Trouble with Spring @ConfiurationProperties extending Mao

Question

I am trying to load come properties from config using the Spring @Configuration & @ConfigurationProperties combination. I have a POJO that extends HashMap<Integer, String> and has a single variable inside. (See MyConfigPojo below). From the .yaml file, I have the same shape. However, when booting up the app, I get an error when trying to parse the string for the defaultValue into an Integer.

@Configuration
@ConfigurationPropeties(prefix = "my-config")
public class MyConfigPojo extends HashMap<Integer, String> {

  private String defaultValue;

  private String getValueForIdOrDefault(int id); // this.get(id) OR ELSE defaultValue
}

In config I have this:

myConfig:
  1: "my first value"
  23: "my 23rd value"
  defaultValue: "cheese"

Which results in a

APPLICATION FAILED TO START
Description:
Failed to bind properties under 'myPackage' to MyConfigPojo:
Property: myConfig[1]
Value: cheese

I thought that was weird, so I turned on TRACE logs and found this:

99 common frames omittedCaused by: java.lang.NumberFormatException: For input string: "defaultValue" at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)

Is there a way to intercept reading this file or to tell Spring how to set the values properly?

What are trying to do? jus want to read the properties from yaml to map right? — Dinesh Dontha, Sep 01 '20 at 17:23
Basically I will have a list of these Int -> String maps each with its own default value that I'd like to be read from config. e.g.:`[{1: "firstMapValueForKey1", 4: "fistMapValaueForKey4", defaultValue: "defaultValueForFirstMap"}, {2: "secondMapValueForKey2", 9: "secondMapValueForKey9", defaultValue: "secondMapDefaultValue"}]` — C Taylor, Sep 01 '20 at 17:25
Your actual problem is using trying to read a map value a: b(key: value), so you have to keep the key type consistent, initially you are using integer, But defaultValue is string, so you are getting NumberFormatException — Dinesh Dontha, Sep 01 '20 at 17:33
I know that I can just change the type of the Map and would get rid of the problem. I am trying to see if there's a way not to do it that way. e.g. with @ConfigurationPropetiesBinding — C Taylor, Sep 01 '20 at 17:46
Oh great, you did not mention anything about this annotation @ConfigurationPropetiesBinding in question. Anyway, goodluck — Dinesh Dontha, Sep 01 '20 at 17:48

Dinesh Dontha · Answer 1 · 2020-09-01T18:40:45.877

You are trying to read a Map from .yml file, for that, you need @ConfigurationProperties annotation enough, don't need @Configuration annotation(if using spring boot). If you are using spring-framework, you need @Configuration also.

Use this example:

myConfig:
  map:
    1: "my first value"
    23: "my 23rd value"
    defaultValue: "cheese"

MyConfigPojo.java

package com.org;


import org.springframework.boot.context.properties.ConfigurationProperties;

import java.util.HashMap;

@Configuration
@ConfigurationProperties(prefix = "my-config")
public class MyConfigPojo {

    private HashMap<String, String> map;

    public HashMap<String, String> getMap() {
        return map;
    }

    public void setMap(HashMap<String, String> map) {
        this.map = map;
    }
}

Now, you can Autowire this MyConfigPojo class anywhere(for instance, in controller class) and read those map keys and values.

@Autowired
MyConfigPojo pojo;

Now, you have considered keys & Values as String datatype for that Map, you will not get NumberFormatException.

Good to know about `@Configuration`. I know I can switch the Map from `` to ``, but I am trying to find a way around that. e.g. using some form of @ConfigurationPropertiesBinding — C Taylor, Sep 01 '20 at 17:47
When I removed the `@Configuration` annotation, I started receiving this error `Field myPojo in mypackage required a bean of type 'myPackage.MyPojo' that could not be found. — C Taylor, Sep 01 '20 at 18:25
Yeah, if you are using spring boot, you dont need it. In Spring, you need it. — Dinesh Dontha, Sep 01 '20 at 18:30

Trouble with Spring @ConfiurationProperties extending Mao

1 Answers1