iphone – Core Data / Cocoa：@distinctUnionOfObjects没有返回可用的NSArray *（ping没有返回值）

25-02-03 30

对于iphone–CoreData/Cocoa：@distinctUnionOfObjects没有返回可用的NSArray*感兴趣的读者，本文将会是一篇不错的选择，我们将详细介绍ping没有返回值，并

对于iphone – Core Data / Cocoa：@distinctUnionOfObjects没有返回可用的NSArray *感兴趣的读者，本文将会是一篇不错的选择，我们将详细介绍ping没有返回值，并为您提供关于asp.net core 3.0 JObject The collection type ''Newtonsoft.Json.Linq.JObject'' is not supported、collection element of type ''CGColorRef _Nullable'' (aka''stuct CGColor*'')is not an Objective-C object、Consider defining a bean of type ''org.springframework.data.redis.connection.RedisConnectionFa...、Could not enlist in transaction on entering meta-aware object的有用信息。

本文目录一览：

iphone – Core Data / Cocoa：@distinctUnionOfObjects没有返回可用的NSArray *（ping没有返回值）
asp.net core 3.0 JObject The collection type ''Newtonsoft.Json.Linq.JObject'' is not supported
collection element of type ''CGColorRef _Nullable'' (aka''stuct CGColor*'')is not an Objective-C object
Consider defining a bean of type ''org.springframework.data.redis.connection.RedisConnectionFa...
Could not enlist in transaction on entering meta-aware object

iphone – Core Data / Cocoa：@distinctUnionOfObjects没有返回可用的NSArray *（ping没有返回值）

我有一个使用Core Data的应用程序,它具有我想要分组的关系.我有我的.xcdatamodel文件生成的NSManagedobject类,并且大部分内容似乎都正常.

鉴于父/子关系,我想做以下事情：

父母有一个孩子的集合.孩子们有一个属性,groupByProperty,我想分组.

以下代码：

NSSet *allChildren = parent.children;
NSArray *groups = [allChildren valueForKeyPath:@"@distinctUnionOfObjects.groupByProperty"];
Child *child = [groups objectAtIndex:x]; //x is the row that I would like to retrieve

尝试设置子指针时产生NSinvalidargumentexception.

但是,当我这样做时：

NSSet *allChildren = parent.children;
NSArray *groups = [[NSArray alloc] initWithArray:[allChildren valueForKeyPath:@"@distinctUnionOfObjects.groupByProperty"]];
Child *child = [groups objectAtIndex:x]; //x is the row that I would like to retrieve

一切正常.

谁能解释这种行为？我很想弄清楚它是如何工作的.

提前感谢您提供的任何帮助……

克里斯

解决方法

所以,我从这个Apple文档得到了我的信息： Set and Array Operators,其中声明“@distinctUnionOfObjects运算符返回一个数组,其中包含通过发送valueForKeyPath：返回到接收器中每个项目返回的不同对象,将键路径传递到数组的右侧操作符“.我假设返回的对象是一个NSArray,因为它说“Array”,它应该说“Array或Set”.我将返回的Object更改为NSSet,然后使用[[groups allObjects] objectAtIndex：x]将我的对象从那里取出.

它现在看起来像这样：

NSSet *allChildren = parent.children;
NSSet *groups = [allChildren valueForKeyPath:@"@distinctUnionOfObjects.groupByProperty"];
Child *child = [[groups allObjects] objectAtIndex:x]; //x is the row that I would like to retrieve

感谢您的帮助,我想我只需要更仔细地查看异常,这里的关键是“ – [NSCFSet objectAtIndex：…..”

asp.net core 3.0 JObject The collection type ''Newtonsoft.Json.Linq.JObject'' is not supported

在asp.net core 3.0 中,如果直接在Controller中返回 Jobject 类型,会抛出如下错误:


The collection type ''Newtonsoft.Json.Linq.JObject'' is not supported.
System.NotSupportedException: The collection type ''Newtonsoft.Json.Linq.JObject'' is not supported.
at System.Text.Json.JsonPropertyInfoNotNullable`4.GetDictionaryKeyAndValueFromGenericDictionary(WriteStackFrame& writeStackFrame, String& key, Object& value)
at System.Text.Json.JsonPropertyInfo.GetDictionaryKeyAndValue(WriteStackFrame& writeStackFrame, String& key, Object& value)
at System.Text.Json.JsonSerializer.HandleDictionary(JsonClassInfo elementClassInfo, JsonSerializerOptions options, Utf8JsonWriter writer, WriteStack& state)
at System.Text.Json.JsonSerializer.Write(Utf8JsonWriter writer, Int32 originalWriterDepth, Int32 flushThreshold, JsonSerializerOptions options, WriteStack& state)
at System.Text.Json.JsonSerializer.WriteAsyncCore(Stream utf8Json, Object value, Type inputType, JsonSerializerOptions options, CancellationToken cancellationToken)
at Microsoft.AspNetCore.Mvc.Formatters.SystemTextJsonOutputFormatter.WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)
at Microsoft.AspNetCore.Mvc.Formatters.SystemTextJsonOutputFormatter.WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|29_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()
--- End of stack trace from previous location where exception was thrown ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)

该问题的出现估计与.net 3.0 新引入的System.Text.Json类库有关.

折衷的解决办法是:

使用Content方法将 JObject 类型的返回值转为 ContentResult 类型.

伪代码如下:


[HttpPost]

public ContentResult Method1([FromBody]Param param1)
{

　　JObject result=xxx;

　　return Content(result.ToString());

}

如果有时间,建议跟一下System.Text.Json类库的源码来彻底解决该问题.

collection element of type ''CGColorRef _Nullable'' (aka''stuct CGColor*'')is not an Objective-C object

类型转换为ID解决问题: “Collection element of type ''CGColorRef'' (aka ''struct CGColor *'') is not an Objective-C object”

编译器理解Objective-C方法返回的核心基础类型遵循历史可命名约定（见-高级内存管理编程指南）。例如，编译器知道，在iOS的cgcolor返回用UIColor的cgcolor方法不拥有。您必须仍然使用一个合适的类型转换，

1down voteaccepted

It is documented in the "Transitioning to ARC Release Notes":

The compiler understands Objective-C methods that return Core Foundation types follow the historical Cocoa naming conventions (see Advanced Memory Management Programming Guide). For example, the compiler knows that, in iOS, the CGColor returned by the CGColor method of UIColor is not owned. You must still use an appropriate type cast, as illustrated by this example:
NSMutableArray *colors = [NSMutableArray arrayWithObject:(id)[[UIColor darkGrayColor] CGColor]];
[colors addObject:(id)[[UIColor lightGrayColor] CGColor]];

参考:http://stackoverflow.com/questions/21933209/why-type-cast-to-id-will-get-rid-of-this-error-message-collection-element-of-ty

Consider defining a bean of type ''org.springframework.data.redis.connection.RedisConnectionFa...

Description:

Parameter 0 of method redisTemplate in com.liaojie.cloud.auth.server.config.redis.RedisConfiguration required a bean of type 
''org.springframework.data.redis.connection.RedisConnectionFactory'' that could not be found.


Action:

Consider defining a bean of type ''org.springframework.data.redis.connection.RedisConnectionFactory'' in your configuration.

解决方案：

　　　　<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>

Could not enlist in transaction on entering meta-aware object

不知道大家有没有遇到过类似的问题，hibernete没法open connection

Caused by: javax.ejb.EJBException: Caused by: javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: Could not open connection
    at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1387)
    at org.hibernate.ejb.AbstractEntityManagerImpl.find(AbstractEntityManagerImpl.java:838)
    at org.hibernate.ejb.AbstractEntityManagerImpl.find(AbstractEntityManagerImpl.java:781)
    at org.jboss.as.jpa.container.AbstractEntityManager.find(AbstractEntityManager.java:193)

一般来说，造成Could not open connection有如下原因：

到database的链接当真有问题，这时，你可以往下追述log一般能看到和socket相关的exception
在链接访问database之前抛出了其他异常

这里我的问题是：

Caused by: java.sql.sqlException: javax.resource.ResourceException: IJ000457: Unchecked throwable in managedConnectionReconnected() cl=org.jboss.jca.core.connectionmanager.listener.TxConnectionListener@3459752a[state=norMAL managed connection=org.jboss.jca.adapters.jdbc.local.LocalManagedConnection@33c3112d connection handles=0 lastUse=1464930224060 trackByTx=false pool=org.jboss.jca.core.connectionmanager.pool.strategy.OnePool@13869fdc pool internal context=SemaphoreArrayListManagedConnectionPool@5a8c3626[pool=aswuDS] xaResource=LocalXAResourceImpl@1da914c[connectionListener=3459752a connectionManager=33ae043f warned=false currentXid=null productName=Postgresql productVersion=9.3.3 jndiName=java:/jdbc/aswuDS] txSync=null]
    at org.jboss.jca.adapters.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:151)
    at org.hibernate.ejb.connection.InjectedDataSourceConnectionProvider.getConnection(InjectedDataSourceConnectionProvider.java:70)
    at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:301)
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:214)
    ... 210 more
Caused by: javax.resource.ResourceException: IJ000457: Unchecked throwable in managedConnectionReconnected() cl=org.jboss.jca.core.connectionmanager.listener.TxConnectionListener@3459752a[state=norMAL managed connection=org.jboss.jca.adapters.jdbc.local.LocalManagedConnection@33c3112d connection handles=0 lastUse=1464930224060 trackByTx=false pool=org.jboss.jca.core.connectionmanager.pool.strategy.OnePool@13869fdc pool internal context=SemaphoreArrayListManagedConnectionPool@5a8c3626[pool=aswuDS] xaResource=LocalXAResourceImpl@1da914c[connectionListener=3459752a connectionManager=33ae043f warned=false currentXid=null productName=Postgresql productVersion=9.3.3 jndiName=java:/jdbc/aswuDS] txSync=null]
    at org.jboss.jca.core.connectionmanager.AbstractConnectionManager.reconnectManagedConnection(AbstractConnectionManager.java:650)
    at org.jboss.jca.core.connectionmanager.AbstractConnectionManager.allocateConnection(AbstractConnectionManager.java:513)
    at org.jboss.jca.adapters.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:143)
    ... 213 more
Caused by: javax.resource.ResourceException: IJ000461: Could not enlist in transaction on entering Meta-aware object
    at org.jboss.jca.core.connectionmanager.tx.TxConnectionManagerImpl.managedConnectionReconnected(TxConnectionManagerImpl.java:490)
    at org.jboss.jca.core.connectionmanager.AbstractConnectionManager.reconnectManagedConnection(AbstractConnectionManager.java:645)
    ... 215 more
Caused by: javax.transaction.SystemException: IJ000356: Failed to enlist: java.lang.Throwable: Unabled to enlist resource,see the prevIoUs warnings. tx=TransactionImple < ac,BasicAction: 0:ffff0a8d2f03:7ccc2cac:57510d3d:4ea status: ActionStatus.ABORT_ONLY >
    at org.jboss.jca.core.connectionmanager.listener.TxConnectionListener$TransactionSynchronization.checkEnlisted(TxConnectionListener.java:669)
    at org.jboss.jca.core.connectionmanager.listener.TxConnectionListener.enlist(TxConnectionListener.java:368)
    at org.jboss.jca.core.connectionmanager.tx.TxConnectionManagerImpl.managedConnectionReconnected(TxConnectionManagerImpl.java:483)
    ... 216 more

解决方案是：
在JBoss的configure file里面（standalone.xml或host.xml）的system properties加入下面这条：

<property name="com.arjuna.ats.arjuna.allowMultipleLastResources" value="true"/>

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