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. Here is one way to rewrite your method to use LINQ: You can use FirstOfDefault with the Where LINQ extension to get a MessageAction class from the IEnumerable. Which reverse polarity protection is better and why? C# Set field of all items in list to same value - Stack Overflow Note that you can add a ForEach extension method which performs an action on each object, but I would still recommend avoiding that. How do I stop the Flickering on Mode 13h? Can these methods be used with other collections too like, @yellavon these are extension methods on any type that implements. In both cases , the update is not done with Linq :). What is the difference between Python's list methods append and extend? For multiple. I like this. I am using below linq query to set value of SecKey, but I still see the old value in list studentData, below id the sample I am It's about querying, i.e. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Eric Lippert wrote a great blog post about the subject that is worth a read: "foreach" vs "ForEach". You should iterate your list, and modify your values like: foreach (var student in myList) { if (student.Name == "Tom") { student.Marks = 35; } } Or foreach (var student Use LINQ to get items in one List<>, that are not in another List<>. Can I use the spell Immovable Object to create a castle which floats above the clouds? When to use .First and when to use .FirstOrDefault with LINQ? How can I control PNP and NPN transistors together from one pin? Connect and share knowledge within a single location that is structured and easy to search. ), Ubuntu won't accept my choice of password. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Asking for help, clarification, or responding to other answers. While you can use a ForEach extension method, if you want to use just the framework you can do collection.Select (c => {c.PropertyToSet = value; return Making statements based on opinion; back them up with references or personal experience. Why is it shorter than a normal address? Making statements based on opinion; back them up with references or personal experience. I think you try to add a complete list instead of a single CheckItems instance. c# - Add items to list from linq var - Stack Overflow 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? Making statements based on opinion; back them up with references or personal experience. You can select multiple fields using linq Select as shown above in various examples this will return as an Anonymous Type. And the enumerable containing the objects isn't modified at all. rev2023.5.1.43405. You have also a way to set a default value. Could a subterranean river or aquifer generate enough continuous momentum to power a waterwheel for the purpose of producing electricity? For Starship, using B9 and later, how will separation work if the Hydrualic Power Units are no longer needed for the TVC System? Which was the first Sci-Fi story to predict obnoxious "robo calls"? User without create permission can create a custom object from Managed package using Custom Rest API. A boy can regenerate, so demons eat him for years. What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? Be aware that it only updates the first company it found with company id 1. For multiple (from c in listOfCompany where c.id == 1 select c).First( I pass a List a using ref, along with another List b. I need to cycle thru List b, which contains around 200,000 items, and for each item in b, it it matches criteria in a, which contains 100,000 or more items, and update it. UPDATE This can be simplified to be listOf But then, at this point, you're better off (with less typing) doing it the "clear" way: This is shorter, very clear in its intent, and very clean. Asking for help, clarification, or responding to other answers. Which language's style guidelines should be used when writing code that is supposed to be called from another language? What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, Sometimes when modifying properties in a foreach loop, the changes do not remain. I want to do: Just change all values for a property in all elements of my collection. So, finally, I have found an 'inermediate' solution, the 'foreach' method, just similar to the 'Select': Anyway may be it's not as clear as the more simple: First off, this is not a good idea. Where does the version of Hamapil that is different from the Gemara come from? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? Why are players required to record the moves in World Championship Classical games? Can I use my Coinbase address to receive bitcoin? Any suggestion? Interpreting non-statistically significant results: Do we have "no evidence" or "insufficient evidence" to reject the null? When do you use in the accusative case? What is the symbol (which looks similar to an equals sign) called? Ubuntu won't accept my choice of password. Concat all strings inside a List using LINQ, Using LINQ to remove elements from a List. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, No offense, but this seems like using Linq for the sole purpose of using linq, not because it's actually solving a problem (as a matter of fact, it's created a problem), I may be wrong, but I thought there is no, How a top-ranked engineering school reimagined CS curriculum (Ep. What is this brick with a round back and a stud on the side used for? This should work Of course you can write your own ForEach extension for IEnumerable but I remember I had side-effect with it. The following example depicts the behavior of the Enumerable.Distinctmethod on a If you want to create a new List with each element set to a value, you can do this: var changes = Enumerable.Range (0, width) .Select (x => 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 Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, This question is difficult/dangerous to answer without misleading people into thinking that LINQ is an appropriate solution to your problem. Not the answer you're looking for? Weighted sum of two random variables ranked by first order stochastic dominance. If we had a video livestream of a clock being sent to Mars, what would we see? What is Wario dropping at the end of Super Mario Land 2 and why? is there such a thing as "right to be heard"? "Signpost" puzzle from Tatham's collection. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Why don't we use the 7805 for car phone chargers? 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. If we had a video livestream of a clock being sent to Mars, what would we see? Generating points along line with specifying the origin of point generation in QGIS. create enumerables over existing collections. Weighted sum of two random variables ranked by first order stochastic dominance. Doing changes must be done in other logic. If it is possible, how? If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? I don't have a C# compiler here but maybe AddRange instead of Add works: To learn more, see our tips on writing great answers. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Use MathJax to format equations. Why does Acts not mention the deaths of Peter and Paul? my code gives error can you please tell how i do this. According to this link: Update all objects in a collection using LINQ, you can do this: repo.getAll().Select(c => {c.B = value; return c;}).ToList(); However, By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. I don't have a C# compiler here but maybe AddRange instead of Add works: Thanks for contributing an answer to Stack Overflow! Not the answer you're looking for? Simply put: what you're doing is, it will create new list which will replace old one, BTW the only LINQ here is. Great answer. Even if there is a solution out there, I'm not sure I'd use Linq for something like this. If you want to avoid this anonymous type here is the int index = mylist.FindIndex (p => p.id == 1); if (index<0) { mylist.Add (car3); } else { mylist [index] = car3; } This just uses the existing FindIndex to Reme. Unexpected uint64 behaviour 0xFFFF'FFFF'FFFF'FFFF - 1 = 0? Can you use lambda expressions and .find? List Assigning a value to a parameter of an lambda does not change the queried collection Linq expression to set all values of an array to a given value, How a top-ranked engineering school reimagined CS curriculum (Ep. Adding EV Charger (100A) in secondary panel (100A) fed off main (200A), Folder's list view has different sized fonts in different folders. Has the cause of a rocket failure ever been mis-identified, such that another launch failed due to the same problem? Making statements based on opinion; back them up with references or personal experience. rev2023.5.1.43405. 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. This article shows the three ways in which you can write a LINQ query in C#: Use query syntax. Use method syntax. Use a combination of query syntax and method syntax. The following examples demonstrate some simple LINQ queries by using each approach listed previously. Making statements based on opinion; back them up with references or personal experience. Two points. I have a list where i whant to change the value of a double property in that list if that property has decimals. Your first example is actually the correct method. Where does the version of Hamapil that is different from the Gemara come from? Why did US v. Assange skip the court of appeal? c# - ToList method in Linq - Stack Overflow I'm not happy yet. How do I get the number of elements in a list (length of a list) in Python? Very useful. is there such a thing as "right to be heard"? The list IS updated as expected. Could a subterranean river or aquifer generate enough continuous momentum to power a waterwheel for the purpose of producing electricity? Making statements based on opinion; back them up with references or personal experience. This will help you in getting the first or default value in your Linq List search. Find centralized, trusted content and collaborate around the technologies you use most. It should not be hard to analyze the complexity of this. Where will return all items which match your criteria, so you may get an IEnumerable with one element: First will return the first item which matches your criteria: Note that FirstOrDefault() will behave the same, except it will return null for reference types, or the default value for value types, instead of throwing an exception. Which method performs better: .Any() vs .Count() > 0? 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. I found SingleOrDefault to be my answer of choice - same as Single but returns 'null' if it can't find it. Short story about swapping bodies as a job; the person who hires the main character misuses his body. correctionQoutas is a custom object that has four properties. Identify blue/translucent jelly-like animal on beach. However, those are all lamda expression style. Why waste the time on it. What you could do, if you don't want to do it the first way and if your collection is a list already (but not an IEnumerable) you can use the ForEach extension method in linq to do what you're asking. 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? how to check for a value in a list of decimal C#, C# Select From Json List Using Where Clause, String search function XML file with ASP.NET MVC. //using linq list = Students.Where (s => s.Name == "ABC").ToList (); //traditional way foreach (var student in Students) { if (student.Name == "ABC") list.Add If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? Whenever I wish to access my margins values, for instance, I address my dictionary: So, depending on what you're doing, a dictionary can be useful. foreach(var item in self) { What are the advantages of running a power tool on 240 V vs 120 V? I need to store the rank because the price may change Not the answer you're looking for? It's an easy way to filter out nulls. 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. Not the answer you're looking for? 1. Is there any known 80-bit collision attack? 20 : 30)) This assumes that there are only 3 types of name. Linq expression to set all values of an array to a given value x.Value = Convert.ToDouble(string.Format("{0:0.0}", x)) : x.Value = x.Value); This gives you an Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? It's better to operate on List. Is there any known 80-bit collision attack? // Next, when I try to add vnlist to vendlist, I get an error as I cannot add this to the list I get and error saying I have some invalid arguments. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. How are engines numbered on Starship and Super Heavy? What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? What is Wario dropping at the end of Super Mario Land 2 and why? To learn more, see our tips on writing great answers. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Thanks for contributing an answer to Stack Overflow! rev2023.5.1.43405. this would be used for thing done to each date time as opposed to thing done with each date time That would be slightly different. When to use .First and when to use .FirstOrDefault with LINQ? If you had a more generic collection IEnumerable, you can use Select in Linq to build a projection where property will be set as desired (original collection will be left untouched!): listOfRequestAssigned .Where (x => x.RequestedNumber == CurrentRequest) .Select (x => { x.RequestCompleted = true; return x; }) Which reverse polarity protection is better and why? 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? I would externalize that part into a function to make it more manageable. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Double StartTime, Double EndTime, Double Value and string Id. That's all it does. Thanks for contributing an answer to Stack Overflow! When new changes occure, then those elements get a new DateTime. I disagree, it is in fact a query, but a query with side effects. Should I re-do this cinched PEX connection? Single will return a single result, but will throw an exception if it finds none or more than one (which may or may not be what you want): Note that SingleOrDefault() will behave the same, except it will return null for reference types, or the default value for value types, instead of throwing an exception. This search will find the first or default value, which it will return. How to call asynchronous method from synchronous method in C#? As sircodesalot mentioned, you can't use linq to do something like that. LINQ is not really intended to be used for updating collections. There are a few ways (note that this is not a complete list). c# - Change value in List using Linq - Stack Overflow Also, Linq is only used here to loop over the collection, just like wudzik's answer. Is there any known 80-bit collision attack? This appears to be a response to another answer rather than an answer to the question. The best answers are voted up and rise to the top, Not the answer you're looking for? Avoiding it would require enumerating the collection: Again, I wouldn't recommend this. How do I remedy "The breakpoint will not currently be hit. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. If you really want to use linq, you can do something like this. Asking for help, clarification, or responding to other answers. Thanks for contributing an answer to Code Review Stack Exchange! Connect and share knowledge within a single location that is structured and easy to search. If we need to find an element from the list, then we can use the Find and FindAll extensions method, but there is a slight difference between them. Thanks. AddRange takes an enumerable, and it will enumerate it all on its own. How a top-ranked engineering school reimagined CS curriculum (Ep. When do you use in the accusative case? WebYou can try LINQ. What were the most popular text editors for MS-DOS in the 1980s? Extract values from HttpContext.User.Claims, Ultrawingrid - Select row based on unique value, Concat all strings inside a List using LINQ, Using LINQ to remove elements from a List. See below for arguments against it. If you make your expression return a value, and add something that will fully evaluate the query, such as ToList(), to the end, then it will "work", ie: That being said, ToList() has some disadvantages - mainly, it's doing a lot of extra work (to create a List) that's not needed, which adds a large cost. You can't modify a collection while you're iterating it.