morphia

问题 I realize that persistence frameworks such as Morphia and Hibernate rely on annotations on domain objects to do their magic. At some level, it seems to me that this is inserting persistence concerns into the domain layer which is something we're supposed to strive to avoid. Is this something that I should try to dodge by perhaps using an external configuration file or maybe separate DTOs from the domain model? Or is this little leak between the persistence and domain layers generally regarded

问题 I'm trying to migrate a PostgreSQL-based application to MongoDB. I'm using Morphia to connect to MongoDB. In my app I have this query to get a list of measurements with Hibernate: ... jpq = jpq.from(qm) .where(qm.parameter.eq(parameter)); jpq = jpq.where(qm.dateTime.between(startDate, endDate)); ... case MINUTE: jpq = jpq.groupBy(qm.dateTime.minute()); case HOUR: jpq = jpq.groupBy(qm.dateTime.hour()); case DAY: jpq = jpq.groupBy(qm.dateTime.dayOfMonth()); case MONTH: jpq = jpq.groupBy(qm

问题 Im tryin to migrate a mysql table to mongodb. My table has 6 million entries. Im using java with morphia. When i save about 1,2 million my memory is almost all consumed. I've read that mongo store the data in memory and after save in disk. Is it possible to send something like a commit to free some amount of memory? 回答1: 1) In terms of durability, you can tell the MongoDB java driver (which Morphia is using), which strategy to use, see https://github.com/mongodb/mongo-java-driver/blob/master

问题 Im tryin to migrate a mysql table to mongodb. My table has 6 million entries. Im using java with morphia. When i save about 1,2 million my memory is almost all consumed. I've read that mongo store the data in memory and after save in disk. Is it possible to send something like a commit to free some amount of memory? 回答1: 1) In terms of durability, you can tell the MongoDB java driver (which Morphia is using), which strategy to use, see https://github.com/mongodb/mongo-java-driver/blob/master

问题 I'm trying to get a collection of MongoDB and convert the records into javabeans using Morphia, but when I try to get the collection of objects (see below in App code), a cast error appears: Exception in thread "main" java.lang.ClassCastException: com.mongodb.BasicDBObject cannot be cast to com.homework.Score Document { "_id" : 19, "name" : "Student 01", "scores" : [ { "type" : "exam", "score" : 44.51211101958831 }, { "type" : "quiz", "score" : 0.6578497966368002 }, { "type" : "homework",

问题 I have a mongo collection which has documents which look like below : { "_id" : ObjectId("9873214jkhdkfjdsf8324"), "nm" : "test", "sts" : 1, "updby" : NumberLong(0), "tags" : [ { "name" : "women", "rank" : 1, "type" : 3 }, { "name" : "men", "rank" : 1 }, { "name" : "clothing", "rank" : 2, "type" : 1 } ] } I want to query the collection such that I want all the documents which have "name": "women" and "type" : 3 inside the tags subdocument of each document which is returned. I know that the

问题 I am debugging a bizarre situation involving MongoDB and two programs. The MongoDB installation in question is initially empty and is a toy deployment. There are two programs. One uses Morphia. The other does not. The non-Morphia-using program inserts a record into a Service collection in a foo-bar database like so: mongo << EOF db.getSiblingDB("foo-bar").getCollection("Service").replaceOne( { "service_name" : "argle-bargle" }, { "_id" : "argle-bargle", "className" : "com.foo.Service",

问题 Please note: although this question mentions Mongo it is surely a pure Groovy question at heart. My MyApp#bootstrap method: def bootstrap(AppConfiguration config) { String h = config.dbHost String p = config.dbPort println "Mongo is at: ${h}:${p}." dao = new MongoDao(host: h, port: p) } My MongoDao class (snippet): class MongoDao implements BasicDao { String dbName Mongo mongo String host String port Morphia morphia Datastore datastore MongoDao(String host, String port) { this.dbName = "db

问题 I'm having a rather interesting issue. When attempting to load a model from a Mongo instance, Morphia throws the following error: [22:17:13 WARN]: Class not found defined in dbObj: java.lang.ClassNotFoundException: me.mattrick.test.storage.TestStat at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[?:1.8.0_101] at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_101] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331) ~[?:1.8.0_101] at java.lang

问题 I have a Morphia schema similar to this one: @Entity class BlogEntry { @Embedded List<BlogComment> comments } @Embedded class BlogComment { String content Long authorId } (code above just for illustration) I'm trying to get a specific BlogComment in order to update it with new content. I have the corresponding BlogEntry object available, and I have the authorId, which let's say for the purposes of this question that these two together are sufficient to uniquely identify the correct