Spring Boot yaml configuration for a list of strings

Question

I am trying to load an array of strings from application yml file  This is the config   ignore      filenames          -  DS Store         -  hg   This is the class    Value    ignore filenames    private List lt String gt  igonoredFileNames   new ArrayList lt  gt       There are other configurations in the same class that loads just fine  There are no tabs in my yaml file  Still I get the following exception   Caused by  java lang IllegalArgumentException  Could not resolve placeholder  ignore filenames  in string value    ignore filenames

User · Answer

Value    your elements        private String   elements    yml file   your   elements  element1  element2  element3

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use comma separated values in application yml  ignoreFilenames   DS Store   hg   java code for access   Value    ignoreFilenames        String   ignoreFilenames   It is working

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Ahmet s answer provides on how to assign the comma separated values to String array    To use the above configuration in different classes you might need to create getters setters for this    But if you would like to load this configuration once and keep using this as a bean with Autowired annotation  here is the how I accomplished   In ConfigProvider java   Bean  name    ignoreFileNames    ConfigurationProperties   prefix    ignore filenames    public List lt String gt  ignoreFileNames        return new ArrayList lt String gt         In outside classes    Autowired  Qualifier  ignoreFileNames   private List lt String gt  ignoreFileNames    you can use the same list everywhere else by autowiring

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In my case this was a syntax issue in the  yml file   I had    Value    spring kafka bootstrap-servers    public List lt String gt  BOOTSTRAP SERVERS LIST    and the list in my  yml file   bootstrap-servers    - s1 company com 9092   - s2 company com 9092   - s3 company com 9092   was not reading into the  Value-annotated field   When I changed the syntax in the  yml file to   bootstrap-servers  gt    s1 company com 9092   s2 company com 9092   s3 company com 9092   it worked fine

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Value       your elements   split           private Set lt String gt  stringSet    yml file   your   elements  element1  element2  element3   There is lot more you can play with spring spEL

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From the spring boot docs https   docs spring io spring-boot docs current reference html boot-features-external-config html  YAML lists are represented as property keys with  index  dereferencers  for example this YAML   my     servers         - dev bar com        - foo bar com   Would be transformed into these properties   my servers 0  dev bar com my servers 1  foo bar com   To bind to properties like that using the Spring DataBinder utilities  which is what  ConfigurationProperties does  you need to have a property in the target bean of type java util List and you either need to provide a setter  or initialize it with a mutable value  e g  this will bind to the properties above   Here is what the question s code would look like    ConfigurationProperties prefix  ignore   public class Filenames        private List lt String gt  ignoredFilenames   new ArrayList lt String gt          public List lt String gt  getFilenames             return this ignoredFilenames

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In addition to Ahmet s answer you can add line breaks to the coma separated string using  gt  symbol   application yml   ignoreFilenames   gt     DS Store      hg   Java code    Value    ignoreFilenames        String   ignoreFilenames

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Well  the only thing I can make it work is like so    servers   gt      dev example com      another example com   Value    servers    private String   array    And dont forget the  Configuration above your class      Without the     separation  no such luck     Works too  boot 1 5 8 versie   servers          dev example com         another example com

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My guess is  that the  Value can not cope with  complex  types   You can go with a prop class like this    Component  ConfigurationProperties  ignore   class IgnoreSettings       List lt String gt  filenames     Please note  This code is Groovy - not Java - to keep the example short   See the comments for tips how to adopt   See the complete example https   github com christoph-frick so-springboot-yaml-string-list

[spring-boot] Spring Boot yaml configuration for a list of strings

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