList   ForEach u  gt u SomeProperty   null

User · Answer

you want this       employees ForEach emp   gt                collection AddRange emp Departments Where dept   gt    dept SomeProperty   null  return true

User · Answer

Try with this combination of Lambda expressions   employees ToList   ForEach emp   gt         collection AddRange emp Departments       emp Departments ToList   ForEach dept   gt  dept SomeProperty   null

User · Answer

You shouldn t use ForEach in that way  Read Lippert s    foreach    vs    ForEach     If you want to be cruel with yourself  and the world   at least don t create useless List  employees All p   gt        collection AddRange p Departments       p Departments All u   gt    u SomeProperty   null  return true           return true        Note that the result of the All expression is a bool value that we are discarding  we are using it only because it  cycles  all the elements   I ll repeat  You shouldn t use ForEach to change objects  LINQ should be used in a  functional  way  you can create new objects but you can t change old objects nor you can create side-effects   And what you are writing is creating so many useless List only to gain two lines of code

User · Answer

employees ToList   Foreach u  gt    u SomeProperty   null  u OtherProperty   null        Notice that I used semicolons after each set statement that is --   u SomeProperty   null  u OtherProperty   null    I hope this will definitely solve your problem

User · Answer

You can use Array ForEach   Array ForEach employees  employee   gt       Array ForEach employee Departments  department   gt  department SomeProperty   null      Collection AddRange employee Departments

User · Answer

As xanatos said  this is a misuse of ForEach   If you are going to use linq to handle this  I would do it like this   var departments   employees SelectMany x   gt  x Departments   foreach  var item in departments        item SomeProperty   null    collection AddRange departments     However  the Loop approach is more readable and therefore more maintainable

[c#] ToList().ForEach in Linq

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