DateTime field returns to string if used in association

I have two objects with one-to-many accociation, based on date ("date" type column in all two objects):

@ORM\JoinColumn(name="date", referencedColumnName="date"),

When I establish accociation, I get strange behaviour — without association date was DateTime, after — string.

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Field	Original Value	New Value
Description	I have two objects with one-to-many accociation, based on date ("date" type column in all two objects). @ORM\JoinColumn(name="date", referencedColumnName="date"), When I establish accociation, I get strange behaviour — without association date was DateTime, after — string.	I have two objects with one-to-many accociation, based on date ("date" type column in all two objects): {code} @ORM\JoinColumn(name="date", referencedColumnName="date"), {code} When I establish accociation, I get strange behaviour — without association date was DateTime, after — string.