Could you provide the "ObjectMapper.treeToValue(TreeNode, TypeReference)" method?

[fantasy0v0]

Is your feature request related to a problem? Please describe.

The situation now is that without this overloaded method, I need to write extra code to achieve the result I want.

ObjectMapper mapper = new ObjectMapper();
ArrayNode node = mapper.createArrayNode();
node.add("123").add("456");
JavaType javaType = mapper.constructType(new TypeReference<List<String>>() {});
try {
    mapper.treeToValue(node, javaType);
} catch(Exception e) {
    e.printStackTrace();
}

Describe the solution you'd like

Could you provide this method to simplify my code?

Like the code below.

ObjectMapper mapper = new ObjectMapper();
ArrayNode node = mapper.createArrayNode();
node.add("123").add("456");
try {
    mapper.treeToValue(node, new TypeReference<List<String>>() {});
} catch(Exception e) {
    e.printStackTrace();
}

Usage example

No response

Additional context

No response

[cowtowncoder]

This seems like something that could be an easy PR for someone looking for things to tackle; will label as such.

[timnick-snow]

convertValue may helpful

        ObjectMapper mapper = new ObjectMapper();
        ArrayNode node = mapper.createArrayNode();
        node.add("123").add("456");
        try {
            List<String> list = mapper.convertValue(node, new TypeReference<List<String>>() {
            });
        } catch(Exception e) {
            e.printStackTrace();
        }

[JooHyukKim]

convertValue may helpful

Are you suggesting method name changed to convertValue? Or is there more to it. Asking just to make things clear.

@timnick-snow

[timnick-snow]

convertValue may helpful转换值可能有帮助

Are you suggesting method name changed to convertValue? Or is there more to it. Asking just to make things clear.您是否建议将方法名称更改为 convertValue ？或者还有更多的事情要做。询问只是为了把事情说清楚。

No. 'convertValue' is an existing method. When fromValue is 'JsonNode', it should be equivalent to 'treeToValue'. But I'm not sure if there is a performance difference between them at the moment, as 'convertValue' seems to need to be serialized first. When fromValue is 'JsonNode', can this step be omitted?

@JooHyukKim

[JooHyukKim]

first. When fromValue is 'JsonNode', can this step be omitted?

I think not and there is a reason for it. I don't remember in which issue or PR, but has been a discussion around it.

[cowtowncoder]

first. When fromValue is 'JsonNode', can this step be omitted?

I think not and there is a reason for it. I don't remember in which issue or PR, but has been a discussion around it.

Actually serialization part can in fact be avoided because it is possible to create JsonParser that directly traverses JsonNode hierarchy.
So there is this performance benefit; although even serialization for convertValue() can avoid actual JSON generation: it will only add values into TokenBuffer, from which JsonParser (token stream) can be accessed.
I don't think performance difference has been measured but I would expect treeToValue() to be slightly faster.

[cowtowncoder]

Fixed via #4056, closing. Will be in 2.16.0