EDIT: Why waste the time on it. 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. Your first example is actually the correct method. 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. Short story about swapping bodies as a job; the person who hires the main character misuses his body. from c in listOfCompany where c.id == 1 select c => Let me try to look it up. Asking for help, clarification, or responding to other answers. If it really is a List you don't need LINQ, just use: If you are looking for the item itself, try: bool insertOrderNew = lOrders.Find(r => r == "1234") == null ? What were the most popular text editors for MS-DOS in the 1980s? How to force Unity Editor/TestRunner to run at full speed when in background? c# - conditional Updating a list using LINQ - Stack Overflow dont forget the return syntax it took me one hour, Very neat! I'm not happy yet. { I'm querying to return every element of a List, so I can then set those values. Or use (list ?? There are certainly ways to (ab)use LINQ to achieve the same results, but I'd consider them to be dirty hacks. Not the answer you're looking for? Be aware that it only updates the first company it found with company id 1. c# - Add items to list from linq var - Stack Overflow Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, How to overcome foreach loop for list object dynamically. How to set a value in one list when comparing it with other list When do you use in the accusative case? For Starship, using B9 and later, how will separation work if the Hydrualic Power Units are no longer needed for the TVC System? Use MathJax to format equations. Eric Lippert wrote a great blog post about the subject that is worth a read: "foreach" vs "ForEach". create enumerables over existing collections. A new List, yes - but containing the same items, which will be updated correctly. Boolean algebra of the lattice of subspaces of a vector space? Hm, using your example and stuffing various random data into the objects into the two lists of the sizes you specify, it executes in less than 1/100 second on my machine. There's no -1 index (not found) in my example. Learn more about Stack Overflow the company, and our products. If I understand you correctly you have to enumerate your nested array for several different reasons and would like to encapsulate that functionality to be reused.. List1 and List2 are two collections. Is there any known 80-bit collision attack? Asking for help, clarification, or responding to other answers. Connect and share knowledge within a single location that is structured and easy to search. I don't think this would help. 1. 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 What is the difference between Python's list methods append and extend? When to use .First and when to use .FirstOrDefault with LINQ? To learn more, see our tips on writing great answers. In my application I have a list of items I need to sort by price and set a rank/position index for each item. Doing changes must be done in other logic. Generic Doubly-Linked-Lists C implementation. LINQ stands for Language Integrated Query. Simple check to see if at least one object in a set has a property He also rips off an arm to use as a sword, Identify blue/translucent jelly-like animal on beach, Ubuntu won't accept my choice of password. This will help you in getting the first or default value in your Linq List search. Asking for help, clarification, or responding to other answers. I disagree, it is in fact a query, but a query with side effects. Asking for help, clarification, or responding to other answers. I just want something more concise that can be used more easily in a delegate without creating a multi-line monster. Making statements based on opinion; back them up with references or personal experience. c# - Find an item in a list by LINQ - Stack Overflow It only takes a minute to sign up. It's about querying, i.e. > var boys = new List {"Harry", "Ron", "Neville"}; > boys.IndexOf ("Neville") 2 > boys [2] == "Neville" True This will help you in getting the first or default value in your LINQ List search This search will find the first or default value, which it will return. Not the answer you're looking for? Can my creature spell be countered if I cast a split second spell after it? I want to compare these lists using LINQ and if IDs from both lists are equal, I want to set WorkingID in the first list, A list. If you want to modify all returned objects, you still have to use a loop to iterate over the objects. Write LINQ queries in C# | Microsoft Learn Find centralized, trusted content and collaborate around the technologies you use most. It's not LINQ, and it's not really much different to your nested for loops, just slightly less verbose. Which reverse polarity protection is better and why? 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( What is Wario dropping at the end of Super Mario Land 2 and why? (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. Why are players required to record the moves in World Championship Classical games? "Signpost" puzzle from Tatham's collection. Can anyone help me with a working expression? 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. 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. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? var newList = correctionQoutas.Select(x => x.Value%1 != 0 ? I use a simple list here. If x.Value has decimals, I want to change that value to take just the first decimal woithout rounding it. Why did DOS-based Windows require HIMEM.SYS to boot? What were the most popular text editors for MS-DOS in the 1980s? Why? Why don't we use the 7805 for car phone chargers? I would externalize that part into a function to make it more manageable. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Be aware that it only updates the first company it found with company id 1. I like this. Which reverse polarity protection is better and why? Also, Linq is only used here to loop over the collection, just like wudzik's answer. 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. Find centralized, trusted content and collaborate around the technologies you use most. The ToList is making a list, populating it, and the immediately discarding it. Thanks for contributing an answer to Stack Overflow! Google "LINQ side effects" for more information. Weighted sum of two random variables ranked by first order stochastic dominance. Here is an example. I don't have a C# compiler here but maybe AddRange instead of Add works: Thanks for contributing an answer to Stack Overflow! Asking for help, clarification, or responding to other answers. If you need to transform the elements, then you need to use the Select() LinQ function: This gives you an IEnumerable, to freeze the contents and actually do the evaluation, you can use the ToList() function after the Select() function. For multiple. What should I follow, if two altimeters show different altitudes? 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 think you try to add a complete list instead of a single CheckItems instance. If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? Ok, this should hopefully be of some help: I would also look into PLINQ as you have a lot of data to plow through. How can I control PNP and NPN transistors together from one pin? Using LINQ to change values in collection, How a top-ranked engineering school reimagined CS curriculum (Ep. Connect and share knowledge within a single location that is structured and easy to search. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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( What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, That's great. Set list property value using LINQ ForEach. There are a few ways (note that this is not a complete list). Could a subterranean river or aquifer generate enough continuous momentum to power a waterwheel for the purpose of producing electricity? WebIf you really want to use linq, you can do something like this li= (from tl in li select new Myclass { name = tl.name, age = (tl.name == "di" ? //d The i.age = 10 part is not different from the item.age = 10 part. LINQ: Select an object and change some properties without is there such a thing as "right to be heard"? Find centralized, trusted content and collaborate around the technologies you use most. What is the Efficiency and Performance of LINQ and Lambda Expression in .Net? I have attached my sample program. Certainly, foreach is the right way. Please read, Updating items of one List that match another List, How a top-ranked engineering school reimagined CS curriculum (Ep. 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: 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. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. I think using Join then looping through the list would be more efficient. What should I follow, if two altimeters show different altitudes? Without digging into what your actual conversion function is doing. Where can I find a clear diagram of the SPECK algorithm? You need change increment to postfix (rankPosition++) or initial value of rankPosition to 0. To learn more, see our tips on writing great answers. Is there a generic term for these trajectories? and do I need to check if _list is null in the form of from .. in _list? 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. using Linq would be: listOfCompany.Where(c=> c.id == 1).FirstOrDefault().Name = "Whatever Name"; Update all objects in a collection using LINQ, LINQ's Distinct() on a particular property, Deserializing JSON to .NET object using Newtonsoft (or LINQ to JSON maybe? Passing negative parameters to a wolframscript. LINQ Approach (Likely Unnecessary) If you absolutely had to use LINQ, you could use a Select () call to map each of your existing elements to updated versions : // Would My Planets Blue Sun Kill Earth-Life? To learn more, see our tips on writing great answers. To learn more, see our tips on writing great answers. Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. It was designed to bring native data querying to .NET. 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. Do you want the item in the list or the actual item itself (would assume the item itself). The code will look something like this. Adding EV Charger (100A) in secondary panel (100A) fed off main (200A). Since you want to change the properties of the elements in your enumeration, you should not be using linq or List.ForEach for that. Asking for help, clarification, or responding to other answers. How is this any different? You have also a way to set a default value. You can create a extension method: public static IEnumerable Do(this IEnumerable self, Action action) { 1. This article shows the three ways in which you can write a LINQ query in C#: Use query syntax. Concat all strings inside a List using LINQ, Using LINQ to remove elements from a List. It's also a violation of the expectations involved with LINQ - LINQ is about querying, which suggests there shouldn't be side effects when using LINQ, and the entire purpose here is to create side effects. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. What are the advantages of running a power tool on 240 V vs 120 V? 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 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. If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? Has the cause of a rocket failure ever been mis-identified, such that another launch failed due to the same problem? How would you do a "not in" query with LINQ? There are several different ways to accomplish but here is one using linq and one with out this would allow you to reuse this and do different things to each item. What is Wario dropping at the end of Super Mario Land 2 and why? Web3. For Starship, using B9 and later, how will separation work if the Hydrualic Power Units are no longer needed for the TVC System? With LINQ2SQL you query the database and then modify the returned objects. The list IS updated as expected. 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? When do you use in the accusative case? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Is a downhill scooter lighter than a downhill MTB with same performance? You really shouldn't use LINQ to perform side effects. Thanks for contributing an answer to Stack Overflow! Can I use my Coinbase address to receive bitcoin? How do I stop the Flickering on Mode 13h? Following the logic of the first example, we could use, msdn.microsoft.com/en-us/library/bb342451(v=vs.110).aspx, How a top-ranked engineering school reimagined CS curriculum (Ep. This new list is then discarded. c# - assign value using linq - Stack Overflow The below is practically the same as the answer provided by Florian Schmidinger: Was Aristarchus the first to propose heliocentrism? 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 //d Identify blue/translucent jelly-like animal on beach. rev2023.5.1.43405. Any suggestion? 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. This assumes that there are only 3 types of name. Does a password policy with a restriction of repeated characters increase security? Generic Doubly-Linked-Lists C implementation. Which ability is most related to insanity: Wisdom, Charisma, Constitution, or Intelligence? Find centralized, trusted content and collaborate around the technologies you use most. Should I re-do this cinched PEX connection? If we had a video livestream of a clock being sent to Mars, what would we see? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. How can I control PNP and NPN transistors together from one pin? my code gives error can you please tell how i do this. Reme. rev2023.5.1.43405. So any LINQ way to search like "from .. in where select", Nah, sorry. Adding EV Charger (100A) in secondary panel (100A) fed off main (200A). "Signpost" puzzle from Tatham's collection. Has the Melford Hall manuscript poem "Whoso terms love a fire" been attributed to any poetDonne, Roe, or other? Is there any known 80-bit collision attack? rev2023.5.1.43405. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. If you want the index of the element, this will do it: You can't get rid of the lambda in the first pass. I really don't understand why you say it's not meant for this. I think your code is perfectly readable and won't improve much if you force it to have lots of lambdas and such. (Your question does not sound like you want to copy the original objects). It's an easy way to filter out nulls. The following example depicts the behavior of the Enumerable.Distinctmethod on a Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. rev2023.5.1.43405. Did the drapes in old theatres actually say "ASBESTOS" on them? Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? How do I remedy "The breakpoint will not currently be hit. Linq expression to set all values of an array to a given value Even by limiting it like this, it still takes around 3 min. WebYou can try LINQ. Where does the version of Hamapil that is different from the Gemara come from? 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 Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. What differentiates living as mere roommates from living in a marriage-like relationship? // 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. Thanks for contributing an answer to Stack Overflow! Web14. When new changes occure, then those elements get a new DateTime. Connect and share knowledge within a single location that is structured and easy to search. Find centralized, trusted content and collaborate around the technologies you use most. Why did DOS-based Windows require HIMEM.SYS to boot? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Since you haven't given any indication to what you want, here is a link to 101 LINQ samples that use all the different LINQ methods: 101 LINQ Samples. 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. Can you use lambda expressions and .find? What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? Why don't we use the 7805 for car phone chargers? UPDATE This can be simplified to be listOf By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Can my creature spell be countered if I cast a split second spell after it? Could a subterranean river or aquifer generate enough continuous momentum to power a waterwheel for the purpose of producing electricity? Can you perhaps include some description of your answer instead of just posting a blob of code? You can't modify a collection while you're iterating it.