[jira] [Resolved] (DRILL-6672) Drill table functions cannot handle "setFoo" accessors

["Paul Rogers (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DRILL-6672?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Paul Rogers resolved DRILL-6672.
--------------------------------
    Resolution: Not A Problem

Storage and format plugins must be immutable since their entire values are used as keys in an internal map (plugin registry and format plugin tables.) So, no config should have a "setFoo()" method.

> Drill table functions cannot handle "setFoo" accessors
> ------------------------------------------------------
>
>                 Key: DRILL-6672
>                 URL: https://issues.apache.org/jira/browse/DRILL-6672
>             Project: Apache Drill
>          Issue Type: Bug
>    Affects Versions: 1.13.0
>            Reporter: Paul Rogers
>            Assignee: Paul Rogers
>            Priority: Minor
>
> Consider an example format plugin, such as the regex one used in the Drill book. (GitHub reference needed.) We can define the plugin using getters and setters like this:
> {code}
> public class RegexFormatConfig implements FormatPluginConfig {
>   private String regex;
>   private String fields;
>   private String extension;
>   public void setRegex(String regex) { this.regex = regex; }
>   public void setFields(String fields) { this.fields = fields; }
>   public void setExtension(String extension) { this.extension = extension; }
> {code}
> We can then create a plugin configuration using the Drill Web console, the {{bootstrap-storage-plugins.json}} and so on. All work fine.
> Suppose we try to define a configuration using a Drill table function:
> {code}
>       final String sql = "SELECT * FROM table(cp.`regex/simple.log2`\n" +
>           "(type => 'regex',\n" +
>           " extension => 'log2',\n" +
>           " regex => '(\\\\d\\\\d\\\\d\\\\d)-(\\\\d\\\\d)-(\\\\d\\\\d) .*',\n" +
>           " fields => 'a, b, c, d'))";
> {code}
> We get this error:
> {noformat}
> org.apache.drill.common.exceptions.UserRemoteException: PARSE ERROR: 
> can not set value (\d\d\d\d)-(\d\d)-(\d\d) .* to parameter regex: class java.lang.String
> table regex/simple.log2
> parameter regex
> {noformat}
> The reason is that the code that handles table functions only knows how to set public fields, it does not know about the Java Bean getter/setter conventions used by Jackson:
> {code}
> package org.apache.drill.exec.store.dfs;
> ...
> final class FormatPluginOptionsDescriptor {
>   ...
>   FormatPluginConfig createConfigForTable(TableInstance t) {
>     ...
>         Field field = pluginConfigClass.getField(paramDef.name);
>         ...
>         }
>         field.set(config, param);
>       } catch (IllegalAccessException | NoSuchFieldException | SecurityException e) {
>         throw UserException.parseError(e)
>             .message("can not set value %s to parameter %s: %s", param, paramDef.name, paramDef.type)
>             ...
> {code}
> The only workaround is to make all fields public:
> {code}
> public class RegexFormatConfig implements FormatPluginConfig {
>   public String regex;
>   public String fields;
>   public String extension;
> {code}
> Since public fields are not good practice, please modify the table function mechanism to follow Jackson conventions and allow Java Bean style setters. (Or better, fix DRILL-6673 to allow immutable format objects via the use of a constructor.)



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