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Cryptocurrency Ethereum Mastering Development

Compilation Error

Hi guys I got this error when I try to compile using truffle develop. truffle(develop)> compile Compiling your contracts… Compiling ./contracts/StarNotary.sol /mnt/d/Blockchain/Project2Test/node_modules/openzeppelin-solidity/contracts/token/ERC721/ERC721.sol:3:1: ParserError: Source file requires different compiler version (current compiler is 0.5.16+commit.9c3226ce.Emscripten.clang – note that nightly builds are considered to be strictly less than the released version pragma solidity ^0.6.0; ^———————^ Error: Truffle is […]

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Linux Mastering Development

How to make “ls -Al” work the old way?

In CentOS 6.9 final, ls -Al lists files by ASCII code order, and files starting with a dot(the hidden files) will be displayed on the top of the output. But when I upgraded to CentOS 7.5, ls -Al doesn’t put the hidden files on the top. It seems like the starting dot of the hidden […]

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Linux Mastering Development

Why is Bourne shell considered obsolete?

Is the relation between Bourne shell and Bash similar to that of C and C++? Whenever I read something about shells it always says that Bourne shell is dead and obsolete, but why? I run Bourne shell on my desktop and it does it’s job fine, but then again I also write my code using […]

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Linux Mastering Development

How to block China and keep it blocking after reboot? Having problems in implementation

I am trying to use this solution. I am running Centos 7 and iptables v1.4.21. My script looks like this: # Create the ipset list ipset -N china hash:net # remove any old list that might exist from previous runs of this script rm cn.zone # Pull the latest IP set for China wget -P […]

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Linux Mastering Development

systemd service stops logging to systemd-journal after executing dbus as non-root user

Sorry for the confusing title, My current situation is following: I have a normal systemd service running (as root user&privileges). However, the service should alter my regular user’s certain dconf values. Therefore I’m writing the dconf value from the service with help of sudo as follows: sudo -u user dbus-launch dconf write /… The writing […]

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Mastering Development

subset stacked bars chart

I want to display data I have where series of data is subset of others. I want to display it as stacked bar but not sure how to do it, everywhere I see is just series upon another. basically what I try to achieve is that the blue bar will be on top of the […]

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Mastering Development

How can i extract conditional data using json extractor in Jmeter?

Following is the json response that i am getting for one request. " JobStages": [ { "JobStageName": "Screening Phase", "JobStageID": 1, "Message": "", "JobStageIsRequired": true, "JobStageIsAnyRequired": false, "JobStageActivities": [ { "ActivityName": "Phone Call", "ActivityIsRequired": false, "ActivityID": 1, "IsActivityRejected": false }, How can I extract value of ActivityIsRequired for Activity Phone Call using json extractor in […]

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Mastering Development

Which is a better way to search from multiple tables using PDO in PHP?

I have an HTML form where there is a search field to type for a product name, and below are checkboxes, each for one shop where the product name is to be searched. Users can search from multiple shops by checking the boxes. The form sends a GET request to server, where there is a […]

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Mastering Development

Vuex not reactive

I tried to transition from directly using the bindings for my API in a View to putting all that logic in Vuex. I previously just used Vuex to store entities and included the list call as an action. In my view I for example issued the myAPI.create(…) call and then dispatched the list action. This […]

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Mastering Development

MongoTemplate AnnotationBasedPersistentProperty.isWritable concurrency problem

exception stack java.lang.IllegalStateException: Expected lazy evaluation to yield a non-null value but got null! at org.springframework.data.util.Lazy.get(Lazy.java:66) at org.springframework.data.mapping.model.AnnotationBasedPersistentProperty.isWritable(AnnotationBasedPersistentProperty.java:211) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writeProperties(MappingMongoConverter.java:490) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writeInternal(MappingMongoConverter.java:481) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writeInternal(MappingMongoConverter.java:455) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.write(MappingMongoConverter.java:399) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.write(MappingMongoConverter.java:78) at org.springframework.data.mongodb.core.MongoTemplate.toDocument(MongoTemplate.java:1071) at org.springframework.data.mongodb.core.MongoTemplate.doInsertBatch(MongoTemplate.java:1164) at org.springframework.data.mongodb.core.MongoTemplate.insert(MongoTemplate.java:1116) Exception occured after system startup, guess concurrent invoking org.springframework.data.mapping.model.AnnotationBasedPersistentProperty#isWritable.get() caused the problem. Check the code: private final Lazy<Boolean> isWritable = Lazy […]