I have a problem mapping json to CoreData and reading it out again. I map from json to an Activity-Entity with a relationship of last participant entities. The last_particpants is an array with the most recent participants, ordered from most recent first by the API.
{
"id": 50,
"type": "Initiative",
"last_participants": [
{
"id": 15,
"first_name": "Chris",
},
{
"id": 3,
"first_name": "Mary",
},
{
"id": 213,
"first_name": "Dany",
}
]
}
I have RestKit logging on and see that the mapping reads the array elements one by one and keeps the order. However CoreData saves them as an NSSet of entities and then the order gets lost. When I read out the data its is mixed up. What options do I have to keep the order in which the array was mapped? Any help would be great.
2 options:
Use an ordered set in Core Data (set on the attribute in the properties inspector).
Use the #metadata provided by RestKit to access the collection order during mapping.
Related
I am adding a feature that allows users to select from a list of people of a certain type, Type1 and Type2. A type would be chosen from a dropdown, and the data from the API would look like
{
"id": 1,
"name": "TYPE1",
"desc": "Type 1 Person"
}
I am creating a POST endpoint that allows an admin user to insert more people into the list, but I'm unsure on the best way for the admin to include the person's type. In other languages/frameworks, I would do something like this:
{
"first_name": "John",
"last_name": "Doe",
"type_id": 1
}
then handle adding the entry in my own SQL. In Spring though, I'm trying to leverage an object being created from the data automatically. For this to be successful, I've need to send the data as:
{
"first_name": "John",
"last_name": "Doe",
"type": {
"id": 1,
"name": "TYPE1",
"desc": "Type 1 Person"
}
}
My question is in two parts.
In Spring, is there anything I can leverage that would allow me to just pass an identifier for person type when creating a new person entry? (I've looked into DTOs, but I've never used them, so I don't know if that is the proper solution)
In REST in general, how much data should be required when adding a resource that references another resource?
I am using PouchDB (with a Cloudant remote database) to have a local database in a dictionary web app.
I need to have an index with a custom Pashto alphabet order (using Arabic unicode letters).
The localdb.find queries with $gte (alphabetically searching with partial words) do not work well because of the irregular Unicode characters in the Pashto alphabet.
Is it possible to create a custom sort, based on the Pashto alphabet, for an index?
See Mango Query Language
In this reference it is mentioned that:
The most important feature of a view result is that it is sorted by key.
Assume you have a database consisting of docs with a unicodeString field inside each doc. So a sample doc would look like below:
{
"_id":"2018-01-30-18-04-11",
"_rev":"AE19EBC7654",
"title":"Hello elephant",
"unicodeString":"שלום פיל",
}
Now you can have a CouchDB view with a map function like this:
function(doc) {
emit(doc.unicodeString, doc.title); // doc.unicodeString is key
// doc.title is value
}
The above view sorts all the docs inside the database according to its key which is doc.unicodeString. Therefore, if you use the above view, all of your docs would be sorted based on your Unicode string inside docs.
If you have 3 docs in database, when you query the above view, you receive a response result like this in which rows array is sorted according to key in each row:
{
"total_rows": 3,
"offset": 0,
"rows": [
{
"key": "ארץ",
"id": "2017-09-01-09-05-11",
"value": "Earth"
},
{
"key": "בין",
"id": "2015-01-19-11-30-28",
"value": "between"
},
{
"key": "שלום פיל",
"id": "2018-01-30-18-04-11",
"value": "Hello elephant"
}
]
}
I've an object like it (simplified here), Each strain have many chromosomes, that have many locus, that have many features, that have many products, ... Here I just put 1 of each.
The structure in json is:
{
"name": "my strain",
"public": false,
"authorized_users": [1, 23, 51],
"chromosomes": [
{
"name": "C1",
"locus": [
{
"name": "locus1",
"features": [
{
"name": "feature1",
"products": [
{
"name": "product1"
//...
}
]
}
]
}
]
}
]
}
I want to add this object in Elasticsearch, for the moment I've add objects separatly: locus, features and products. It's okay to do a search (I want type a keyword, watch in name of locus, name of features, and name of products), but I need to duplicate data like public and authorized_users, in each subobject.
Can I register the whole object in elasticsearch and just do a search on each locus level, features and products ? And get it individually ? (no return the Strain object)
Yes you can search at any level (ie, with a query like "chromosomes.locus.name").
But as you have arrays at each level, you will have to use nested objects (and nested query) to get exactly what you want, which is a bit more complex:
https://www.elastic.co/guide/en/elasticsearch/reference/current/nested.html
https://www.elastic.co/guide/en/elasticsearch/reference/5.3/query-dsl-nested-query.html
For your last question, no, you cannot get subobjects individually, elastic returns the whole json source object.
If you want only data from subobjects, you will have to use nested aggregations.
I have a MongoDB document structure like this
{
"_id": "002",
"list": [
{
"year": "2015",
"entries": [{...}, {...}]
},
{
"year": "2014",
"entries": [{...}, {...}]
}
]
}
I want to push a new element into "entries". I know it is possible using
collection.updateOne(
Filters.eq("_id", "002"),
new Document("$push", new Document("list.0.entries", "{...}")
);
But this appends to "entries" of the 1st element of "list". I want to append to "entries" for the "year" 2015. How can I do this with MongoDB Java driver API (3.0)?
I think you should use something like
Filters.and(Filters.eq("_id", "002"), Filters.eq("list.year", "2015"))
PS As the Filters javadoc suggests, it's convenient to use static import for it (to make it less verbose by skipping the "Filters." part)
You can use
Bson filter = Filters.and(Filters.eq("_id", "002"), Filters.eq("list", Filters.eq($elemMatch, Filters.eq("year", "2015"))
Document list = collection.find().filter(filter)
Afterwards you can iterate through the list to find the year 2015 and get the entries for this one and insert the new element via java code. Keep the updated list in a local variable and write this one through an update command into your mongoDB.
I'm trying to remove a key from a RethinkDB document.
My approaches (which didn't work):
r.db('db').table('user').replace(function(row){delete row["key"]; return row})
Other approach:
r.db('db').table('user').update({key: null})
This one just sets row.key = null (which looks reasonable).
Examples tested on rethinkdb data explorer through web UI.
Here's the relevant example from the documentation on RethinkDB's website: http://rethinkdb.com/docs/cookbook/python/#removing-a-field-from-a-document
To remove a field from all documents in a table, you need to use replace to update the document to not include the desired field (using without):
r.db('db').table('user').replace(r.row.without('key'))
To remove the field from one specific document in the table:
r.db('db').table('user').get('id').replace(r.row.without('key'))
You can change the selection of documents to update by using any of the selectors in the API (http://rethinkdb.com/api/), e.g. db, table, get, get_all, between, filter.
You can use replace with without:
r.db('db').table('user').replace(r.row.without('key'))
You do not need to use replace to update the entire document.
Here is the relevant documentation: ReQL command: literal
Assume your user document looks like this:
{
"id": 1,
"name": "Alice",
"data": {
"age": 19,
"city": "Dallas",
"job": "Engineer"
}
}
And you want to remove age from the data property. Normally, update will just merge your new data with the old data. r.literal can be used to treat the data object as a single unit.
r.table('users').get(1).update({ data: r.literal({ age: 19, job: 'Engineer' }) }).run(conn, callback)
// Result passed to callback
{
"id": 1,
"name": "Alice",
"data": {
"age": 19,
"job": "Engineer"
}
}
or
r.table('users').get(1).update({ data: { city: r.literal() } }).run(conn, callback)
// Result passed to callback
{
"id": 1,
"name": "Alice",
"data": {
"age": 19,
"job": "Engineer"
}
}