ForeignKey.kt
/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.room.vo
import androidx.room.migration.bundle.ForeignKeyBundle
/**
* Keeps information about a foreign key.
*/
data class ForeignKey(
val parentTable: String,
val parentColumns: List<String>,
val childFields: List<Field>,
val onDelete: ForeignKeyAction,
val onUpdate: ForeignKeyAction,
val deferred: Boolean
) : HasSchemaIdentity {
override fun getIdKey(): String {
return parentTable +
"-${parentColumns.joinToString(",")}" +
"-${childFields.joinToString(",") {it.columnName}}" +
"-${onDelete.sqlName}" +
"-${onUpdate.sqlName}" +
"-$deferred"
}
fun databaseDefinition(): String {
return "FOREIGN KEY(${joinEscaped(childFields.map { it.columnName })})" +
" REFERENCES `$parentTable`(${joinEscaped(parentColumns)})" +
" ON UPDATE ${onUpdate.sqlName}" +
" ON DELETE ${onDelete.sqlName}" +
" ${deferredDeclaration()}"
}
private fun deferredDeclaration(): String {
return if (deferred) {
"DEFERRABLE INITIALLY DEFERRED"
} else {
""
}
}
private fun joinEscaped(values: Iterable<String>) = values.joinToString(", ") { "`$it`" }
fun toBundle(): ForeignKeyBundle = ForeignKeyBundle(
parentTable, onDelete.sqlName, onUpdate.sqlName,
childFields.map { it.columnName },
parentColumns
)
}