I have found that I need to specify predicate types as int in my schema or else numbers get stored as type float:
MyNumericalProperty: int #index(int) .
I have facets that are also numbers, and in the JSON returned from dgraph they appear like so:
"MyProperty|MyPropertyFacet":1.000000
Is there a way to add this to the schema as an int?
Nope, facets are not first-class citizen. So you can't define it. If you have a good use case, maybe opening an issue to request this feature would be interesting.
Related
Is there a way to actually define the type of a query-parameter? Atm, I can only define the name and if the parameter is required:
f.e. I would like to define arrays or numbers as query-paramters.
You can use multivalued parameter for array
GET resource?id=1&id=2&id=3
If you share your usecase why you need number or bigdecimal or int will help you to find solution.
I've seen code snippets like these:
export interface IUser {
email?: string;
firstName?: string;
lastName?: string;
}
But why are the variable names suffixed by a question mark? This snippet is part of an example of using mongodb with Typescript.
The answer is probably somewhere out there but I seem to be using the wrong keywords since I can't find it.
In TypeScript, <name>?: <typename> a shorthand for <name>: <typename> | undefined.
This indicates to the type system that a symbol may contain a value of the indicated type or it may contain the value undefined (which is like null).
This is important when the (new in TypeScript 2) --strictNullChecks option is enabled. The documentation on Null- and undefined-aware types option is probably where you should start to understand why this is useful.
It means they can be there but dont have to be. It allows for optional field names. It can be quite common to use.
An example use is allowing users on a website to have an optional display name.
If I am not mistaked, its to indicate that its optional, that means that it can be null.
I am porting a Clojure program to Swift. Being a dynamically typed language, it is easy to throw different values together like this:
(def settings {:total-gens 5
:name "Incredible Program"
:options [:a :b :c :d :e]
:final-comment "Hope you had a good time."})
I pass settings maps like this around in the program, and I wanted to have a fairly similar process in Swift.
Right away, I feel like I am fighting the type system and I'm wondering what is the most elegant way to do this.
Here are two options that were recommended to me, both of which seem verbose or strange:
1) First, make an enum type of all possible settings value types. Then, create a dictionary of String: SettingsEnumType. Every time I need to add a new type of value to my dictionary, I first need to change the enum definition, and then change the actual dictionary.
2) Instead, create an empty protocol with no requirements. Then extend values like Int, String, etc to adopt this protocol, even though it is really a "dummy" protocol. Then make my settings dictionary String : SettingsProtocol so I can add whatever type I want in there (after first extending the type).
Both of these options feel weird to me, like I'm trying to circumvent the type system rather than have it work for me. The second option is frankly silly, but would no doubt work as needed.
Are there any other possibilities for doing something like this? Additionally, would the String type be the only obvious type for the keys in a settings dictionary? In this case, Clojure has again spoiled me with the useful keyword type that simultaneously acts as a look-up function in addition to a value type.
Any advice/pointers appreciated as I consider this new language.
After referring to Array with string and number answer, I believe you can create a Heterogeneous Dictionary with below Syntax:
let heteroDict = Dictionary<Any, Any>()
Can you try this one?
Let's say I get two instances in my code and I don't know their types. How to check it?
If in Java, I can use this code:
a.getClass() == b.getClass()
But in Dart, I can't find similar methods. Although there is the dart:mirrors providing reflect(instance) function, which may let me do it, but I'm not sure if that's a correct solution since it looks complicated.
a.runtimeType == b.runtimeType
I think dart:mirrors (reflection) API helps you. Look at this page :
http://blog.dartwatch.com/2012/06/dartmirrors-reflection-api-is-on-way.html
Also you can look this question(with runtime solution)
How do I get the qualified name from a Type instance, in Dart?
if you want to compare a and b you can use
if(a.runtimeType == b.runtimeType);
but if you want to confirm that a is the type you want you need to do this
if(a.runtimeType.toString()=="DivElement");//a is a div for instance
because runtimeType's value is not a string
I am building a highly generic query mechanism on top of the JPA Criteria. I get as input an XML describing the query, something like this:
<?xml version='1.0' encoding='UTF-8' standalone='yes'?>
<Criteria xmlns='criteria' maxResults='2'>
<Expression>
<CompareRestriction propertyType='Date' operator='GREATER_THAN_OR_EQUALS' propertyName='deliveryDate'>2010-07-02</CompareRestriction>
<CompareRestriction propertyType='Float' operator='GREATER_THAN_OR_EQUALS' propertyName='weight'>10f</CompareRestriction>
<Restriction operator='NOT_NULL' propertyName='maxDiameter'/>
<LogicalExpression operator='OR'>
<LeftHandSideCompare propertyType="Integer" operator="EQUALS" propertyName="weight">31</LeftHandSideCompare>
<RightHandSide operator='NOT_NULL' propertyName='lastChangedDate'/>
</LogicalExpression>
<LogicalExpression operator='OR'>
<LeftHandSideCompare propertyType="Integer" operator="EQUALS" propertyName="weight">31</LeftHandSideCompare>
<RightHandSide operator='NOT_NULL' propertyName='lastChangedDate'/>
</LogicalExpression>
</Expression>
<Order propertyName='deliveryDate' type='DESC'/>
</Criteria>
and I parse this thing and build the corresponding criteria. Currently I am facing a problem with it comes to comparison operators (<,>,<=,=>) as I deal with different numerical types: I have fields with Float, Integer or Long value. So when I am mapping I do something like this:
switch (leftHandSideCompareRestriction.getOperator().value()) {
...
case "LESS_THAN" : innerPredicates.add(criteriaBuilder.gt(rootQuery.<Number>get(propName), NumberUtils.createNumber((value))));
case "LESS_THAN_OR_EQUALS" : innerPredicates.add(criteriaBuilder.gt(rootQuery.<Number>get(propName), NumberUtils.createNumber(value)));
...
}
The NumberUtils is the apache commons NumberUtils utility class
that returns a numerical type based on the input provided (Float, Integer, Long or Double). Now I need a mechanism to provide the type also for the
rootQuery<T>.get(propName)
at runtime, otherwise the JPA is complaining that I provided a Float instead of a Integer or the other way around. I tried several things and now I kind of ran out of ideas. I would highly appreciate and thoughts, ideas, suggestions about how to accomplish this in a robust fashion.
I seems that initially I missed something - I am not sure how. There some kind of issue in a different part. So, doing the query like this: it will work for sure. I tried with the following types:
Integer
Float
And it worked as expected for the following operations: >,<, <=, =>. In conclusion using Number and the NumberUtils fixes this issue in quite an elegant manner, as the appropriate type is created by the NumberUtils and JPA takes the top of the hierarchy for Number.