i am facing an error while using contains function of LINQ query
following error occured
Contains is not supported, doing a substring match over a text field is a very
slow operation, and is not allowed using the Linq API.
The recommended method is to use full text search (mark the field as Analyzed and
use the Search() method to query it.
here is my query
query = from u in Session.Query<Article>() where u.Tags.Contains(tags) orderby u.CreationDate descending select
StartWith/EndsWith works fine but it is not full filling my requirements
As the error states, Contains won't work and you need to use Analyzed fields. You can start here: http://ravendb.net/docs/client-api/querying/static-indexes/configuring-index-options
Related
Errors in the use of Specification, returns one object out of 2 matching the search criteria, while builder returns the correct value.
springDatabaseItemRepository.findAll(builder.build(), pageable);
I'm looking for 3 conditions: 1 of which joins all queries and works. The other two are one simple query, the second is join connected using or. And after processing, only the results of join are returned to me.
I tried to change the processing and conditions, tried to read the documentation, but it didn't give me anything. Also, if you call join and a simple query separately, the results are returned correct.
I would like to create SQL query on some text field (not keyword) for example "name" field and send that query to elastic server.
my problem is that I need to use the standard SQL language (not the MATCH and QUERY operators which are specials for elastic SQL) of text fields.
when I tried to use JDBC driver or when I tried to use high-level-java-client with LIKE operatorI got the following error
"No keyword/multi-field defined exact matches for [name]; define one or use MATCH/QUERY instead"
I also tried to use the translate API of elasticsearch- but even there I couldn't use the "LIKE" operator on text fields only on keyword fields.
does anyone have any solution for me? I want to use the LIKE operator on text fields instead of the full text operators which are unique to elastic sql.
Please check the this documentation. they have clearly mentioned in document that it is not possible.
One significant difference between LIKE/RLIKE and the full-text search
predicates is that the former act on exact fields while the latter
also work on analyzed fields. If the field used with LIKE/RLIKE
doesn’t have an exact not-normalized sub-field (of keyword type)
Elasticsearch SQL will not be able to run the query. If the field is
either exact or has an exact sub-field, it will use it as is, or it
will automatically use the exact sub-field even if it wasn’t
explicitly specified in the statement.
If you still want to used text field then you need to enabled multi-field as mentioned here. or you can try out to enable fielddata on text field but i am not sure that it will work SQL or not.
I am using gorm to interact with a postgres database. I'm trying to ORDER BY a query that uses DISTINCT ON and this question documents how it's not that easy to do that. So I need to end up with a query in the form of
SELECT * FROM (<subquery>) ORDER BY column;
At first glance it looks like I need to use db.QueryExpr() to turn the query I have into an expression and build another query around it. However it doesn't seem gorm has an easy way to directly specify the FROM clause. I tried using db.Model(expr) or db.Table(fmt.Sprint(expr)) but Model seems to be completely ignored and fmt.Sprint(expr) doesn't return exactly what I thought. Expressions contain a few private variables. If I could turn the original query into a completely parsed string then I could use db.Table(query) but I'm not sure if I can generate the query as a string without running it.
If I have a fully built gorm query, how can I wrap it in another query to do the ORDER BY I'm trying to do?
If you want to write raw SQL (including one that has a SQL subquery) that will be executed and the results added to an object using gorm, you can use the .Raw() and .Scan() methods:
query := `
SELECT sub.*
FROM (<subquery>) sub
ORDER BY sub.column;`
db.Raw(query).Scan(&result)
You pass a pointer reference to an object to .Scan() that is structured like the resulting rows, very similarly to how you would use .First(). .Raw() can also have data added to the query using ? in the query and adding the values as comma separated inputs to the function:
query := `
SELECT sub.*
FROM (<subquery>) sub
WHERE
sub.column1 = ?
AND sub.column2 = ?
ORDER BY sub.column;`
db.Raw(query, val1, val2).Scan(&result)
For more information on how to use the SQL builder, .Raw(), and .Scan() take a look at the examples in the documentation: http://gorm.io/advanced.html#sql-builder
During prototyping I have imported a bunch of Facebook posts into a table in batches. After the first batch I did a bulk update to convert the "created_date" column from string to a native timestamp (using the handy r.ISO8601 function):
r.db('db').table('table').update({'created_date': r.ISO8601(r.row('created_date'))
On the second pass, when I try to repeat this update, the server throws an error because not all row fields are of type STRING (ie the ones previously converted), which is what ISO861 expects.
I've already tried to filter on r.row('created_date').typeOf() == "STRING" but got no matches. I can't find any other way to refer to the STRING type as an object rather than a literal string either.
I know that I could import these out and do the if/else logic in code, but I'm interested to understand if there's a native query that will filter out rows that match a certain type.
You have to use eq for comparing like this:
r.row('created_date').typeOf().eq("STRING")
Using == only works on some language support operator overrding.
Hi Experts
I have a special question About dynamic Linq to Sql.
Consider we want to search in a table according two fields*(LetterNo(string) and LetterDate(Datetime))*
.OK the problem is user can enter on of that fields or even both.
I searched in the internet and found "Linq.Dynamic" library in ScottGu weblog.but in that library if we want to use SqlParameter in exported command we should use #0 and param for that.problem is I don't know how many fields user entered.
I want use one query for that and no external tool like "Linq Kit PredicateBuilder".
If I create my query string Manually(and execute using ExecuteCommand) then I will abdicate SqlParameter and risk of Sql Injenction growing up.
How Can do that?
thanks
I suspect you are wanting to do something like the following:
IQueryable<Letter> query = context.Letters;
if (!string.IsNullOrEmpty(LetterNo))
query = query.Where(letter => letter.LetterNo == LetterNo);
If (LetterDate.HasValue)
query = query.Where(letter => letter.LetterDate == LetterDate);
When you execute query, it will combine the necessary expressions and issue a single query to the database based on the user's input.