[client-v2] JSON Support

[chernser]

Description

Client should support JSON Data type (https://clickhouse.com/docs/en/integrations/data-formats/json/overview).

Considerations:

• Client should provide convenient API to get access to row data
• Client should have examples of using a few commonly used JSON parsing libraries
• Client should not implement own JSON parser in any way
• Client documentation should list all details of work with JSON format

---

See also:

• Allow to read/write JSON type as binary string in RowBinary format ClickHouse#70288
• https://github.com/Avogar/ClickHouse/blob/master/src/DataTypes/Serializations/SerializationObject.cpp

[dzmitry-biatenia-smop]

@chernser any idea when 0.7.2 Java client will be released?

[chernser]

Hi @dzmitry-biatenia-smop!
We plan to release 0.7.2 by end of November. However this functionality is not in the 0.7.2: it is a complex and experimental feature - so it will take time to add it to the client.
However 0.7.2 might have a minimal support when JSON columns can be read/written as a string.

How would you use JSON? Do you have a DTO object or do you work directly with some generic classes generated by GSON or Jackson ?

Thanks!

[dzmitry-biatenia-smop]

@chernser the basic case - I was able to create a column with JSON type in Clickhouse table with flag allow_experimental_json_type enabled, and even was able to insert some JSON data there with com.clickhouse.client.api.Client#execute(), but when can running any com.clickhouse.client.api.Client.query("select * from table_with_json_column") I'm getting Unsupported format: "JSON" coming from here because response has JSON type here.
I tried to set output_format_binary_write_json_as_string , but seems it's not supported by my version of server 24.8.4

[chernser]

@dzmitry-biatenia-smop
I will fix this issue for sure.

[dzmitry-biatenia-smop]

@chernser are you going to release that fix separately? any ETA for that fix?

[chernser]

@dzmitry-biatenia-smop
patch should be release by end of this week.
release is by end of the month
another option is to take nightly build.

[dzmitry-biatenia-smop]

@chernser can you please notify me when that patch is ready or point me to the correct nightly build?

[chernser]

@dzmitry-biatenia-smop
yes, sure!

[chernser]

Good day, @dzmitry-biatenia-smop ! I've just merged the JSON support (see example).
Nightly build should be ready in a several minutes. Here is how to use it https://gist.github.com/chernser/b4eacfde70093847449e3aef8e51ae8e