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https://issues.apache.org/jira/browse/GROOVY-8258?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Paul King closed GROOVY-8258.
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> [GEP] Create a LINQ-like DSL (basic cases)
> ------------------------------------------
>
> Key: GROOVY-8258
> URL: https://issues.apache.org/jira/browse/GROOVY-8258
> Project: Groovy
> Issue Type: New Feature
> Reporter: Daniel Sun
> Assignee: Daniel Sun
> Priority: Major
> Fix For: 4.0.0-alpha-2
>
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> h2. *Ⅰ. Introduction*
> GINQ DSL is an alternative solution of GINQ, it is a simplified version of
> GINQ(GROOVY-9159) and will be implemented as a module "groovy-ginq".
> GINQ DSL is wrapped with:
> {code:java}
> GQ {
> // GINQ code
> }
> {code}
> *NOTE:*
> * The simplest GINQ *MUST* consist of *ONE* {{from}} clause and *ONE*
> {{select}} clause, which looks like:
> {code:java}
> from n in [1, 2, 3]
> select n
> {code}
> * Currently supports the following clauses:
> {code:java}
> ginq
> |__ from
> |__ [innerjoin/leftjoin/rightjoin/fulljoin/crossjoin]*
> | |__ on
> |__ [where]
> |__ [groupby]
> | |__ [having]
> |__ [orderby]
> |__ [limit]
> |__ select
>
> (Note: [ ] means optional)
> {code}
> h2. *Ⅱ. Sample code related to GROOVY-9159*
> h3. 1. Filtering
> h4. 1.1
> {code:java}
> from p in persons
> where p.age > 15 && p.age <= 35
> select p.name
> {code}
> h4. 1.2
> {code:java}
> from p in persons
> where p.age > 15 && p.age <= 35
> select p
> {code}
> h4. 1.3
> {code:java}
> from t in numbers
> where t <= 2
> select t
> {code}
> h3. 2. Joining
> h4. 2.1
> {code:java}
> from p in persons
> innerjoin c in cities on p.city.name == c.name // putting `on` clause in the
> same line with `innerjoin` is recommended code style
> select p.name, c.name
> {code}
> h4. 2.2
> {code:java}
> from p in persons
> innerjoin c in cities on p.city == c
> select p.name
> {code}
> h4. 2.3
> {code:java}
> from p in persons
> leftjoin c in cities on p.city.name == c.name // same with left outer join
> select p.name, c.name
> {code}
> h4. 2.4
> {code:java}
> from p in persons
> rightjoin c in cities on p.city.name == c.name // same with right outer join
> select p.name, c.name
> {code}
> h3. 3. Projection
> h4. 3.1
> {code:java}
> from p in persons
> select p.name
> {code}
> h4. 3.2
> {code:java}
> from p in persons
> select p.name, p.age
> {code}
> h4. 3.3
> {code:java}
> from p in persons
> select [name: p.name, age: p.age]
> {code}
> h4. 3.4
> {code:java}
> from p in persons
> select new Person(name: p.name, age: p.age)
> {code}
> h4. 3.5
> {code:java}
> from p in persons
> select p
> {code}
> h3. 4. Grouping
> h4. 4.1
> {code:java}
> from p in persons
> groupby p.gender
> select p.gender, max(p.age)
> {code}
> h3. 5. Having
> h4. 5.1
> {code:java}
> from p in persons
> groupby p.gender
> having p.gender == 'Male'
> select p.gender, max(p.age)
> {code}
> h3. 6. Sorting
> h4. 6.1
> {code:java}
> from p in persons
> orderby p.age
> select p.name
> {code}
> h4. 6.2
> {code:java}
> from p in persons
> orderby p.age in desc // "`in` order" means sorting
> select p.name
> {code}
> h4. 6.3
> {code:java}
> from p in persons
> orderby p.age in desc, p.name in asc // asc is optional
> select p.name
> {code}
> h3. 7. Pagination
> h4. 7.1
> {code:java}
> from n in numbers
> limit 2, 5
> select n
> {code}
> h4. 7.2
> {code:java}
> from n in numbers
> limit 5
> select n
> {code}
> h3. 8. Nested Queries
> h4. 8.1
> {code:java}
> from v in (
> from n in numbers
> where n <= 5
> select n
> )
> limit 2, 5
> select v
> {code}
> h4. Advanced cases could be found at GROOVY-9806
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