frankpuppa opened a new issue, #2266:
URL: https://github.com/apache/plc4x/issues/2266
### What happened?
Hello,
I noticed that when reading a DB variable using the S7-light protocol, the
library throws a NullPointerException if the variable is not defined in the DB.
Here is an example of the error:
```java.util.concurrent.CompletionException: java.lang.NullPointerException:
Cannot invoke "org.apache.plc4x.java.api.value.PlcValue.getRaw()" because
"plcValue" is null
at
java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:315)
at
java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:320)
at
java.base/java.util.concurrent.CompletableFuture.uniHandle(CompletableFuture.java:936)
at
java.base/java.util.concurrent.CompletableFuture$UniHandle.tryFire(CompletableFuture.java:911)
at
java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)
at
java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2179)
at
org.apache.plc4x.java.s7light.readwrite.protocol.S7ProtocolLogic.lambda$14(S7ProtocolLogic.java:212)
at
java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:863)
at
java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:841)
at
java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)
at
java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2179)
at
org.apache.plc4x.java.s7light.readwrite.protocol.S7ProtocolLogic.lambda$26(S7ProtocolLogic.java:518)
at
java.base/java.util.function.Consumer.lambda$andThen$0(Consumer.java:65)
at
org.apache.plc4x.java.spi.Plc4xNettyWrapper.decode(Plc4xNettyWrapper.java:194)
at
io.netty.handler.codec.MessageToMessageCodec$1.decode(MessageToMessageCodec.java:67)
at
io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:91)
at
io.netty.handler.codec.MessageToMessageCodec.channelRead(MessageToMessageCodec.java:120)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
at
io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
at
io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:107)
at
io.netty.handler.codec.MessageToMessageCodec.channelRead(MessageToMessageCodec.java:120)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
at
io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
at
io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:346)
at
io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:318)
at
io.netty.handler.codec.ByteToMessageCodec.channelRead(ByteToMessageCodec.java:103)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
at
io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
at
io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1357)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
at
io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:868)
at
io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166)
at
io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:796)
at
io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:732)
at
io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:658)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562)
at
io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:998)
at
io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at
io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:1583)
Caused by: java.lang.NullPointerException: Cannot invoke
"org.apache.plc4x.java.api.value.PlcValue.getRaw()" because "plcValue" is null
at
org.apache.plc4x.java.s7light.readwrite.optimizer.S7BlockReadOptimizer.processReadResponses(S7BlockReadOptimizer.java:342)
at
org.apache.plc4x.java.spi.optimizer.BaseOptimizer.lambda$1(BaseOptimizer.java:112)
at
org.apache.plc4x.java.spi.optimizer.BaseOptimizer.lambda$8(BaseOptimizer.java:205)
at
java.base/java.util.concurrent.CompletableFuture.uniHandle(CompletableFuture.java:934)
```
Unfortunately, this is not ideal, especially when reading multiple variables
at once (such as when polling a device periodically), since the entire request
fails. A better approach would be to populate the response with an empty value
and let the code handle the result based on the PlcResponseCode of the tag.
I’ve made an attempt to solve this issue, and it works well in the tests
I’ve run so far. You can review the changes here:
[commit](https://github.com/apache/plc4x/commit/efa3bef39a7a25c104c74d4af74bc4e66be58a88)
I am willing to open a PR if this looks fine to you.
### Version
v0.13.0
### Programming Languages
- [ ] plc4c
- [ ] plc4go
- [x] plc4j
- [ ] plc4net
- [ ] plc4py
### Protocols
- [ ] AB-Ethernet
- [ ] ADS /AMS
- [ ] BACnet/IP
- [ ] C-Bus
- [ ] CANopen
- [ ] EtherNet/IP
- [ ] Firmata
- [ ] IEC-69870
- [ ] KNXnet/IP
- [ ] Modbus
- [ ] OPC-UA
- [ ] Profinet
- [ ] S7
- [x] S7-light
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