Scalar-Value Function about arangoclient.net HOT 6 CLOSED

@sithwin if by Scalar you mean to return attributes of a document then you should use LINQ for this:

Assume you want to return ResourceName attribute of Resource collection:

string resourceName = db.Query<Resource>()
               // with Where you could apply any condition
                .Select(r => r.ResourceName)
                .First();

If you want to check if a document has a attribute or not you could:

bool hasResourceName = db.Query<Resource>()
                .Select(r => AQL.Has(r, "ResourceName"))
                .First();

from arangoclient.net.

Hi @ra0o0f , thanks for your quick reply.

Any performance different between:

            `bool has = _arangoDb.Query<CmsContentTypeView>()
                .Where( r => r.Key == Id.ToString())
                .Select(r => AQL.Has(r, "Id"))
                .First();`

And

if (_arangoDb.Document<Resource>(Id) == null)

I think, first query returns only Id and Second has whole object.

Please advice!

Thanks.

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@sithwin first query doe not return the id, it checks if document has Id attribute or not. if you want to return it use:

string resourceName = db.Query<CmsContentTypeView>()
                .Where( r => r.Key == Id.ToString())
                .Select(r => r.Key)
                .First();

About the performance you are right, _arangoDb.Document will return the whole object and therefore it's slower.

@sithwin i'm not sure if i understand completely what you want to achieve, if you can explain it, i can show how to query it

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Hi @ra0o0f ,

Firstly, I would like to make use of arangoDB key for better performance.
Secondly, I just want to check the again whether the data is successfully inserted. On the other hand, I created custom arrangoDb key before I inserted into database.

Right now, I used
if (_arangoDb.Document<Resource>(Id) == null) to check the data is inserted or not. However, it returns the whole object. It is expensive.

I just want to check with the key whether it is exist or not..

I think, this is less expensive than my above "if" statement.
bool has = _arangoDb.Query<Resource>() .Where(r => r.Key == Id.ToString()) .Select(r => AQL.Has(r, r.Key)) .First();

Please advice what should be the best approach.

Thanks.

from arangoclient.net.

@sithwin now i understand what you want to do.

for checking if a document exists or not with LINQ(AQL), there is no need for AQL.Has since it checks for attributes existence not the document, just get count and check if its zero or not

var count = db.Query<Resource>()
                   .Where(r => r.Key == Id.ToString())
                    .Count();

if(count!=0)
  // then exists

There is another way to check for the document existence without loading it. it's not implemented yet. i will inform you as soon as its done

@sithwin note that ArangoDB has also Upsert command which can insert/update a document if it exists or not in one request. this is usefull if you care about performance and consistency

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Hi @ra0o0f ,

For now on, .Count() can be solved my requirement.

Pls be inform once document existence method is available.

Thanks a lot!

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