tuple_object[field-path]

object tuple_object¶

<tuple_object>[field-path]¶

If t is a tuple instance, t['path'] will return the field or subset of fields that are in path. path must be a well formed JSON specification. path may contain field names if the tuple has been retrieved from a space that has an associated format.

To prevent ambiguity, Tarantool first tries to interpret the request as tuple_object[field-number] or tuple_object[field-name]. If and only if that fails, Tarantool tries to interpret the request as tuple_object[field-path].

The path must be a well formed JSON specification, but it may be preceded by ‘.’. The ‘.’ is a signal that the path acts as a suffix for the tuple.

The advantage of specifying a path is that Tarantool will use it to search through a tuple body and get only the tuple part, or parts, that are actually necessary.

In the following example, a tuple named t is returned from replace and then only the relevant part (in this case, matching a name) of a relevant field is returned. Namely: the second field, its third item, the value following ‘key=’.

tarantool> format = {}
---
...
tarantool> format[1] = {name = 'field1', type = 'unsigned'}
---
...
tarantool> format[2] = {name = 'field2', type = 'array'}
---
...
tarantool> s = box.schema.space.create('test', {format = format})
---
...
tarantool> pk = s:create_index('pk')
---
...
tarantool> field2_value = {1, "ABC", {key="Hello", value="world"}}
---
...
tarantool> t = s:replace{1, field2_value}
---
...
tarantool> t["[2][3]['key']"]
---
- Hello
...