mongodb - Sort by subdocuments fields in mongo -


given following collection:

[     {         name: user1         metadata: [             {k:"score", v: 5},             {k:"other", v: 10}         ]     },     {         name: user2         metadata: [             {k:"score", v: 1},             {k:"other", v: 1}         ]     },     {         name: user3         metadata: [             {k:"score", v: 2},             {k:"other", v: 0}         ]     } ]

how can sort these items "score"? can sort metadata.v field, not sure how consider "v" values subdocuments match "k":"score"

the expected output be:

[     {         name: user2         metadata: [             {k:"score", v: 1},             {k:"other", v: 1}         ]     },     {         name: user3         metadata: [             {k:"score", v: 2},             {k:"other", v: 0}         ]     },     {         name: user1         metadata: [             {k:"score", v: 5},             {k:"other", v: 10}         ]     } ]

an alternative solution this, whereby final projection stage optional if can live additional scoredata property. 

db.yourcollection.aggregate([     {         $project: {             name: 1,             metadata: 1,             scoredata: {                 $filter: {                     input: '$metadata',                     as: 'metadoc',                     cond: {                         $eq: [ '$$metadoc.k', 'score' ]                     }                 }             }         }     },     {         $sort: {             scoredata: 1         }     },     {         $project: {             name: 1,             metadata: 1                     }     } ])

output looks 

/* 1 */ {     "_id" : objectid("5796387b3360e0a2e9dd9fc3"),     "name" : "user2",     "metadata" : [          {             "k" : "score",             "v" : 1         },          {             "k" : "other",             "v" : 1         }     ] }  /* 2 */ {     "_id" : objectid("5796387b3360e0a2e9dd9fc4"),     "name" : "user3",     "metadata" : [          {             "k" : "score",             "v" : 2         },          {             "k" : "other",             "v" : 0         }     ] }  /* 3 */ {     "_id" : objectid("5796387b3360e0a2e9dd9fc2"),     "name" : "user1",     "metadata" : [          {             "k" : "score",             "v" : 5         },          {             "k" : "other",             "v" : 10         }     ] }

Comments

Post a Comment

Popular posts from this blog

jOOQ update returning clause with Oracle -

according http://www.jooq.org/doc/3.8/manual/sql-building/sql-statements/update-statement/ jooq doesn't support returning clause in update statements databases except firebird , postgres. does know, still correct oracle jooq? according oracle's documentation, oracle db supports returning clase delete, insert, or update statements. incorrect manual you're right - manual wrong , should fixed: https://github.com/jooq/jooq/issues/5470 single row update returning jooq 3.8 added support single row update .. returning statements. internally, uses callablestatement , pl/sql block of form: begin update "my_table" set "my_table"."column" = 'xyz' "my_table"."id" = 1 returning "my_table"."id", "my_table"."column" ?, ?; ? := sql%rowcount; end; the relevant issue is: https://github.com/jooq/jooq/issues/5190 multi row update returning a...
Read more

java - Warning equals/hashCode on @Data annotation lombok with inheritance -

i have entity inherits other. on other hand, i'm using lombok project reduce boilerplate code, put @data annotation. annotation @data inheritance produces next warning: generating equals/hashcode implementation without call superclass, though class not extend java.lang.object. if intentional, add '@equalsandhashcode(callsuper=false)' type. is advisable add annotation @equalsandhashcode (callsuper = true) or @equalsandhashcode (callsuper = false) ? if not added, 1 callsuper=false or callsuper=true ? the default value false . 1 if don't specify , ignore warning. yes, recommended add @equalsandhashcode annotation on @data annotated classes extend else object. cannot tell if need true or false , depends on class hierarchy, , need examined on case-by-case basis. however, project or package, can configure in lombok.config call super methods if not direct subclass of object. lombok.equalsandhashcode.callsuper = call for configuration system ...
Read more

java - BasicPathUsageException: Cannot join to attribute of basic type -

i using java 8 jpa (hibernate 5.2.1). have clause works perfectly, until introduce clause make use foreign key table values too. i getting following error: basicpathusageexception: cannot join attribute of basic type i think problem related fact have join table, , not sure how create join using join table. employee - employee_category - category model (employee.java): @manytomany(cascade = cascadetype.all, fetch=fetchtype.eager) @jointable ( name="employee_category", joincolumns={ @joincolumn(name="emp_id", referencedcolumnname="id") }, inversejoincolumns={ @joincolumn(name="cat_id", referencedcolumnname="id") } ) private set<category> categories; model (category.java): @id private string id; jpa when introduce following code, fails error above (i think problem new piece of code): join<t, category> category = from.join("id"); predicates.add(criteriabuilder.like(category....
Read more