ingest-node.asciidoc - Clarify json processor
Add examples for the json processor.
@@ -1510,15 +1510,72 @@ Converts a JSON string into a structured JSON object.
| `add_to_root` | no | false | Flag that forces the serialized json to be injected into the top level of the document. `target_field` must not be set when this option is chosen.
|======
+Suppose you provide this configuration of the `json` processor:
+
+[source,js]
+--------------------------------------------------
+{
+ "json" : {
+ "field" : "string_source",
+ "target_field" : "json_target"
+ }
+}
+--------------------------------------------------
+
+If the following document is processed:
+
+[source,js]
+--------------------------------------------------
+{
+ "string_source": "{\"foo\": 2000}"
+}
+--------------------------------------------------
+
+after the `json` processor operates on it, it will look like:
+
+[source,js]
+--------------------------------------------------
+{
+ "string_source": "{\"foo\": 2000}",
+ "json_target": {
+ "foo": 2000
+ }
+}
+--------------------------------------------------
+
+If the following configuration is provided, omitting the optional `target_field` setting:
[source,js]
--------------------------------------------------
{
"json" : {
- "field": "{\"foo\": 2000}"
+ "field" : "source_and_target"
+ }
+}
+--------------------------------------------------
+
+then after the `json` processor operates on this document:
+
+[source,js]
+--------------------------------------------------
+{
+ "source_and_target": "{\"foo\": 2000}"
+}
+--------------------------------------------------
+
+it will look like:
+
+[source,js]
+--------------------------------------------------
+{
+ "source_and_target": {
+ "foo": 2000
}
}
--------------------------------------------------
+This illustrates that, unless it is explicitly named in the processor configuration, the `target_field`
+is the same field provided in the required `field` configuration.
+
[[kv-processor]]
=== KV Processor
This processor helps automatically parse messages (or specific event fields) which are of the foo=bar variety.
