I am using Ionic 2 with meteor/MongoDB.
When I do the following, it inserts the chat object into the localChatCollection:
let promise: Promise<Mongo.Collection<Chat>> = this.findChats();
promise.then((data: Mongo.Collection<Chat>) => {
let localChatCollection: Mongo.Collection<Chat> = new Mongo.Collection<Chat>(null);
data.find().forEach(function (chat: Chat) {
console.log('==> ' + chat);
localChatCollection.insert(chat);
});
However, if I define the localChatCollection globally, it does not insert the chat object. There are no errors but the process just stops on the insert line.
private localChatCollection: Mongo.Collection<Chat> = new Mongo.Collection<Chat>(null);
....
this.localChatCollection.insert(chat);
Any ideas how I can get this to insert into a globally defined collection?
This works, but I don't think it is the most elegant solution:
let that = this;
data.find().forEach(function (chat: Chat) {
that.localChatCollection.insert(chat);
});
Related
I have an object with several really large string properties. In addition, it has a simple timestamp property.
What I trying to achieve is to update only timestamp property without getting the whole huge object to the server.
Eventually, I would like to use EF and to do in the most performant way something equivalent to this:
update [...]
set [...] = [...]
where [...]
Using the following, you can update a single column:
var yourEntity = new YourEntity() { Id = id, DateProp = dateTime };
using (var db = new MyEfContextName())
{
db.YourEntities.Attach(yourEntity);
db.Entry(yourEntity).Property(x => x.DateProp).IsModified = true;
db.SaveChanges();
}
OK, I managed to handle this. The solution is the same as proposed by Seany84, with the only addition of disabling validation, in order to overcome issue with required fields. Basically, I had to add the following line just before 'SaveChanges():
db.Configuration.ValidateOnSaveEnabled = false;
So, the complete solution is:
var yourEntity = new YourEntity() { Id = id, DateProp = dateTime };
using (var db = new MyEfContextName())
{
db.YourEntities.Attach(yourEntity);
db.Entry(yourEntity).Property(x => x.DateProp).IsModified = true;
db.Configuration.ValidateOnSaveEnabled = false;
db.SaveChanges();
}
I am doing select dependent and I got a problem when making the query's, here the js
function cargar_paises() {
$.getJSON('cargar_paises', {}, function (data) {
$('#paises').empty();
$('#paises').append('<option value="0">Seleccione ...</option>');
$.each(data, function (id, desc) {
var option = $('<option></option>', {value:(id+1), text:desc});
$('#paises').append(option);
});
});
}
and my view
def cargar_paises(request):
if request.is_ajax:
pais = Pais.objects.all()
paises = []
for s in pais:
aux = []
id = s.pk
aux.append(id)
nombre = s.nombre
aux.append(nombre)
paises.append(aux)
return HttpResponse(json.dumps(paises), mimetype='aplication/json')
the problem is when I print the values in the select and send the id to another query, the values that I take are the index of the select and not the value of id_pais.
You can work this out a little better using a list of dictionaries instead of a list of lists, even using the dJango .values(), but to keep it simple, you ca use you exact same approach,
function cargar_paises() {
$.getJSON('cargar_paises', {}, function (data) {
$('#paises').empty();
$('#paises').append('<option value="0">Seleccione ...</option>');
$.each(data, function (item) {
var option = $('<option></option>', {value:item.id, text:item.nombre});
$('#paises').append(option);
});
});
}
and in the view,
def cargar_paises(request):
if request.is_ajax:
pais = Pais.objects.all()
paises = []
for s in pais:
aux = {}
aux['id'] = s.pk
aux['nombre'] = s.nombre
paises.append(aux)
return HttpResponse(json.dumps(paises), mimetype='aplication/json')
Remember, you can map Python dictionaries to Json objects, and python lists to Json arrays, another good hint is to use django-dajaxice it's a very good tool to do what you want, anyway is good to se this kind of things out of dJango.
Edit
I really thought about it, use the .values() in the query set, your view,
def cargar_paises(request):
if request.is_ajax:
paises = Pais.objects.values('id', 'nombre')
return HttpResponse(json.dumps(paises), mimetype='aplication/json')
you can find the documentation here.
try setting the id's as:
var option = $('<option></option>', {value:(paises[0].aux.id+1), text:desc});
I'd like to compare the new/incoming value of a property with the previous value of that property (what is currently saved in the db) within a pre('save') middleware.
Does Mongoose provide a facility for doing this?
The accepted answer works very nicely. An alternative syntax can also be used, with the setter inline with the Schema definition:
var Person = new mongoose.Schema({
name: {
type: String,
set: function(name) {
this._previousName = this.name;
return name;
}
});
Person.pre('save', function (next) {
var previousName = this._previousName;
if(someCondition) {
...
}
next();
});
Mongoose allows you to configure custom setters in which you do the comparison. pre('save') by itself won't give you what you need, but together:
schema.path('name').set(function (newVal) {
var originalVal = this.name;
if (someThing) {
this._customState = true;
}
});
schema.pre('save', function (next) {
if (this._customState) {
...
}
next();
})
I was looking for a solution to detect changes in any one of multiple fields. Since it looks like you can't create a setter for the full schema, I used a virtual property. I'm only updating records in a few places so this is a fairly efficient solution for that kind of situation:
Person.virtual('previousDoc').get(function() {
return this._previousDoc;
}).set(function(value) {
this._previousDoc = value;
});
Let's say your Person moves and you need to update his address:
const person = await Person.findOne({firstName: "John", lastName: "Doe"});
person.previousDoc = person.toObject(); // create a deep copy of the previous doc
person.address = "123 Stack Road";
person.city = "Overflow";
person.state = "CA";
person.save();
Then in your pre hooks, you would just need to reference properties of _previousDoc such as:
// fallback to empty object in case you don't always want to check the previous state
const previous = this._previousDoc || {};
if (this.address !== previous.address) {
// do something
}
// you could also assign custom properties to _previousDoc that are not in your schema to allow further customization
if (previous.userAddressChange) {
} else if (previous.adminAddressChange) {
}
Honestly, I tried the solutions posted here, but I had to create a function that would store the old values in an array, save the values, and then see the difference.
// Stores all of the old values of the instance into oldValues
const oldValues = {};
for (let key of Object.keys(input)) {
if (self[key] != undefined) {
oldValues[key] = self[key].toString();
}
// Saves the input values to the instance
self[key] = input[key];
}
yield self.save();
for (let key of Object.keys(newValues)) {
if (oldValues[key] != newValues[key]) {
// Do what you need to do
}
}
What I do is use this.constructor within the pre-save route to access the current value in the database.
const oldData = this.constructor.findById(this.id)
You can then grab the specific key you're looking for from the oldData to work with as you see fit :)
let name = oldData.name
Note that this works well for simple data such as strings, but I have found that it does not work well for subschema, as mongoose has built in functionality that runs first. Thus, sometimes your oldData will match your newData for a subschema. This can be resolved by giving it it's own pre-save route!
Thought this would be pretty straight forward, but my value is remaining the same (0).
What I'd like to do is increment my UnreadMessages field when the user receives a message they haven't read and then decrement it when they have. So I thought code like this would work:
var userHelper = new MongoHelper<User>();
//increment
userHelper.Collection.Update(Query.EQ("Id", userId.ToId()), Update.Inc("UnreadMessages", 1));
//decrement
userHelper.Collection.Update(Query.EQ("Id", userId.ToId()), Update.Inc("UnreadMessages", -1));
After running these no errors are thrown but the value doesn't change either. And no I'm not running one after the other as the code above could be interpreted :)
Update
Here's my helper class:
public class MongoHelper<T> : Sandbox.Services.IMongoHelper<T> where T : class
{
public MongoCollection<T> Collection { get; private set; }
public MongoHelper()
{
var con = new MongoConnectionStringBuilder(ConfigurationManager.ConnectionStrings["MongoDB"].ConnectionString);
var server = MongoServer.Create(con);
var db = server.GetDatabase(con.DatabaseName);
Collection = db.GetCollection<T>(typeof(T).Name.ToLower());
}
}
and thanks to Travis' answer I was able to pull this off:
MongoHelper<UserDocument> userHelper = new MongoHelper<UserDocument>();
var user = userHelper.Collection.FindAndModify(Query.EQ("Username", "a"), SortBy.Null, Update.Inc("MessageCount", 1), true).GetModifiedDocumentAs<UserDocument>();
Not sure what your helper does. Here is a working snippet I use:
var query = Query.And(Query.EQ("_id", keyName));
var sortBy = SortBy.Null;
var update = Update.Inc("KeyValue", adjustmentAmount);
var result = collection.FindAndModify(query, sortBy, update, true);
So, "query" finds the document, update does the increment, and FindAndModify puts them together and actually hits the database.
Greetings,
I'm trying to create a workflow using a ActivityBuilder, and then get the XAML.
This flow use a custom activity (WaitForInput) to handle bookmarks. This class inherits from NativeActivity.
I'm having a hard time finding a way to set 'Result' property of my WaitForInput activity, which expects a OutArgument.
Creating this same workflow by the VS designer, I could associate the boolean property 'MyResult' InOutArgument called 'wrapper'. Like this : [Wrapper.MyResult]
I would do this by code, and according to my research, I have to use DynamicActivityProperty.
The problem is that I don't know how to use my DynamicActivityProperty as OutArgument in this case.
This is an simplified version of the code:
var wrapper = new DynamicActivityProperty
{
Name = "Wrapper",
Type = typeof(InOutArgument<CommunicationWrapper>),
};
var activityBuilder = new ActivityBuilder();
activityBuilder.Properties.Add(wrapper);
var step1 = new FlowStep
{
//here's my problem
Action = new WaitForInput<bool> { BookmarkName = "step1", Result = ??? }
};
var flow = new Flowchart
{
StartNode = step1,
Nodes = { step1 }
};
I have founded a solution to my own problem
Result = new OutArgument<bool>(new VisualBasicReference<bool>
{ ExpressionText = "Wrapper.MyResult" }); }