I am trying to build a generic solution to a problem that is probably much more complicated than I realize.
For simplicity, consider that I have the following interface:
PagedResult<T> ToPagedResult<T>(this ICriteria, criteria, string sortName);
sortName is ideally a json-style path of access. E.g : Registration.Class.Curriculum.Description, where description is the property that we want to sort on.
In the case where I want to sort on a property of Class, I have been successful with the following:
ICriteria pageCriteria = criteria.CreateCriteria("Class", "Class").AddOrder(Order.Desc(sortName));
In this case, sortName might equal "Class.Name".
Now, is there a way where I could arbitrarily allow sorting on deeper children?
ICriteria pageCriteria = criteria
.CreateCriteria("Class", "Class")
.CreateCriteria("Class.Foo", "Foo")
.AddOrder(Order.Desc("Foo.Bar"));
Related
I have a node Country. I know that this node has some properties, but I don't know which. I mean, I know since I've take a look at model. Here is what I've found in documentation:
Country
name: String
iso_2_code: String
iso_3_code: String
region: String
sub.region: String
I know that if I run
MATCH (c:Country)
RETURN c.iso_2_code
I'll get result for one specific property. Is there a query that would as a result return me something like: name, iso_2_code, iso_3_code, region, sub.region?
If I didn't have access to the model how could I list all of the properties that are attached to some node type?
Answering more from a Cypher or openCypher perspective than for a specific implementation. Using the air-routes dataset. There are three things to consider.
Firstly if you know the properties you want, as you mentioned, you can just ask for them explicitly.
MATCH (a:airport {icao:'KDFW'})
RETURN a.city, a.desc
However, if you want all properties, but do not want to list them all, you can just do:
MATCH (a:airport {icao:'KDFW'})
RETURN properties(a)
If you just want the property keys:
MATCH (a:airport {icao:'KDFW'})
RETURN keys(properties(a))
Lastly, if you want the properties plus the label and ID information you can just do:
MATCH (a:airport {icao:'KDFW'})
RETURN a
In my SDN 4 project I have a following Cypher query(a part of query):
(entity)<-[:COMMENTED_ON]-(comg:CommentGroup)
for example I can get id of entity with a following Cypher function id(entity)
How to get entity name or class name ?
Use the labels function
match (entity)<-[:COMMENTED_ON]-(comg:CommentGroup) return id(entity), labels(entity)
For each row returned, you'll get the Neo4j id and array of labels.
Assuming your NodeEntity class labels match at least one of these labels, you can then iterate and load the appropriate class instance yourself.
Generally speaking you shouldn't need to do this however.
If (entity) is polymorphic, SDN/OGM will hydrate the correct objects for you. It pretty much does under the hood what I described above, but it also handles matching on interfaces, subclasses, etc.
Can someone tell me why in NHibernate mapping we can set access="field.camelcase", since we have access="field" and access="property"?
EDIT: my question is "why we can do this", not "what does it mean". I think this can be source of error for developper.
I guess you wonder what use field.camelcase have when we can do the same with just field? That's true, but that would give (NH) properties unintuive names when eg writing queries or reference the property from other mappings.
Let's say you have something you want to map using the field, eg
private string _name;
public string Name { get { return _name; } }
You sure can map the field using "field" but then you would have to write "_name" when eg writing HQL queries.
select a from Foo a where a._name = ...
If you instead using field.camelcase the data, the same query would look like
select a from Foo a where a.Name...
EDIT
I now saw you wrote "field.camelcase" but my answer is about "field.camelcase-underscore". The principles are the same and I guess you get the point ;)
the portion after the '.' is the so called naming strategy, that you should specify when the name you write in the hbm differ from the backing field. In the case of field.camelcase you are allowed to write CustomerName in the hbm, and NHibernate would look for a field with name customerName in the class. The reason for that is NHibernate not forcing you to choose a name convention to be compliant, NH will works with almost any naming convention.
There are cases where the properties are not suitable for NH to set values.
They may
have no setter at all
call validation on the data that is set, which is not used when loading from the database
do some other stuff that is only used when the value is changed by the business logic (eg. set other properties)
convert the value in some way, which would cause NH performing unnecessary updates.
Then you don't want NH to call the property setter. Instead of mapping the field, you still map the property, but tell NH to use the field when reading / writing the value. Roger has a good explanation why mapping the property is a good thing.
Using NHibernate, I need to be able to configure my application to sort a specific collection of entities exactly as needed.
The configurable sort:
can involve multiple properties
can specify the sorted properties in any order
can specify asc/desc on the sorted properties
can sort by custom properties (i.e. there is no corresponding SQL/C# property - it is calculated)
This functionality is inherited from an existing app where parts of the SQL are specified by an administrator and the SQL statement is built/executed dynamically.
Every time I try thinking through a solution I start getting in muddy waters with all kinds of alarms going off in my head regarding maintainability, performance, scalability, security, etc..
For example, I figure the admin can specify a comma delimited string like so:
"Date asc, FirstName asc, LastName desc"
I can split the string and go through a loop matching the property/sort pairings in a case statement and calling .AddOrder(Order.Asc("FirstName")) as necessary. But then, how do I handle custom properties? I could allow the user to specify SQL for calculating custom properties and then allow the user to sort on those like they would FirstName, but I'm seemingly back at dirty/kludge again.
Is there a clean/appropriate way to handle this requirement?
After much thought and a stroke of luck, I may have a solution.
public class CustomOrder : Order
{
private string customOrderSql;
public CustomOrder(string customOrderSql) : base("", true)
{
this.customOrderSql = customOrderSql;
}
public override NHibernate.SqlCommand.SqlString ToSqlString(
ICriteria criteria, ICriteriaQuery criteriaQuery)
{
return new NHibernate.SqlCommand.SqlString(this.customOrderSql);
}
}
I can pass a custom sort string to my repository where I add my CustomOrder as follows:
.AddOrder(new CustomOrder(customSort))
I still can't sort by custom properties but maybe I can get away with applying case statements in the order by clause. I'm still open for better suggestions if they exist.
I have an entity that has a string property called Tags. I would like to query this entity based upon if a certain string is located in Tags property.
So for example, I would have a function IList GetEntityByTag(string tag), this would return all Entity's that have the value of tag in their 'Tags' property.
I tried going through the ICriteria approach... Expression.In(PropertyName, Value) but this is the exact opposite. I need something like Expression.In(Value, PropertyName).
Perhaps IQuery would be a better strategy but I have not been able to find any type of HQL statment for Property CONTAINS 'abc'.
Any help or point of direction would be great thanks!
If you want to know if a tag is a substring in your Tags property, you might want to consider these tips:
You might want to convert both the string you are searching in and searching for to lowercase first. Expression.ilike does this for you. Score.
To find out if your search term is anywhere in the field, you can set the MatchMode parameter in the ilike function to MatchMode.ANYWHERE.
If, as you commented earlier,
let's say my property, 'Tags' =
a;b;c;d;e. I want to know if 'a'
exists in tags. Will
Expression.Like("Tags", "a") return
true?
If 'a;b;c;d;e' is a string, Expression.ilike( "Tags", "a", MatchMode.ANYWHERE ) will return true.
Do you mean Expression.Like(PropertyName, Value)?