zoukankan      html  css  js  c++  java
  • Unique constraint on single String column with GreenDao2

    转:http://software.techassistbox.com/unique-constraint-on-single-string-column-with-greendao_384521.html

    I want to make unique constraint on String value with GreenDao. I have following piece of code:

    Entity category = schema.addEntity('Category');
    category.addIdProperty();
    category.addStringProperty('Name').notNull();

    How can I make sure that Name will be unique?

    My tries:

    I have found methods PropertyBuilder.unique() and PropertyBuilder.index() but none of this works.

    index() doesn't work at all and allows to make duplication. unique() throws exception in Robolectric test but don't do anything when app runs on device Robolectric exception:

    android.database.sqlite.SQLiteException: Cannot execute for last inserted row ID, base error code: 19
        at org.robolectric.shadows.ShadowSQLiteConnection.rethrow(ShadowSQLiteConnection.java:48)
        at org.robolectric.shadows.ShadowSQLiteConnection.access$500(ShadowSQLiteConnection.java:26)
        at org.robolectric.shadows.ShadowSQLiteConnection$Connections.execute(ShadowSQLiteConnection.java:436)
        at org.robolectric.shadows.ShadowSQLiteConnection.nativeExecuteForLastInsertedRowId(ShadowSQLiteConnection.java:239)
        at android.database.sqlite.SQLiteConnection.nativeExecuteForLastInsertedRowId(SQLiteConnection.java)
        at android.database.sqlite.SQLiteConnection.executeForLastInsertedRowId(SQLiteConnection.java:782)
        at android.database.sqlite.SQLiteSession.executeForLastInsertedRowId(SQLiteSession.java:788)
        at android.database.sqlite.SQLiteStatement.executeInsert(SQLiteStatement.java:86)
        at de.greenrobot.dao.AbstractDao.executeInsert(AbstractDao.java:348)
        at de.greenrobot.dao.AbstractDao.insert(AbstractDao.java:293)

    So far I have made something like this but I don't think it's the best solution. 

    However if this correct, is it good idea to add index() to name Property to get better performance?

     

    public Long insert(Category category) {
        if (getByName(category.getName()) != null) {
            throw new DuplicateCategoryNameException(category.getName());
        }
        ...
    }
    
    public Category getByName(String name) {
        return categoryDao.queryBuilder().where(CategoryDao.Properties.Name.eq(name)).build().unique();
    }
  • 相关阅读:
    windows下安装elasticsearch和elasticsearch-head
    Java学习第四天之标识符与关键字
    Java学习第三天之注释
    Java学习第二天之Java程序的基本规则
    Java学习第一天之简单了解java语言及开发环境的安装
    rhel7下安装EPEL源
    Mac OS Catalina 如何删除自带的应用
    jetbrains全系列可用2018
    Windows中zabbix-agent的安装与卸载
    jumpserver修改账号密码以及jumpserver安装教程
  • 原文地址:https://www.cnblogs.com/liulipeng/p/3935919.html
Copyright © 2011-2022 走看看