使用c＃驱动程序在Cassandra中将UDT元素添加到列表集合的正确方法是什么？

Question

I have a list of UDT, something like:

create table MyTable
{
  ...
  stuff list<frozen<MyType>>,
  ...
}

In my client code, I'd like to append an element to "stuff". Ideally, I'd like to do the following (or something similar):

this.Mapper<MyTable>("SET stuff = stuff + [?] WHERE id = ?", mytype, id);

Unfortunately, this fails with the following error:

Invalid list literal for stuff: bind variables are not supported inside collection literals

I can get this to work by converting mytype to json, with something like:

var stuffAsJson = stuff.ToJson();
var update = string.Format("SET stuff = stuff + [{0}] WHERE id = ?", commentAsJson);
this.Mapper.Update<MyTable>(update, stuffAsJson, id);

However, it was tricky to know how to convert the object to json (for example, instead of quoting characters with double quote, they needed to be quoted with single quote).

As such, I am hoping there is a better way to add a type element to a list.

Thanks for your help, Eric

Answer 1

The correct CQL syntax would be:

UPDATE table1 SET stuff = stuff + ? WHERE id = ?

It expects a parameter of type list<MyType> . In your case, it would be:

this.Mapper<MyTable>(
  "SET stuff = stuff + ? WHERE id = ?", new List<MyType> {myItem}, id);