ForeignKey.kt revision bdc4c86d3dff74f6634a38e2f7b316b0e823a2c8 
1/*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package androidx.room.vo
18
19import androidx.room.migration.bundle.ForeignKeyBundle
20
21/**
22 * Keeps information about a foreign key.
23 */
24data class ForeignKey(val parentTable: String,
25                      val parentColumns: List<String>,
26                      val childFields: List<Field>,
27                      val onDelete: ForeignKeyAction,
28                      val onUpdate: ForeignKeyAction,
29                      val deferred: Boolean) : HasSchemaIdentity {
30    override fun getIdKey(): String {
31        return parentTable +
32                "-${parentColumns.joinToString(",")}" +
33                "-${childFields.joinToString(",") {it.columnName}}" +
34                "-${onDelete.sqlName}" +
35                "-${onUpdate.sqlName}" +
36                "-$deferred"
37    }
38
39    fun databaseDefinition(): String {
40        return "FOREIGN KEY(${joinEscaped(childFields.map { it.columnName })})" +
41                " REFERENCES `$parentTable`(${joinEscaped(parentColumns)})" +
42                " ON UPDATE ${onUpdate.sqlName}" +
43                " ON DELETE ${onDelete.sqlName}" +
44                " ${deferredDeclaration()}"
45    }
46
47    private fun deferredDeclaration(): String {
48        return if (deferred) {
49            "DEFERRABLE INITIALLY DEFERRED"
50        } else {
51            ""
52        }
53    }
54
55    private fun joinEscaped(values: Iterable<String>) = values.joinToString(", ") { "`$it`" }
56
57    fun toBundle(): ForeignKeyBundle = ForeignKeyBundle(
58            parentTable, onDelete.sqlName, onUpdate.sqlName,
59            childFields.map { it.columnName },
60            parentColumns
61    )
62}
63