how to set value in list using linq c#

There's not a single query in LINQ that modifies the queried collection (hence "query"). Now, the only reason I added count was so that once 10000 items in a have been updated, the loop will stop, otherwise it will take a very long time to go thru all of the items. A new List, yes - but containing the same items, which will be updated correctly. Passing negative parameters to a wolframscript. Not the answer you're looking for? UPDATE This can be simplified to be listOf 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. It's exactly what I was looking for, How a top-ranked engineering school reimagined CS curriculum (Ep. 20 : 30)) I disagree, it is in fact a query, but a query with side effects. It doesn't work because Select() doesn't actually iterate through the collection until you enumerate it's results, and it requires an expression that evaluates to a value. I don't think this would help. 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. Canadian of Polish descent travel to Poland with Canadian passport. What's the cheapest way to buy out a sibling's share of our parents house if I have no cash and want to pay less than the appraised value? var list = from something in someList select GetModifiedObject (x); // but change one property private MyType Google "LINQ side effects" for more information. Web14. Did the drapes in old theatres actually say "ASBESTOS" on them? I mean, if PopulateChanges() is returning you a List<> of DateTime arrays, and you are going through all of them and setting them to DateTime.MinValue, what exactly is the code unit that you want to put in the delegate? 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. Even by limiting it like this, it still takes around 3 min. Normally I use a for loop or anonymous delegate to do it like this: LINQ is new for me. I used to use a Dictionary which is some sort of an indexed list which will give me exactly what I want when I want it. UPDATE This can be simplified to be listOf Parabolic, suborbital and ballistic trajectories all follow elliptic paths. correctionQoutas is a custom object that has four properties. You could try something like this (not a pure LINQ approach): Here is one way, assuming a class structure as follows: You can join the second list on matching IDs: I think using Join then looping through the list would be more efficient. I want to do: Just change all values for a property in all elements of my collection. foreach(var item in self) { How can I control PNP and NPN transistors together from one pin? and MatchingColumnName1 and MatchingColumnName2 are properties of collections. The list IS updated as expected. A boy can regenerate, so demons eat him for years. Which reverse polarity protection is better and why? rev2023.5.1.43405. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Find centralized, trusted content and collaborate around the technologies you use most. Which reverse polarity protection is better and why? Why don't we use the 7805 for car phone chargers? I think you try to add a complete list instead of a single CheckItems instance. What is Wario dropping at the end of Super Mario Land 2 and why? Folder's list view has different sized fonts in different folders. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. WebThis is the best I have right now: var allCountries = repository.GetCountries (); var topitem = allCountries.Single (x => x.id == 592); var finalList = new List (); finalList.Add { How do I remedy "The breakpoint will not currently be hit. LINQ is not really intended to be used for updating collections. What should I follow, if two altimeters show different altitudes? rev2023.5.1.43405. In my application I have a list of items I need to sort by price and set a rank/position index for each item. It was designed to bring native data querying to .NET. Simply put: what you're doing is, it will create new list which will replace old one, BTW the only LINQ here is. It should not be hard to analyze the complexity of this. What were the most popular text editors for MS-DOS in the 1980s? When changes are cleared, I need to reset the times to MinValue. So simply iterate over that enumeration and set the new values: Note that I cut the trailing decimals by simple arithmetic instead of converting the values to strings and back. However, one potential optimization could be realized in your foreach line as such: This would limit the set brought back to only those members that actually need their ToUpdate set rather than just setting them whether they need to or not. (from c in listOfCompany where c.id == 1 select c).First ().Name = "Whatever Name"; For Multiple updates. Asking for help, clarification, or responding to other answers. c# - how to query LIST using linq - Stack Overflow You could make it O ( n + m) (assuming only a small number of items from a match each item in b) by using a hash table. Identify blue/translucent jelly-like animal on beach. The below is practically the same as the answer provided by Florian Schmidinger: Thanks for contributing an answer to Stack Overflow! By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Which language's style guidelines should be used when writing code that is supposed to be called from another language? Connect and share knowledge within a single location that is structured and easy to search. I have my doubts that my box is 18,000 times faster than yours, so something else must be at work here. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Great answer. All I am doing is creating a working example, as my FYI says.. i'm really caling just the for loop part of it (the rest is just setup) in an area that's different from this. Be aware that it only updates the first company it found with company id 1. If you want to modify all returned objects, you still have to use a loop to iterate over the objects. Asking for help, clarification, or responding to other answers. What differentiates living as mere roommates from living in a marriage-like relationship? The only difference between them is that the .First method will throw an exception if there is no such object in the collection when the second one returns the Doing changes must be done in other logic. dont forget the return syntax it took me one hour, Very neat!

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