4.3 Associated Id

IsNull判断

Query all TreeNodes with parentId being null, i.e. root nodes.

Java

TreeNodeTable table = TreeNodeTable.$;
List<TreeNode> rootNodes = sqlClient
    .createQuery(table)
    .where(table.parentId().isNull())
    .select(table)
    .execute();

Kotlin

val rootNodes = sqlClient
    .createQuery(TreeNode::class) {
        where(table.parentId.isNull())
        select(table)
    }
    .execute()

tip

In the code above, parentId is automatically generated by Jimmer at compile time based on the many-to-one property TreeNode.parent, even if the developer does not define the @IdView property named parentId.

Judgment of any value

In fact, eq supports null parameters. When the parameter of eq is null, is null is rendered:

caution

Note: The eqIf of java and eq? of kotlin are different, null is considered a dynamic query and does not render any SQL condition.

Java

@Nullable Long parentId = ...Omitted...;

TreeNodeTable table = TreeNodeTable.$;
List<TreeNode> rootNodes = sqlClient
    .createQuery(table)
    .where(table.parentId().eq(parentId))
    .select(table)
    .execute();

Kotlin

val parentId: Long? = ...Omitted...;

val rootNodes = sqlClient
    .createQuery(TreeNode::class) {
        where(table.parentId eq parentId)
        select(table)
    }
    .execute()