Fix prepared_statement_bind_values to resolve nested event's fields (#76)

JDBC streaming filter uses the setting `prepared_statement_bind_values` to bind event's fields or constants to SQL prepared statements. It resolves fields with the notation `[field_name]` but it's not able to match the nested form: `[field][nested]`, this PR changes the match regexp to fix it.

Author: andsel

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 5.1.2
+  -  Fix `prepared_statement_bind_values` in streaming filter to resolve nested event's fields[#76](https://github.com/logstash-plugins/logstash-integration-jdbc/pull/76)
+
 ## 5.1.1
   - [DOC] Changed docs to indicate that logstash-jdbc-static requires local_table [#56](https://github.com/logstash-plugins/logstash-integration-jdbc/pull/56). Fixes [#55](https://github.com/logstash-plugins/logstash-integration-jdbc/issues/55).
 

lib/logstash/plugin_mixins/jdbc_streaming/parameter_handler.rb

@@ -26,7 +26,7 @@ def self.build_bind_value_handler(given_value)
         return InterpolatedParameter.new(given_value)
       end
 
-      if given_value =~ /\A\s*\[[^\]]+\]\s*\z/
+      if given_value =~ /\A(\s*\[[^\]]+\]\s*)*\z/
         return FieldParameter.new(given_value)
       end
 

logstash-integration-jdbc.gemspec

@@ -1,6 +1,6 @@
 Gem::Specification.new do |s|
   s.name = 'logstash-integration-jdbc'
-  s.version         = '5.1.1'
+  s.version         = '5.1.2'
   s.licenses = ['Apache License (2.0)']
   s.summary         = "Integration with JDBC - input and filter plugins"
   s.description     = "This gem is a Logstash plugin required to be installed on top of the Logstash core pipeline using $LS_HOME/bin/logstash-plugin install gemname. This gem is not a stand-alone program"

spec/plugin_mixins/jdbc_streaming/parameter_handler_spec.rb

@@ -0,0 +1,23 @@
+# encoding: utf-8
+require "logstash/devutils/rspec/spec_helper"
+require "logstash/plugin_mixins/jdbc_streaming/parameter_handler"
+
+
+describe LogStash::PluginMixins::JdbcStreaming::ParameterHandler do
+  context "resolve field reference" do
+    let(:event) { ::LogStash::Event.new("field" => "field_value") }
+
+    it "should resolve root field" do
+      handler = LogStash::PluginMixins::JdbcStreaming::ParameterHandler.build_bind_value_handler "[field]"
+      handler.extract_from(event)
+      expect(handler.extract_from(event)).to eq "field_value"
+    end
+
+    it "should resolve nested field" do
+      event = ::LogStash::Event.from_json("{\"field\": {\"nested\": \"nested_field\"}}").first
+      handler = LogStash::PluginMixins::JdbcStreaming::ParameterHandler.build_bind_value_handler "[field][nested]"
+      handler.extract_from(event)
+      expect(handler.extract_from(event)).to eq "nested_field"
+    end
+  end
+end