I have this armor table, that has three fields to identify individual designs: make, model and version.
I have to implement a search feature for our software, that lets a user search armors according to various criteria, among which their design.
Now, the users' idea of a design is a single string that contains make, model and version concatenated, so the entry is that single string. Let's say they want to look up the specifications for make FH, model TT, version 27, they'll think of (and type) "FHTT27".
We use an IQueryOver object, upon which we add successive conditions according to the criteria. For the design, our code is
z_quoQuery = z_quoQuery.And(armor => armor.make + armor.model + armor.version == z_strDesign);
Which raises an InvalidOperationException, "variable 'armor' of type 'IArmor' referenced from scope '', but it is not defined".
This is described as a bug here: https://github.com/mbdavid/LiteDB/issues/637
After a lot of trial and error, it seems that syntaxs that don't use the armor variable first raise that exception.
Obviously, I have to go another route at least for now, but after searching for some time I can't seem to find how. I thought of using something like
z_quoQuery = z_quoQuery.And(armor => armor.make == z_strDesign.SubString(0, 2).
And(armor => armor.model == z_strDesign.SubString(2, 2).
And(armor => armor.version == z_strDesign.SubString(4, 2);
Unfortunately, the fields are liable to have variable lengths. For instance, another set of values for make, model, and version might be, respectively, "NGI", "928", and "RX", that the code above would parse wrong. So I can't bypass the difficulty that way. Nor can I use a RegEx.
Neither can I make up a property in my Armor class that would concatenate all three properties, since it cannot be converted to SQL by NHibernate.
Has someone an idea of how to do it?
Maybe I should use an explicit SQL condition here, but how would it mix with other conditions?
It seems you can use Projections.Concat to solve your issue:
z_quoQuery = z_quoQuery.And(armor => Projections.Concat(armor.make, armor.model, armor.version) == z_strDesign);
Related
I'm having an issue getting a query to work.
I'm essentially trying to write something like the following SQL, with the literal 5 replaced with a variable:
SELECT *
FROM "my_table"
WHERE 5 BETWEEN "my_table"."minimum" AND "my_table"."maximum"
This is what I have at the moment:
MyModel.where(
Arel::Nodes::Between.new(
my_variable, (MyModel.arel_table[:minimum]).and(MyModel.arel_table[:maximum])
)
)
Please ignore the way I am using arel_table, the actual query has multiple joins and is more complex, but this is the most minimum reproducible example I have to demonstrate the problem.
The error, as in the subject of the question is as follows:
undefined method `and' for #<Arel::Attributes::Attribute:0x00007f55e15514f8>
and method is for Arel::Nodes::Node i.e. MyModel.arel_attribute[:name].eq(Arel::Nodes::Quoted.new('engineersmnky')) This is an Arel::Nodes::Equality and you can chain with and.
That being said you can construct an Arel::Nodes::And for yourself via
Arel::Nodes::And.new([left,right])
Then we can pass this to the Between class like so
Arel::Nodes::Between.new(
Arel::Nodes::Quoted.new(my_variable),
Arel::Nodes::And.new([
MyModel.arel_table[:minimum],
MyModel.arel_table[:maximum]])
)
The Arel::Nodes::Quoted (also: Arel::Nodes.build_quoted(arg)) is not needed in your case since your my_variable is an Integer which can be visited and will be treated as an Arel::Nodes::SqlLiteral but I find it best to let arel decide how to handle the quoting in case your my_variable ends up being some other un-visitable Object
There are other ways to create a Between and other ways to create an And depending on what objects you are dealing with.
between is a Arel::Predication and these predications are available to Arel::Nodes::Attribute objects e.g.
MyModel.arel_table[:minimum].between([1,6])
and as mentioned is available to Arel::Nodes::Node and instances of this class provides a convenience method (create_and) for creating an And so we could do the following:
Arel::Nodes::Node.new.create_and([
MyModel.arel_table[:minimum],
MyModel.arel_table[:maximum]])
There are a number of other ways to hack this functionality together by using other Arel classes but this should get you headed in the right direction.
Sometimes it is useful to assign a 'tag', which can be a simple string, to a matplotlib artist in order to later find it easily.
If we imagine a scenario where say plt.Line2D had a property called tag which can be retrieved using plt.Line2D.get_tag() it would be very easy to find it later in a complicated plot.
The only thing I can find that looks remotely similar is the group ID: for example line.set_gid() and line.get_gid(). I haven't found any good documentation on this. The only reference is this. Is this meant for such use as described above? Is it reserved for other operations in matplotlib?
This would be very useful for grouping different artists and then performing operations on them later, for example:
for line in ax.get_lines():
if line.get_tag() == 'group A'
line.set_color('red')
# or whatever other operation
Does such a thing exist?
You can use the gid for such purposes. The only side-effect is that those names will appear in a saved svg file as the gid tag.
Alternatively you can assign any attribute to a python object.
line, = plt.plot(...)
line.myid = "group A"
just make sure not to use any existing attribute in such case.
I'm fairly certain after years of searching that this is not possible, but I'll ask anyway.
The question is whether it's possible to use a dynamic variable in an operation when you don't know the field name. For example, I have a data structure that contains a few hundred fields. The operator selects one of those fields and the program needs to know what data resides in the field from the data structure passed. So we'll say that there are 100 fields, and field50 is what the operator chose to operate on. The program would be passed in the field name (i.e. field50) in the FLDNAM variable. The program would read something like this the normal way:
/free
if field50 = 'XXX'
// do something
endif;
/end-free
The problem is that I would have to code this 100 times for every operation. For example:
/free
if fldnam = 'field1';
// do something
elseif fldnam = 'field2';
// do something
..
elseif fldnam = 'field50';
// do something
endif;
Is there any possible way of performing an operation on a field not yet known? (i.e. IF FLDNAM(pointer data) = 'XXX' then do something)
If the data structure is externally-described and you know what file it comes from, you could use the QUSLFLD API to find out the offset, length, and type of the field in the data structure, and then use substring to get the data and then use other calculations to get the value, depending on the data type.
Simple answer, no.
RPG's simply not designed for that. Few languages are.
You may want to look at scripting languages. Perl for instance, can evaluate on the fly. REXX, which comes installed on the IBM i, has an INTERPRET keyword.
REXX Reference manual
Following is a Node we having in DB
P:Person { name:"xxx", skill:"Java" }
and after awhile, we would like to change the Skill to skill array, is it possible?
P:Person { name:"xxx", skill:["Java", "Javascript"] }
Which Cypher query should I use?
If you have a single skill value in skill, then just do
MATCH (p:Person)
WHERE HAS (p.skill)
SET p.skill=[p.skill]
If there are multiple values you need to convert to an array such as P:Person { name:"xxx", skill:"Java","JavaScript" } then this should work:
MATCH (p:P)
SET p.skill= split(p.skill,",")
In fact, I think your real problem here is not how to get an array property in a node, but how to store it. Your data model is wrong in my opinion, storign data as array in neo4j is not common, since you have relations to store multiple skills (in your example).
How to create your data model
With your question, I can already see that you have one User, and one User can have 1..n skills.
I guess that one day (maybe tomorrow) you will need to know which users are able to use Java, C++, PHP, and every othre skills.
So, Here you can already see that every skill should have its own node.
What is the correct model in this case?
I think that, still with only what you said in question, you should have something like this:
(:Person{name:"Foo"})-[:KNOWS]->(:Skill{name:"Bar"})
using such a data model, you can get every Skill known by a Person using this query:
MATCH (:Person{name:"Foo"})-[:KNOWS]->(skill:Skill)
RETURN skill //or skill.name if you just want the name
and you can also get every Person who knows a Skill using this:
MATCH (:Skill{name:"Bar"})<-[:KNOWS]-(person)
RETURN person //Or person.name if you just want the name
Keep in mind
Storing array values in properties should be the last option when you are using neo4j.
If a property can be found in multiple nodes, having the same value, you can create a node to store it, then you will be able to link it the other nodes using relations, and finding every node having the property X = Y will be easier.
Consider the case where a certain mocked function is expected to be called several times, each time with a different value in a certain parameter. I would like to validate that the function was indeed called once and only once per value in a certain list of values (e.g. 1,2,5).
On the other hand, I would like to refrain from defining a sequence as that would dictate a certain order, which is an implementation detail I would like to keep free.
Is there some kind of matcher, or other solution for this case?
I'm not sure if this influences the solution in any way but I do intend to use WillOnce(Return(x)) with a different x per value in the list above.
By default gMock expectations can be satisfied in any order (precisely for the reason you mention -- so you don't over specify your tests).
In your case, you just want something like:
EXPECT_CALL(foo, DoThis(1));
EXPECT_CALL(foo, DoThis(2));
EXPECT_CALL(foo, DoThis(5));
And something like:
foo.DoThis(5);
foo.DoThis(1);
foo.DoThis(2);
Would satisfy those expectations.
(Aside: If you did want to constrain the order, you should use InSequence: https://github.com/google/googletest/blob/master/googlemock/docs/cook_book.md#expecting-ordered-calls-orderedcalls)
If you expect a function, DoThing, to be called with many different parameters, you can use the following pattern:
for (auto const param : {1, 2, 3, 7, -1, 2}){
EXPECT_CALL(foo, DoThing(param));
}
This is particularly helpful if your EXPECT_CALL includes many parameters, of which only one is changing, or if your EXPECT_CALL includes many Actions to be repeated.