Mercurial > urweb
comparison tests/tags.ur @ 2031:d11a7a9c4a73
New syntactic shorthand for antiquoting subqueries
| author | Adam Chlipala <adam@chlipala.net> |
|---|---|
| date | Wed, 25 Jun 2014 14:04:13 -0400 |
| parents | |
| children | 884673e5f7d5 |
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| 2030:6add6d00ef5f | 2031:d11a7a9c4a73 |
|---|---|
| 1 table images : { Id : int, Content : blob } | |
| 2 table tags : { Id : int, Tag : string } | |
| 3 | |
| 4 datatype mode = Present | Absent | |
| 5 type condition = { Tag : string, Mode : mode } | |
| 6 | |
| 7 type tag_query = sql_query [] [] [] [Id = int] | |
| 8 | |
| 9 fun addCondition (c : condition) (q : tag_query) : tag_query = | |
| 10 case c.Mode of | |
| 11 Present => (SELECT I.Id AS Id | |
| 12 FROM ({{q}}) AS I | |
| 13 JOIN tags ON tags.Id = I.Id AND tags.Tag = {[c.Tag]}) | |
| 14 | Absent => q | |
| 15 | |
| 16 fun withConditions (cs : list condition) : tag_query = | |
| 17 List.foldl addCondition (SELECT images.Id AS Id FROM images) cs | |
| 18 | |
| 19 fun main (cs : list condition) : transaction page = | |
| 20 x <- queryX (withConditions cs) (fn r => <xml><li>{[r.Id]}</li></xml>); | |
| 21 return <xml><body> | |
| 22 {x} | |
| 23 </body></xml> |