そのドアはひとりでにかぎがかかる。

that (something or someone distant from the speaker, close to the listener; actions of the listener, or ideas expressed or understood by the listener); the; um...; er...; uh...

door (Western-style)

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

by itself; automatically; naturally

hook; hook bracket (Japanese quotation mark)

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

to take (a resource, e.g. time or money); to hang; to come into view; to arrive; to come under (a contract, a tax); to start (engines, motors); to attend; to deal with; to handle; to have started to; to be on the verge of; to overlap (e.g. information in a manual); to cover; to (come) at; to be fastened; to be covered (e.g. with dust, a table-cloth, etc.); to be caught in; to get a call; to depend on