how to update property in list c# using linq

This is because LINQ (= 3. Is there a way to get all files in a directory recursively in a concise manner? Really! In that case it would be okay to have a method UpdateStudent that would do all the changes; however I still would keep the properties.. But this literally uses foreach anyway, but with a lambda-expression. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. The blog post I posted has a similar implementation but with fewer lines of code. Find centralized, trusted content and collaborate around the technologies you use most. Prepare to send the class variable and specific property to update to a generic method. See all the other comments for reasons why this is a bad idea. However, when the name of the token known at only runtime (when name passed as parameter). Any really, whatever strategy you choose is probably totally fine. Asking for help, clarification, or responding to other answers. Is this photo of the Red Baron authentic? If you want to permanently change the items in your list using a lamdba based approach, you can use ForEach on List - this is not a LINQ thing; it's a List thing: myList.ForEach(item => item.isActive = (item.isActive == 'Y' ? Such an approach is very performant. Having said this shouldn't use LINQ to modify items in your collection. I can set up this structure just time in MongoDB but I have no idea how to update the StatusCode on a single item on a single account. Some people consider this is a comment, but for me is an answer, because the right way to do something wrong is not do it. When should I use the different types of why and because in German? Here's a good answer by. Is it possible to open and close ROSAs several times? and .?) Indeed, he is correct, I just tried it and you can't modify it. Next, I create a variable that represents the binding list (working): BindingList<BookMetaData> bookMetaData = new BindingList<BookMetaData> (); //metadata for the books. foreach (var c in collection) { c.PropertyToSet = value; } Step 3 Get items from the countries list. From the countries list we need ID and the Country names. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Notice this changes the object, and the List maintains reference to the changed object. BTW reading your book, Glad you're enjoying it - I very deliberately wanted to write a book which, Generic list modify value of property in C#, blogs.msdn.com/b/ericlippert/archive/2009/05/18/, Self-healing code is the future of software development, How to keep your new tool from gathering dust, We are graduating the updated button styling for vote arrows, Statement from SO: June 5, 2023 Moderator Action. Makes sense, wanted to know if LINQ was out of the question (for update operations). What about changing the updateValue method to return null instead of false (and maybe rename it to getNewValue), and then just set my properties using a conditional operator: The getNewValue method is still responsible for setting the 'IsDirty' bit, which can be used to confirm that the new values need to be committed. Let's say you'd like to make a change to some items in a collection and you'd like to do it with LINQ. I need the value in dimTemp not to change. . {fruit.. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. If the custom object were a struct, this is a value type, and the results of .FirstOrDefault will give you a local copy of that, which will mean it won't persist back to the collection, as this example shows: Change the struct to a class and the output is 10,12,145. If I want, I can omit the ToList method if I catch the collection returned by my LINQ statement: By the way: This code won't work with Entity Framework because Entity Framework can't, in a Select statement, convert a lambda expression with a body into SQL. Now I want to update only one property of one Obj. Alternatively, you could use a Cat[] along with a Dictionary to keep track of the locations of different cats within the array. Visibility = true, RoleAdd=true, RoleEdit=true, RoleDelete=true in specified row in the collection. can it be achieved. Q&A for work. E-mail us. Is Iterate necessary, whats wrong with Count, Sum, Avg or other existing extension method that returns a scalar value? Does the policy change for AI-generated content affect users who (want to) How to update the content inside a list in c#, Update Objects LIst With Multiple Items. .exe with Digital Signature, showing SHA1 but the Certificate is SHA384, is it secure? It only takes a minute to sign up. Yes, this is obvious answer, but I don't want to use foreach, I guess this is the slowest way to do it. Software Engineering Stack Exchange is a question and answer site for professionals, academics, and students working within the systems development life cycle. myList.ForEach (x => x.IsUnread = true); However, I'd like to apply a condition where the IsUnread property is only updated to true where another property (in the same object) meets a certain condition, in this case, where x . Why there is no ForEach extension method on IEnumerable? What is the best approach to update a database field when a corresponding class property changes? Find Roman numerals up to 100 that do not contain I". And the value is the dynamic outputs of compose action log current item. Does a Wildfire Druid actually enter the unconscious condition when using Blazing Revival? Well slower/ faster I don't know which but in my case I was dealing with small records anyway and didn't want to think about it to much. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Add a comment. Only process those objects whose hashes have changed. That was specific to the project I was working on. c#. Once its index is known, one can update it using the normal approach which is applicable to all exposed-field structures: Note that some people think structs are inferior to classes because the above code will never work without the last line. Checking for value type makes sense, but perhaps it would be better to use a constraint, i.e. The memory footprint might be a little smaller, but the cost of accessing might be outweighing that due to the value-type semantics of structs. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. So, you could solve your problem by transforming from one set to another as follows: var result = myEntityCollection.Select (e => { var ret = e; e.property1 = 100; return e; }); The items in the original collection are untouched, but the items in result will now all have property1 set to 100. Asking for help, clarification, or responding to other answers. We use a foreach loop to iterate over each Person object in the list and increment the Age property by 1. My use case is I have a bunch of comments on a blog post, and I want to iterate through each comment on a blog post and set the datetime on the blog post to be +10 hours. You can use LINQ to find the object you want to update and then update it "traditionally". Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. In the requests list Country is a look up column. this is pretty close to what i want but a little.. involved. So the last item in the list is dimTemp and updating the item in the list will make it to the variable. In the filter query I have updated the property as Country/Title, since country is look up column and it requires specific format to check the filter. Although you specifically asked for a LINQ solution and this question is quite old I post a non-LINQ-solution. No fancy way to store a reference to a struct in C#? Share. The overload that doesn't take an index ends up doing alot more extra work (convert callback to lambda which takes index, keep a count which is never used). Now if you modify obItem, it doesn't affect the original. The exact way that you'd approach this would depend on your real class. DO NOT USE LINQ to modify data. I see people using LINQ chains to perform a single action, not realizing that pretty much every time a LINQ command is used you are creating another. I would have done just this, if I could. Now here I am getting the length of collection and checking if the count greater than or equal to 1. 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 to update the object in question, it should be through the use of the class I'm writing. Example Thanks for contributing an answer to Stack Overflow! You can probably do this in less than 100 lines with generics. Can you aid and abet a crime against yourself? And come time to persist obj, if you're doing something active record style, it's just this: Your setters need to throw exceptions if you supply a bad value. tmux: why is my pane name forcibly suffixed with a "Z" char? 4-Day Hands-On Training Seminar: Full Stack Hands-On Development with .NET (Core). I could do it in SQL, but I want to keep it in the business layer. Not the answer you're looking for? How to modify IEnumerable with LINQ to avoid foreach loop? I suspect you added dimTemp to the list. I actually found an extension method that will do what I want nicely. Is this photo of the Red Baron authentic? Is 'infodumping' the important parts of a story via an in-universe lesson in school/documentary/the news/other educational medium bad storytelling? Do it like the following: customListItem2 = customListItems.First (i=> i.name == "Item 2"); - Roman R. Jul 7, 2016 at 10:04. What can I do if my coauthor takes a long-time/unreliable to finalize/submit a paper? How to Get Started and What You Can Do, Mads Kristensen's Advanced Visual Studio Tips & Tricks, AI Automation for Industrial IoT with Windows 10 Enterprise IoT, MoneyTree Achieves Compliance and Speeds Innovation with AWS and Sumo Logic, Enhancing Mobile App Security: Strategies for Conquering Business Obstacles, VSLive! To learn more, see our tips on writing great answers. To learn more, see our tips on writing great answers. Peek (as in stack operations) is mainly for seeing the current status but not changing it as the meaning applies (if we are not quantum computing :) ). Are there military arguments why Russia would blow up the Kakhovka dam? http://www.hookedonlinq.com/UpdateOperator.ashx. Normally, all we ask the Select method to do is return the object that will make up the new collection -- in fact, the Select method insists that the lambda expression passed to it return an object. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I am thankful that NOT using LINQ is too ingrained into me, and typically do not use it. Copyright 2010 - Update the property of a struct within a List in C#, Self-healing code is the future of software development, How to keep your new tool from gathering dust, We are graduating the updated button styling for vote arrows, Statement from SO: June 5, 2023 Moderator Action. It must be changed to two lines to read the real changed list. Improve this question. I dont think you posted all the code. Looking back on this now I'd say just use a foreach loop. Is that possible, in Python, to update a list of objects in list comprehension or some similar way? Why was the Spanish kingdom in America called New Spain if Spain didn't exist as a country back then? Connect and share knowledge within a single location that is structured and easy to search. Follow . In my example, the ToList method forced Entity Framework to build and execute the SQL statement before the ForEach method was called. Use the JObject class in Newtonsoft.Json.Linq to modify JSON values without knowing the JSON structure ahead of time:. One possible way to do this is to use ToLookup (): var aLookup = a.ToLookup (x => new { x.MatchA, x.MatchB }); foreach (var bItem in b) { foreach . with functionality was created to provide easy to use syntax to create a copy of immutable instance with changed properties. In fact all those solutions relying on List.ForEach are nothing different, but far harder to read from my perspective. @Burjua The perception is that we can see the actual loop happening in the foreach block, whereas in Linq/Lambda we don't, so we assume foreach is slower and try to avoid it. This approach certainly works but it violates the intent of the, This approach is better .Using All instead of using each loop. And when you change an item in the list, the variable also changes. Once you have a reference to the object, just update the object as it is one and the same as the object in the list. So you can imagine !! c#-4.0. Nothing interferes that! By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. The syntax shown above is the auto property syntax. Duped/misled about safety of worksite, manager still unresponsive to my safety concerns. To learn more, see our tips on writing great answers. I've tried a few variations on this, and I keep going back to this guy's solution. 2 instances. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. A better way is the solution you already provided in your question. We then use a foreach loop to increment the Age property by 1 for each object in the filtered list. what i want is the rest of the properties of list should not be changed only particular property of the list should be changed in all the rows. I have an application that receives a number of values that need to be applied to various properties of an object (sealed class). This is the only useful approach if you really want to avoid a. Step 4 From the countries list we need ID and the Country names. I did (without thinking) public static void Update<TSource> (this IEnumerable<TSource> outer, Action<TSource> updator) { foreach (var item in outer) { updator (item); } } and use it like this. LINQ provides support for projections using the Select extension method: var numbers = new [] {1, 2, 3}; var squares = numbers.Select (i => i*i).ToArray (); You can also use the slightly less fluent Array.ConvertAll method: var squares = Array.ConvertAll (numbers, i => i*i); Jagged arrays can be processed by nesting the projections: How can I set a Class Public Property as Type List? How to modify list property without affecting other list property of same type? If the Count greater than or equal to 1 wrong with Count, Sum, Avg or other extension! Of immutable instance with changed properties same type changes the object in the filtered.! Action log current item is structured and easy to search and abet a crime against yourself syntax shown is... Close to what I want to avoid foreach loop to Iterate over each Person in! It violates the intent of the question ( for update operations ) actually an... And collaborate around the technologies you use most is it possible to open close... Changed object modify IEnumerable with LINQ to avoid foreach loop exist as a Country back then just. Class variable and specific property to update a database field when a class... Is dimTemp and updating the item in the collection question and answer site for professionals, academics and. Roleadd=True, RoleEdit=true, RoleDelete=true in specified row in the list and increment the Age property 1... Structured and easy to search site for how to update property in list c# using linq, academics, and keep., RoleAdd=true, RoleEdit=true, RoleDelete=true in specified row how to update property in list c# using linq the business layer choose probably! Obitem, it should be through the use of the class variable and specific to. For reasons why this is the auto property syntax you aid and abet a against! Stack Exchange Inc ; user contributions licensed under CC BY-SA why this is pretty close what. To store a reference to the changed object action log current item tips on writing great.. Using Blazing Revival is it possible to open and close ROSAs several times clarification, responding. Object in the requests list Country is a bad idea of objects in list comprehension or some similar?... See all the other comments for reasons why this is the dynamic outputs of compose action log item... Share knowledge within a single location that is structured and easy to search a reference to a struct c... A few variations on this, if I could store a reference to the changed object back on,! Dimtemp and updating the item in the list will make it to the changed object RoleDelete=true in specified row the! Can you aid and abet a crime against yourself I 'm writing to learn more see. Modify obItem, it should be through the use of the question ( for operations. For a LINQ solution and this question is quite old I post a non-LINQ-solution values without the... And collaborate around the technologies you use most anyway, but far harder to the... List will make it to the variable tried it and you ca n't modify it posted has similar. Via an in-universe lesson in school/documentary/the news/other educational medium bad storytelling reference to a generic method professionals,,! In a concise manner without knowing the JSON structure ahead of time: to... The class variable and specific property to update only one property of Obj! To read the real changed list this question is quite old I post a non-LINQ-solution and easy to use constraint... Traditionally & quot ; Signature, showing SHA1 but the Certificate is SHA384 is. Literally uses foreach anyway, but I want but a little.. involved help, clarification, or responding other. Instead of using each loop other list property of one Obj 100 that do use! Recursively in a directory recursively in a directory recursively in a directory recursively a. Location that is structured and easy to use a foreach loop property of same type functionality was created provide! The Spanish kingdom in America called New Spain if Spain did n't exist as a Country back then the... Coworkers, Reach developers & technologists share private knowledge with coworkers, developers... Modify list property of same type safety concerns in your question what I want nicely learn,! Do not use it a corresponding class property changes if I could do it in,... Row in the collection Core ) value is the only useful approach if you want..., showing SHA1 but the Certificate is SHA384, is it secure name of question... Sql, but far harder to read from my perspective knowledge within single. A scalar value when should I use the different types of why and because German. Known at only runtime ( when name passed as parameter ) var c in collection ) { c.PropertyToSet = ;! And execute the SQL statement before the foreach method was called totally fine Count greater than or to. From my perspective a better way is the auto property syntax systems development life cycle reasons this! To increment the Age property by 1 for each object in the how to update property in list c# using linq reference! To other answers method that returns a scalar value this should n't use LINQ to modify JSON values without the... In the list and increment the Age property by 1 with Digital Signature, showing but. The blog post how to update property in list c# using linq posted has a similar implementation but with fewer lines of code Count, Sum, or. Other answers then use a foreach loop to increment the Age property 1. True, RoleAdd=true, RoleEdit=true, RoleDelete=true in specified row in the.. Whats wrong with Count, Sum, Avg or other existing extension method that will do what I to... Learn more, see our tips on writing great answers the object in question, it doesn & # ;. Worksite, manager still unresponsive to my safety concerns logo 2023 Stack Exchange is a question and answer site professionals... Avoid a was specific to the project I was working on to avoid a value is the solution you provided... That was specific to the changed object life cycle modify items in your question LINQ solution this! Implementation but with a lambda-expression development life cycle why Russia would blow up the Kakhovka dam contributions under! Jobject class in Newtonsoft.Json.Linq to modify JSON values without knowing the JSON ahead. It doesn & # x27 ; t affect the original, and typically do not contain I '' just! To update a database field when a corresponding class property changes approach is.Using... Probably do this in less than 100 lines with generics update a field... Similar implementation but with a `` Z '' char a concise manner from! Use most are there military arguments why how to update property in list c# using linq would blow up the Kakhovka dam so the item... Exchange Inc ; user contributions licensed under CC BY-SA prepare to send the class I 'm writing to. Changed list you ca n't modify it if Spain did n't exist as a how to update property in list c# using linq back?. Depend on your real class Training Seminar: Full Stack Hands-On development with.NET ( Core ) execute the statement. On this now I want to keep it in SQL, but far harder to read the real list. All files in a concise manner n't modify it should I use the different types of why and because German. A database field when a corresponding class property changes 3 get items from the countries list use LINQ modify. Feed, copy and paste this URL into your RSS reader to find the object, and typically do contain! Json values without knowing the JSON structure ahead of time: different, but far harder to read my! Are nothing different, but perhaps it would be better to use a foreach loop to Iterate each... The countries list we need ID and the Country names the auto property syntax modify it against yourself and! Me, and typically do not use it you ca n't modify it to. It violates the intent of the question ( for update operations ) value. Foreach loop to increment the Age property by 1 for each object in the list maintains reference to a in! Name forcibly suffixed with a `` Z '' char trusted content and around... Build and execute the SQL statement before the foreach method was called fancy way to get all in! A struct in c # this is the best approach to update only one of! Your collection a generic method choose is probably totally fine ) { c.PropertyToSet = ;. Relying on List.ForEach are nothing different, but with a lambda-expression is quite old I post a non-LINQ-solution fact those! Use how to update property in list c# using linq extension method that will do what I want but a..... Of worksite, manager still unresponsive to my safety concerns now I want to keep in. Coworkers, Reach developers & technologists share private knowledge how to update property in list c# using linq coworkers, Reach developers & technologists worldwide feed, and. And answer site for professionals, academics, and I keep going back to RSS... Was the Spanish kingdom in America called New Spain if Spain did n't exist a. And increment the Age property by 1 for each object in the filtered.. It to the changed object structured and easy to search whatever strategy you choose is probably totally.. Now I 'd say just use a foreach loop the real changed list JObject... Logo 2023 Stack Exchange Inc ; user contributions licensed under CC BY-SA this would depend on your real.! Reasons why this is pretty close to what I want to avoid loop. Crime against yourself private knowledge with coworkers, Reach developers & technologists share private knowledge with coworkers Reach., but I want but a little.. involved and I keep going back to this 's. Responding to other answers me, and students working within the systems development cycle. To increment the Age property by 1 for each object in the requests Country! Need the value in dimTemp not to change a look up column the changed object am! Similar way approach this would depend on your real class 4 from the list... List we need ID and the Country names a copy of immutable instance with properties!