I used to be less in Vue. Today I tried sass on a whim, and then the error will be reported when running sasserror: expected newline
After studying for a long time, I found that there is a pit here. You can’t write sass in style if you use sass in Vue
It has to be written as SCSS
Change it so that you won’t report an error
Consulting area
kofifus：
I am going to switch json.net in the project to the native system. Text. JSON , but I encountered an unexpected error. The test code is as follows:
using System.Text.Json.Serialization;
using Newtonsoft.Json;
public class C {
public C(string PracticeName) { this.PracticeName = PracticeName; }
public string PracticeName;
}
var x = new C("1");
var json = JsonConvert.SerializeObject(x); // returns "{\"PracticeName\":\"1\"}"
var x1 = JsonConvert.DeserializeObject<C>(json); // correctly builds a C
var x2 = System.Text.Json.Serialization.JsonSerializer.Parse<C>(json);
The last line of the above code will report:
Exception thrown: 'System.NullReferenceException' in System.Text.Json.dll Object reference not set to an instance of an object.
What did I do wrong?
I found that this problem can be solved by parameterless constructor , but doing so will put the cart before the horse. Is there a flexible way to realize the simple functions that can be realized by JSON. Net .
Answer area
Christian Gollhardt：
In the . Net core 3.0 stage, the development of system. Text. JSON has not been completely completed. At present, only nonparametric constructor is supported, which may be supported in the future.
If you are migrating the old version to . Net core 3.0 , I still suggest you use newtonsoft. JSON .
Install the microsoft.aspnetcore.mvc.newtonsoftjason package from nuget and inject it into the Services container.
services.AddMvc().AddNewtonsoftJson();
InstallMicrosoft.AspNetCore.SignalR.Protocols.NewtonsoftJson package from Nuget
//Client
new HubConnectionBuilder()
.WithUrl("/chatHub")
.AddNewtonsoftJsonProtocol(...)
.Build();
//Server
services.AddSignalR().AddNewtonsoftJsonProtocol(...);
In this way, you can use json.net in . Net core 3.0 .
user11400447：
To solve this problem, you must make two changes:
praccename
I wrote a console program, in which C1 is converted through newtonsoft. JSON , and C2 is converted through system. Text. JSON .
using Newtonsoft.Json;
namespace TestJsonParse
{
class Program
{
static void Main(string[] args)
{
var c1 = new C1("1");
var json1 = JsonConvert.SerializeObject(c1); // returns "{\"PracticeName\":\"1\"}"
var x1 = JsonConvert.DeserializeObject<C1>(json1); // correctly builds a C1
var c2 = new C2();
string json2 = "{\"PracticeName\":\"1\"}";
var x2 = System.Text.Json.Serialization.JsonSerializer.Parse<C2>(json2); // correctly builds a C2
}
class C1
{
public C1(string PracticeName) { this.PracticeName = PracticeName; }
public string PracticeName;
}
class C2
{
public C2() { }
public string PracticeName { get; set; }
}
}
}
Comment area
Times have changed. I’ve finished system.text.jason, and then I used the latest. Net 5 digression code.
namespace ConsoleApp3
{
class Program
{
static void Main(string[] args)
{
var json = "{\"PracticeName\":\"1\"}";
//json.net
var x1 = JsonConvert.SerializeObject(json);
//System.Text.Json
var x2 = System.Text.Json.JsonSerializer.Deserialize<C>(json);
}
}
public class C
{
public C(string PracticeName) { this.PracticeName = PracticeName; }
public string PracticeName;
}
}
The result is…. Continue to report errors…
What else can I say
It is generally caused by the lack of installation permission of the software package
solve:
1. Put the software package node-v14.17.3-x64.msi on the desktop, download address: https://nodejs.org/en/download/
2. Run as a management manager:
3. Install in the specified directory
C:\Windows>cd C:\Users\pert\Desktop C:\Users\pert\Desktop>msiexec /package node-v14.17.3-x64.msiThis is how to install the software
Next, configure the environment variables and specify the directory
reference resources https://blog.csdn.net/antma/article/details/86104068
When webpack is used normally, I can’t parse the vite icon normally. I don’t know if it’s the feature of vite
Solve the problem of
introducing element's CSS CDN
<link rel="stylesheet" href="https://unpkg.com/element-ui/lib/theme-chalk/index.css">
it’s a series of obsessive-compulsive disorder again!!! Using SCSS style nesting, various highlight o (╥﹏╥) O 
solution: add the following in the settings.json file
"files.associations": {
"*.vue": "vue"
},
First of all, note that @ requestbody accepts the JSON string
so write this
dataType:"json",
contentType: 'application/json',
data: JSON.stringify(data.field),
Instead of @ requestbody, you can directly receive the JSON type
dataType:"json",
data: data.field,
The situation of not using @ requestbody
front end page
$.ajax({
url: "http://localhost:8081/role//saveOrUpdate",
method:"post",
dataType:"json",
// contentType: 'application/json',
data: data.field,
success(data){
console.log("======================")
console.log(data.field)
if(data.code == 200){
layer.msg('add success', function () {
window.location = 'list.html';
});
}
},
error(data){
console.log(data)
if(data.code != 200){
layer.msg(data);
}
}
});
Back end:
@PostMapping("/saveOrUpdate")
public Result saveOrUpdate(Roles roles){
System.out.println(roles);
boolean saveOrUpdate = roleService.saveOrUpdate(roles);
if(saveOrUpdate == true)
return Result.succ(null);
else
return Result.fail("failed to add");
}
Using @ requestbody
front end:
$.ajax({
url: "http://localhost:8081/role//saveOrUpdate",
method:"post",
dataType:"json",
contentType: 'application/json',
data: JSON.stringify(data.field),
success(data){
console.log("======================")
console.log(data.field)
if(data.code == 200){
layer.msg('add success', function () {
window.location = 'list.html';
});
}
},
error(data){
console.log(data)
if(data.code != 200){
layer.msg(data);
}
}
});
back-end
@PostMapping("/saveOrUpdate")
public Result saveOrUpdate(@RequestBody Roles roles){
System.out.println(roles);
boolean saveOrUpdate = roleService.saveOrUpdate(roles);
if(saveOrUpdate == true)
return Result.succ(null);
else
return Result.fail("failed to add");
}
Elmentui form. When setting input type = number, remove the up and down arrows
<style lang="scss" scoped>
/deep/ input[type="number"] {
-moz-appearance: textfield;
}
/deep/ input[type="number"]::-webkit-inner-spin-button,
/deep/ input[type="number"]::-webkit-outer-spin-button {
-webkit-appearance: none;
}
</style>
solve
Method 1: set Axios in main.js method 2: if Axios is encapsulated into request
In the process of doing the project, due to the large amount of data requested, the request timed out, so this error was reported. The timeout time of 5000ms was set when Axios was configured. We can solve this error by changing this setting
Method 1: set Axios in main.js
Set the timeout of Axios in main.js, but it is generally not available. You need to set it yourself. Then main.js can be found under SRC of your project, and add Axios. Default. Timeout = 50000 in it, which means that setting the timeout to 50 seconds should be enough
Method 2: if Axios is encapsulated into request
If the first method is not used at all, you can change it in another setting:
here
1. Error description
[scss/sass] 14:56:38.373 internal/modules/cjs/loader.js:717
[scss/sass] 14:56:38.373 return process.dlopen(module, path.toNamespacedPath(filename));
[scss/sass] 14:56:38.373 ^
[scss/sass] 14:56:38.373 Error: Module did not self-register.
[scss/sass] 14:56:38.373 at Object.Module._extensions..node (internal/modules/cjs/loader.js:717:18)
[scss/sass] 14:56:38.373 at Module.load (internal/modules/cjs/loader.js:598:32)
[scss/sass] 14:56:38.373 at tryModuleLoad (internal/modules/cjs/loader.js:537:12)
[scss/sass] 14:56:38.373 at Function.Module._load (internal/modules/cjs/loader.js:529:3)
[scss/sass] 14:56:38.373 at Module.require (internal/modules/cjs/loader.js:636:17)
[scss/sass] 14:56:38.373 at require (internal/modules/cjs/helpers.js:20:18)
[scss/sass] 14:56:38.373 at module.exports (G:\HBuilderX\plugins\compile-node-sass\node_modules\node-sass-china\lib\binding.js:19:10)
[scss/sass] 14:56:38.373 at Object.<anonymous> (G:\HBuilderX\plugins\compile-node-sass\node_modules\node-sass-china\lib\index.js:14:35)
[scss/sass] 14:56:38.373 at Module._compile (internal/modules/cjs/loader.js:688:30)
[scss/sass] 14:56:38.373 at Object.Module._extensions..js (internal/modules/cjs/loader.js:699:10)2. Error reason
The error message is that the module is not registered and installed with NPM Install, but the result is still an error, indicating that the module has not been successfully installed
G:\HBuilderX\plugins\compile-node-sass\node_modules\node-sass-china\vendor\win32
-x64-64>npm install
> [email protected] install G:\HBuilderX\plugins\compile-node-sass\node_modu
les\node-sass-china
> node scripts/install.js
node-sass build Binary found at G:\HBuilderX\plugins\compile-node-sass\node_modu
les\node-sass-china\vendor\win32-x64-64\binding.node
> [email protected] postinstall G:\HBuilderX\plugins\compile-node-sass\node_
modules\node-sass-china
> node scripts/build.js
Binary found at G:\HBuilderX\plugins\compile-node-sass\node_modules\node-sass-ch
ina\vendor\win32-x64-64\binding.node
Testing binary
Binary has a problem: Error: \\?\G:\HBuilderX\plugins\compile-node-sass\node_mod
ules\node-sass-china\vendor\win32-x64-64\binding.node is not a valid Win32 appli
cation.
\\?\G:\HBuilderX\plugins\compile-node-sass\node_modules\node-sass-china\vendor\w
in32-x64-64\binding.node
at Object.Module._extensions..node (internal/modules/cjs/loader.js:717:18)
at Module.load (internal/modules/cjs/loader.js:598:32)
at tryModuleLoad (internal/modules/cjs/loader.js:537:12)
at Function.Module._load (internal/modules/cjs/loader.js:529:3)
at Module.require (internal/modules/cjs/loader.js:636:17)
at require (internal/modules/cjs/helpers.js:20:18)
at module.exports (G:\HBuilderX\plugins\compile-node-sass\node_modules\node-
sass-china\lib\binding.js:19:10)
at Object.<anonymous> (G:\HBuilderX\plugins\compile-node-sass\node_modules\n
ode-sass-china\lib\index.js:14:35)
at Module._compile (internal/modules/cjs/loader.js:688:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:699:10)
Building the binary locally
Building: F:\nodejs\node.exe G:\HBuilderX\plugins\compile-node-sass\node_modules
\node-sass-china\node_modules\node-gyp\bin\node-gyp.js rebuild --verbose --libsa
ss_ext= --libsass_cflags= --libsass_ldflags= --libsass_library=
gyp info it worked if it ends with ok
gyp verb cli [ 'F:\\nodejs\\node.exe',
gyp verb cli 'G:\\HBuilderX\\plugins\\compile-node-sass\\node_modules\\node-sa
ss-china\\node_modules\\node-gyp\\bin\\node-gyp.js',
gyp verb cli 'rebuild',
gyp verb cli '--verbose',
gyp verb cli '--libsass_ext=',
gyp verb cli '--libsass_cflags=',
gyp verb cli '--libsass_ldflags=',
gyp verb cli '--libsass_library=' ]
gyp info using [email protected]
gyp info using [email protected] | win32 | x64
gyp verb command rebuild []
gyp verb command clean []
gyp verb clean removing "build" directory
gyp verb command configure []
gyp verb check python checking for Python executable "python2" in the PATH
gyp verb `which` failed Error: not found: python2
gyp verb `which` failed at getNotFoundError (G:\HBuilderX\plugins\compile-no
de-sass\node_modules\node-sass-china\node_modules\which\which.js:13:12)
gyp verb `which` failed at F (G:\HBuilderX\plugins\compile-node-sass\node_mo
dules\node-sass-china\node_modules\which\which.js:68:19)
gyp verb `which` failed at E (G:\HBuilderX\plugins\compile-node-sass\node_mo
dules\node-sass-china\node_modules\which\which.js:80:29)
gyp verb `which` failed at G:\HBuilderX\plugins\compile-node-sass\node_modul
es\node-sass-china\node_modules\which\which.js:89:16
gyp verb `which` failed at G:\HBuilderX\plugins\compile-node-sass\node_modul
es\node-sass-china\node_modules\isexe\index.js:42:5
gyp verb `which` failed at G:\HBuilderX\plugins\compile-node-sass\node_modul
es\node-sass-china\node_modules\isexe\windows.js:36:5
gyp verb `which` failed at FSReqWrap.oncomplete (fs.js:154:21)
gyp verb `which` failed python2 { Error: not found: python2
gyp verb `which` failed at getNotFoundError (G:\HBuilderX\plugins\compile-no
de-sass\node_modules\node-sass-china\node_modules\which\which.js:13:12)
gyp verb `which` failed at F (G:\HBuilderX\plugins\compile-node-sass\node_mo
dules\node-sass-china\node_modules\which\which.js:68:19)
gyp verb `which` failed at E (G:\HBuilderX\plugins\compile-node-sass\node_mo
dules\node-sass-china\node_modules\which\which.js:80:29)
gyp verb `which` failed at G:\HBuilderX\plugins\compile-node-sass\node_modul
es\node-sass-china\node_modules\which\which.js:89:16
gyp verb `which` failed at G:\HBuilderX\plugins\compile-node-sass\node_modul
es\node-sass-china\node_modules\isexe\index.js:42:5
gyp verb `which` failed at G:\HBuilderX\plugins\compile-node-sass\node_modul
es\node-sass-china\node_modules\isexe\windows.js:36:5
gyp verb `which` failed at FSReqWrap.oncomplete (fs.js:154:21)
gyp verb `which` failed stack:
gyp verb `which` failed 'Error: not found: python2\n at getNotFoundError (
G:\\HBuilderX\\plugins\\compile-node-sass\\node_modules\\node-sass-china\\node_m
odules\\which\\which.js:13:12)\n at F (G:\\HBuilderX\\plugins\\compile-node-s
ass\\node_modules\\node-sass-china\\node_modules\\which\\which.js:68:19)\n at
E (G:\\HBuilderX\\plugins\\compile-node-sass\\node_modules\\node-sass-china\\no
de_modules\\which\\which.js:80:29)\n at G:\\HBuilderX\\plugins\\compile-node-
sass\\node_modules\\node-sass-china\\node_modules\\which\\which.js:89:16\n at
G:\\HBuilderX\\plugins\\compile-node-sass\\node_modules\\node-sass-china\\node_
modules\\isexe\\index.js:42:5\n at G:\\HBuilderX\\plugins\\compile-node-sass\
\node_modules\\node-sass-china\\node_modules\\isexe\\windows.js:36:5\n at FSR
eqWrap.oncomplete (fs.js:154:21)',
gyp verb `which` failed code: 'ENOENT' }
gyp verb check python checking for Python executable "python" in the PATH
gyp verb `which` succeeded python E:\Python\Python36\python.EXE
gyp ERR! configure error
gyp ERR! stack Error: Command failed: E:\Python\Python36\python.EXE -c import sy
s; print "%s.%s.%s" % sys.version_info[:3];
gyp ERR! stack File "<string>", line 1
gyp ERR! stack import sys; print "%s.%s.%s" % sys.version_info[:3];
gyp ERR! stack ^
gyp ERR! stack SyntaxError: invalid syntax
gyp ERR! stack
gyp ERR! stack at ChildProcess.exithandler (child_process.js:289:12)
gyp ERR! stack at ChildProcess.emit (events.js:182:13)
gyp ERR! stack at maybeClose (internal/child_process.js:962:16)
gyp ERR! stack at Socket.stream.socket.on (internal/child_process.js:381:11)
gyp ERR! stack at Socket.emit (events.js:182:13)
gyp ERR! stack at Pipe._handle.close (net.js:606:12)
gyp ERR! System Windows_NT 6.1.7601
gyp ERR! command "F:\\nodejs\\node.exe" "G:\\HBuilderX\\plugins\\compile-node-sa
ss\\node_modules\\node-sass-china\\node_modules\\node-gyp\\bin\\node-gyp.js" "re
build" "--verbose" "--libsass_ext=" "--libsass_cflags=" "--libsass_ldflags=" "--
libsass_library="
gyp ERR! cwd G:\HBuilderX\plugins\compile-node-sass\node_modules\node-sass-china
gyp ERR! node -v v10.13.0
gyp ERR! node-gyp -v v3.8.0
gyp ERR! not ok
Build failed with error code: 1
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! [email protected] postinstall: `node scripts/build.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the [email protected] postinstall script.
npm ERR! This is probably not a problem with npm. There is likely additional log
ging output above.
npm ERR! A complete log of this run can be found in:
npm ERR! F:\nodejs\node_cache\_logs\2019-01-10T07_40_54_700Z-debug.log
G:\HBuilderX\plugins\compile-node-sass\node_modules\node-sass-china\vendor\win32
-x64-64>3. Solutions
Uninstall and reinstall Sass related modules
C:\Users\Administrator.USER-0GUONPPBHK>npm uninstall node-sass -D
npm WARN Administrator.USER-0GUONPPBHK No repository field.
npm WARN Administrator.USER-0GUONPPBHK No license field.
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: [email protected] (node_modules\fse
vents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@
1.2.4: wanted {"os":"darwin","arch":"any"} (current: {"os":"win32","arch":"x64"}
)
added 33 packages from 16 contributors, removed 22 packages and updated 340 pack
ages in 26.067s
C:\Users\Administrator.USER-0GUONPPBHK>npm install node-sass -D
> [email protected] install C:\Users\Administrator.USER-0GUONPPBHK\node_modules\n
ode-sass
> node scripts/install.js
Cached binary found at F:\nodejs\node_cache\node-sass\4.11.0\win32-x64-64_bindin
g.node
> [email protected] postinstall C:\Users\Administrator.USER-0GUONPPBHK\node_modul
es\node-sass
> node scripts/build.js
Binary found at C:\Users\Administrator.USER-0GUONPPBHK\node_modules\node-sass\ve
ndor\win32-x64-64\binding.node
Testing binary
Binary is fine
npm WARN [email protected] requires a peer of vue@^2.5.2 but none is installed. Y
ou must install peer dependencies yourself.
npm WARN [email protected] requires a peer of vue@^2.5.0 but none is installed.
You must install peer dependencies yourself.
npm WARN Administrator.USER-0GUONPPBHK No repository field.
npm WARN Administrator.USER-0GUONPPBHK No license field.
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: [email protected] (node_modules\fse
vents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@
1.2.4: wanted {"os":"darwin","arch":"any"} (current: {"os":"win32","arch":"x64"}
)
+ [email protected]
added 110 packages from 118 contributors in 26.774s
C:\Users\Administrator.USER-0GUONPPBHK>
After checking some data, it was found that the data was passed from the back end to the front end, and the front end did not handle it well, so an error was reported
Problem: because I want to load a list El table, the required data format is as follows
// Required data format for el-table's :data
[{...} ,{...} ,... ,{...}]
// The format of the data returned by the backend, I returned it directly to :data, which is obviously not correct, it should wrap a []
{...}
Based on this, the way of processing data is not right
// For example, if you deconstruct a res object from the backend, you only need [res] or [res.xx] to solve the problem
// Instance:
getUserByName(name).then(res => {
console(res) // you can look at the format of res in the background, what you really want, and then take it out by way of .xxx
this.userList = [res.data]
})
// I'll go back to el-table here and put :data=userlist to fix it
Consultation area
Naor：
I have the following query:
int maxShoeSize = Workers.Where(x => x.CompanyId == 8)
.Max(x => x.ShoeSize);
If workers. Where (x = & gt; x. Companyid = = 8) if no workers are found, the above code will throw an exception.
Now the idea is: query can return 0 if it can't be found, but don't throw an exception. How can I modify the query above?
Answer area
Ron K.：
You can use the extension method of IEnumerable defaultifempty() to avoid this embarrassment. Refer to the following code.
class Program
{
static void Main(string[] args)
{
List<Worker> Workers = new List<Worker>()
{
new Worker(){ CompanyId=1, CompanyName="tweet", ShoeSize=10 },
new Worker(){ CompanyId=2, CompanyName="google", ShoeSize=20 },
};
int maxShoeSize = Workers.Where(x => x.CompanyId == 8)
.Select(x => x.ShoeSize)
.DefaultIfEmpty(0)
.Max();
Debug.WriteLine($"maxShoeSize={maxShoeSize}");
}
}
class Worker
{
public int CompanyId { get; set; }
public string CompanyName { get; set; }
public int ShoeSize { get; set; }
}
Output results:
maxShoeSize=0
Of course, the above 0 is not necessary. You can change it to any other number.
CptRobby：
Although the plan provided by the man upstairs can work normally, it doesn't look very eye-catching. It can be transformed into the following one.
int maxShoeSize = Workers.Where(x => x.CompanyId == 8)
.Select(x => (int?)x.ShoeSize)
.Max() ?? 0;
Does the code look a little lengthy?The best way is to customize a extension method , as shown in the following code:
public static int MaxOrDefault<T>(this IQueryable<T> source, Expression<Func<T, int?>> selector, int nullValue = 0)
{
return source.Max(selector) ?? nullValue;
}
For simplicity, this extension only deals with the int type. You can change it to any type, such as: (long, double,...), and then you can continue to reform the caller.
int maxShoeSize = Workers.Where(x => x.CompanyId == 8).MaxOrDefault(x => x.ShoeSize);
I hope my answer can help more people.
Comment area
Xiaobian never dares to do Max on the empty collection , after all, it's not once or twice, so every time we judge whether there is a value in the collection in advance, and then execute Max , we didn't expect that there are magic extension methods defaultifempty and empty type that can help us to do it, and we all forget about sensory science????????????.
The problem is as follows: the IP address cannot be accessed
Enter the file “project name – config”- index.js ”Open index.js File, modify parameter
after modification, it can be accessed normally: 
If my article is helpful to you, welcome to like, leave a message and pay attention to it. Thank Sanlian!!!
The problem has not been solved!!! 😘😘😘
CSDN: I heard that you are good at playing
GitHub: zhongzhimao
Coupons: coupons