conditional

问题 Referencing the answer in this post I added /Views/Shared/DisplayTemplates and added a partial view called ShortDateTime.cshtml as shown below: @model System.DateTime @Model.ToShortDateString() When the model contains a value this works and the formatted date is displayed correctly: @Html.DisplayFor(modelItem => item.BirthDate, "ShortDateTime") However, if a null value is returned a 'System.InvalidOperationException' is thrown. Indicating: {"The model item passed into the dictionary is null,

问题 Is it possible to do conditional regex (like the one described in http://www.regular-expressions.info/conditional.html) in Vim? 回答1: Vim regex does not have this feature, so you will need to use a bit of repetition to create the same behaviour: /\(\%(condition\)\@=then\|\%(condition\)\@!else\) Note that you have to use the condition twice in the Vim version and the lookahead/lookbehind must always be the opposite in the then/else parts otherwise your regex will not be correct. 回答2: Not

问题 I am involved with a software project written in Qt and built with qmake and gcc on Linux. We have to link to a third-party library that is of fairly low quality and spews tons of warnings. I would like to use -W -Wall on our source code, but pass -w to the nasty third-party library to keep the console free of noise and clutter so we can focus on our code quality. In qmake, is there a way to conditionally add CFLAGS/CXXFLAGS to certain files and libraries? 回答1: Jonathan, I think the problem

问题 Given the dplyr workflow: require(dplyr) mtcars %>% tibble::rownames_to_column(var = "model") %>% filter(grepl(x = model, pattern = "Merc")) %>% group_by(am) %>% summarise(meanMPG = mean(mpg)) I'm interested in conditionally applying filter depending on the value of applyFilter . Solution For applyFilter <- 1 the rows are filtered with use of the "Merc" string, without the filter all rows are returned. applyFilter <- 1 mtcars %>% tibble::rownames_to_column(var = "model") %>% filter(model %in%

问题 I'm creating a sproc that will insert rows into a 'staging' table with an insert into + subquery like so: INSERT INTO myStagingTable SELECT col1, col2, col3 FROM myRealTable I need to put a conditional in there somehow to determine if the value from col1 for example already exists on myStagingTable, then don't insert it, just skip that row from myRealTable. is this possible? If so, how would I structure that? TIA 回答1: INSERT INTO myStagingTable SELECT col1, col2, col3 FROM myRealTable rt

问题 I need to filter a dealer based on id and the uncomplete checkins Initially, it returned the dealer based only on id: // TODO: limit checkins to those that are not complete return this.ObjectContext.Dealers .Include("Groups") .Include("Groups.Items") .Include("Groups.Items.Observations") .Include("Groups.Items.Recommendations") .Include("Checkins") .Include("Checkins.Inspections") .Include("Checkins.Inspections.InspectionItems") .Where(d => d.DealerId == id) .FirstOrDefault(); As you can see

问题 I've got a conditional compilation symbol I'm using called "RELEASE", that I indicated in my project's properties in Visual Studio. I want some particular CSS to be applied to elements when the RELEASE symbol is defined, and I was trying to do that from the view, but it doesn't seem to be working. My view code looks like this (shortened a bit for demo purposes): <% #if (RELEASE) %> <div class="releaseBanner">Banner text here</div> <% #else %> <div class="debugBanner">Banner text here</div> <%

问题 Getting a new warning in xcode 8 beta 3. What is wrong with this syntax, or is there a bug in xcode? SwiftyJSON.swift:772:35: Expected ',' joining parts of a multi-clause condition if let errorValue = error where errorValue.code == ErrorNotExist { } 回答1: It seems this feature has been included: 0099-conditionclauses.md Try this: if let errorValue = error, errorValue.code == ErrorNotExist { } 来源： https://stackoverflow.com/questions/38446598/xcode-8-beta-3-expected-joining-parts-of-a-multi

问题 Getting a new warning in xcode 8 beta 3. What is wrong with this syntax, or is there a bug in xcode? SwiftyJSON.swift:772:35: Expected ',' joining parts of a multi-clause condition if let errorValue = error where errorValue.code == ErrorNotExist { } 回答1: It seems this feature has been included: 0099-conditionclauses.md Try this: if let errorValue = error, errorValue.code == ErrorNotExist { } 来源： https://stackoverflow.com/questions/38446598/xcode-8-beta-3-expected-joining-parts-of-a-multi

问题 I was encountering a lot of bugs in my code because I expected this expression: Boolean([]); to evaluate to false. But this wasn't the case as it evaluated to true. Therefore, functions that possibly returned [] like this: // Where myCollection possibly returned [ obj1, obj2, obj3] or [] if(myCollection) { // ... }else { // ... } did not do expected things. Am I mistaken in assuming that [] an empty array? Also, Is this behavior consistent in all browsers? Or are there any gotchas there too?