Django - Making a SQL query on a many to many relationship with PostgreSQL Inner Join -

-

i looking perticular raw sql query using inner join.

i have models:

class ezmap(models.model):     layers = models.manytomanyfield(shapefile, verbose_name='layers display', null=true, blank=true)   class shapefile(models.model):     filename = models.charfield(max_length=255)   class feature(models.model):     shapefile = models.foreignkey(shapefile)

i make sql query valid postgresql one:

select id "table_feature" where' shapefile_ezmap_id = 1 ;

but dont know how use inner join filter features shapefile belongs related particular ezmap object

something this:

try:     id = feature.objects.get(shapefile__ezmap__id=1).id except feature.doesnotexist:     id = 0 # or other action when no result found

you need use filter (instead of get) if want deal multiple feature results.


Comments

Post a Comment

Popular posts from this blog

c# - must be a non-abstract type with a public parameterless constructor in redis -

-
when save object, got below error must non-abstract type public parameterless constructor in order use parameter 't' in generic type or method 'servicestack.redis.redisclient.store<t>(t) redisclass.getinstnace().store(msg); // error here redisclass.getinstnace().save(); as third party's class, can not edit how save object? could create wrapper around third party object call constructor, store wrapper? e.g. public class mywrapper { public thirdpartyobject thirdpartyinstance { get; set; } public mywrapper() { thirdpartyinstance = new thirdpartyobject("constructors"); } }
Read more

c# - ReportViewer control - axd url -

-
i've embedded microsoft.reporting.webforms.reportviewer control in aspx. site works on mysite.com. when try exmple export report, there new black window opened address mysite.com/reserved.reportviewerwebcontrol.axd... it's working fine. but.. pass axd via proxy. mean, i'd force export use url myproxy.mysite.com/reserved.reportviewerwebcontrol.axd... redirect request mysite.com/reserved.reportviewerwebcontrol.axd... i've noticed, link build within js (that inlcuded in axd): exportreport: function(format) { if (this.exporturlbase == null) return false; window.open(this.exporturlbase + encodeuricomponent(format), "_blank"); return true; }, the url axd stored in exporturlbase . how can change proxy serwer url? it possible modify exporturlbase field in javascript. report stored in placeholder somewhere on page, once found can create call _getinternalviewer() function on gain access exporturlbase. have @ following code: ...
Read more

time series - R growth rate calculation week over week on daily timeseries data -

-
i'm trying calculate w/w growth rates entirely in r. use excel, or preprocess ruby, that's not point. data.frame example date gpv type 1 2013-04-01 12900 office 2 2013-04-02 16232 office 3 2013-04-03 10035 office i want factored 'type' , need wrap date type column weeks. , calculate week on week growth. i think need ddply group week - custom function determines if date in given week or not? then, after that, use diff , find growth b/w weeks divided previous week. then i'll plot week/week growths, or use data.frame export it. this closed had same useful ideas. update: answer ggplot: all same below, use instead of plot ggplot(data.frame(week=seq(length(gr)), gr), aes(x=week,y=gr*100)) + geom_point() + geom_smooth(method='loess') + coord_cartesian(xlim = c(.95, 10.05)) + scale_x_discrete() + ggtitle('week on week growth rate, apr 1') + ylab('growth rate %') (old, correct answer using plot) w...
Read more