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 
17 package androidx.room.vo
18 
19 import androidx.room.migration.bundle.ForeignKeyBundle
20 
21 /**
22  * Keeps information about a foreign key.
23  */
24 data 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 {
getIdKeynull30     override fun getIdKey(): String {
31         return parentTable +
32                 "-${parentColumns.joinToString(",")}" +
33                 "-${childFields.joinToString(",") {it.columnName}}" +
34                 "-${onDelete.sqlName}" +
35                 "-${onUpdate.sqlName}" +
36                 "-$deferred"
37     }
38 
databaseDefinitionnull39     fun databaseDefinition(): String {
40         return "FOREIGN KEY(${joinEscaped(childFields.map { it.columnName })})" +
41                 " REFERENCES `$parentTable`(${joinEscaped(parentColumns)})" +
42                 " ON UPDATE ${onUpdate.sqlName}" +
43                 " ON DELETE ${onDelete.sqlName}" +
44                 " ${deferredDeclaration()}"
45     }
46 
deferredDeclarationnull47     private fun deferredDeclaration(): String {
48         return if (deferred) {
49             "DEFERRABLE INITIALLY DEFERRED"
50         } else {
51             ""
52         }
53     }
54 
joinEscapednull55     private fun joinEscaped(values: Iterable<String>) = values.joinToString(", ") { "`$it`" }
56 
toBundlenull57     fun toBundle(): ForeignKeyBundle = ForeignKeyBundle(
58             parentTable, onDelete.sqlName, onUpdate.sqlName,
59             childFields.map { it.columnName },
60             parentColumns
61     )
62 }
63