一、update-model记录

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model类有很多属性，想要更新某个字段，那是否要增加个函数呢？如要再要更新另一个字段，还得再额外增加function

。这样增加冗余代码。看一看realm是怎么处理的

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class RealmManager {
	    private var realmConfig: RealmConfiguration = RealmConfiguration.Builder()
           .name("simple_realm")
           .build()


		var realm: Realm = Realm.getInstance(realmConfig)
		get() = Realm.getInstance(realmConfig)

		private constructor()

		companion object {
			@Volatile private var INSTANCE: RealmManager? = null
			fun getInstance() : RealmManager {
				return INSTANCE?: synchronized(this) {
					INSTANCE?: RealmManager().also { INSTANCE = it }
				}
			}
		}

		fun getVersion() : Version{

			var version = realm.where(Version::class.java).findFirst()
			if (version == null) {
					version = Version()
					realm.executeTransaction {
						it.insert(version)
						//it.insertOrUpdate()
					}
				}
				return version!!
			}

		fun getRawVersion() : Version{
			var version = getVersion()
			return realm.copyFromRealm(version)//关键语句
		}

		fun updateVersion(version: Version) {
			realm.executeTransaction {
				it.insertOrUpdate(version)
			}
		}
}

关键点就是： copyFromRealm,将从realm数据库里查询出来的Version对象托管，再随意更改该对象的值，然后把该对象作为参数传进updateVersion方法即可：

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private fun saveVersion(apkUpgrade: Boolean, rnUpgrade: Boolean, apkVersion: VersionResult, rnVersion: VersionResult) {
	var version = RealmManager.getInstance().getRawVersion()
	if (apkUpgrade) {
		version.apkNewVersionCode = apkVersion.versionCode.toLong()
		version.apkNewVersionName = apkVersion.versionName
	}
	if (rnUpgrade) {
		version.rnNewVersionCode = rnVersion.versionCode.toLong()
		version.rnNewVersionName = rnVersion.versionName
	}
	RealmManager.getInstance().updateVersion(version)
}

getRawVersion方法返回的对象是数据库托管的。
这样就实现了对更改一个model只用一个update方法