Comment utiliser la clause Where pour correspondre à la condition DateTime

La requête ci-dessous fonctionne correctement pour moi jusqu'à ce que j'applique Where condition pour Hour avec l'attribut Id = '06/02/2009 12:00CDT'.Comment utiliser la clause Where pour correspondre à la condition DateTime

Je dois obtenir la température maximale pour la date du jour seulement, et je ne suis pas en mesure d'utiliser la condition Where dans le champ de date. Des idées sur ce que je fais mal?

Dim document = XDocument.Load("c:\meridian.xml") 
Dim wind_gusts = From county In document.Root.Elements("county") Where county.Attribute("name") = "Adams" _ 
From hour In county.Elements("hour") Where county.Element("hour").Attribute("id").Value = "06/02/2009 13:00CDT" _ 
From wind_gust In hour.Elements("wind_gust") _ 
Select CInt(wind_gust) '< DateTime.Parse("06/03/2009") _ 
'DateTime.Parse(county.Element("hour" + ID).Attribute("id")) 
'Dim wind_gust_value = wind_gusts.Max() 

For Each m In wind_gusts 
    Response.Write(m.ToString()) 
Next

Ci-dessous le xml:

<?xml version="1.0" ?> 
- <forecasts> 
    <issued>06/02/2009 12:00CDT</issued> 
- <county name="Adair"> 
- <hour id="06/02/2009 12:00CDT"> 
    <air_temp>61</air_temp> 
    <cloud_cover>overcast</cloud_cover> 
    <dew_point>59</dew_point> 
    <precip_prob>90</precip_prob> 
    <precip_rate>0.12</precip_rate> 
    <precip_type>rain</precip_type> 
    <snow_rate>0.0</snow_rate> 
    <wind_direction>NE</wind_direction> 
    <wind_speed>12</wind_speed> 
    <dew_point_confidence>-3/+3</dew_point_confidence> 
    <road_temp>64</road_temp> 
    <road_frost_prob>0</road_frost_prob> 
    <road_potential_evap_rate>429</road_potential_evap_rate> 
    <road_temp_confidence>-3/+2</road_temp_confidence> 
    <dew_point_confidence>-3/+3</dew_point_confidence> 
    <bridge_temp>63</bridge_temp> 
    <bridge_temp_confidence>-4/+2</bridge_temp_confidence> 
    <bridge_frost>NO</bridge_frost> 
    </hour> 
+ <hour id="06/02/2009 13:00CDT"> 
    <air_temp>61</air_temp> 
    <cloud_cover>overcast</cloud_cover> 
    <dew_point>60</dew_point> 
    <precip_prob>70</precip_prob> 
    <precip_rate>0.01</precip_rate> 
    <precip_type>rain</precip_type> 
    <snow_rate>0.0</snow_rate> 
    <wind_direction>ENE</wind_direction> 
    <wind_speed>10</wind_speed> 
    <dew_point_confidence>-3/+3</dew_point_confidence> 
    <road_temp>65</road_temp> 
    <road_frost_prob>0</road_frost_prob> 
    <road_potential_evap_rate>411</road_potential_evap_rate> 
    <road_temp_confidence>-3/+2</road_temp_confidence> 
    <dew_point_confidence>-3/+3</dew_point_confidence> 
    <bridge_temp>64</bridge_temp> 
    <bridge_temp_confidence>-4/+1</bridge_temp_confidence> 
    <bridge_frost>NO</bridge_frost> 
    </hour> 
+ <hour id="06/02/2009 14:00CDT"> 
    <air_temp>64</air_temp> 
    <cloud_cover>overcast</cloud_cover> 
    <dew_point>60</dew_point> 
    <precip_prob>60</precip_prob> 
    <precip_rate>trace</precip_rate> 
    <precip_type>rain</precip_type> 
    <snow_rate>0.0</snow_rate> 
    <wind_direction>NE</wind_direction> 
    <wind_speed>12</wind_speed> 
    <dew_point_confidence>-3/+3</dew_point_confidence> 
    <road_temp>65</road_temp> 
    <road_frost_prob>0</road_frost_prob> 
    <road_potential_evap_rate>560</road_potential_evap_rate> 
    <road_temp_confidence>-3/+2</road_temp_confidence> 
    <dew_point_confidence>-3/+3</dew_point_confidence> 
    <bridge_temp>65</bridge_temp> 
    <bridge_temp_confidence>-3/+2</bridge_temp_confidence> 
    <bridge_frost>NO</bridge_frost> 
    </hour> 
+ <hour id="06/02/2009 15:00CDT"> 
    <air_temp>63</air_temp> 
    <cloud_cover>overcast</cloud_cover> 
    <dew_point>59</dew_point> 
    <precip_prob>50</precip_prob> 
    <precip_rate>trace</precip_rate> 
    <precip_type>rain</precip_type> 
    <snow_rate>0.0</snow_rate> 
    <wind_direction>NE</wind_direction> 
    <wind_gust>15</wind_gust> 
    <wind_speed>12</wind_speed> 
    <dew_point_confidence>-3/+3</dew_point_confidence> 
    <road_temp>63</road_temp> 
    <road_frost_prob>0</road_frost_prob> 
    <road_potential_evap_rate>397</road_potential_evap_rate> 
    <road_temp_confidence>-4/+3</road_temp_confidence> 
    <dew_point_confidence>-3/+3</dew_point_confidence> 
    <bridge_temp>63</bridge_temp> 
    <bridge_temp_confidence>-3/+2</bridge_temp_confidence> 
    <bridge_frost>NO</bridge_frost> 
    </hour> 
+ <hour id="06/02/2009 16:00CDT"> 
    <air_temp>64</air_temp> 
    <cloud_cover>overcast</cloud_cover> 
    <dew_point>57</dew_point> 
    <precip_prob>40</precip_prob> 
    <precip_rate>trace</precip_rate> 
    <precip_type>rain</precip_type> 
    <snow_rate>0.0</snow_rate> 
    <wind_direction>ENE</wind_direction> 
    <wind_gust>16</wind_gust> 
    <wind_speed>11</wind_speed> 
    <dew_point_confidence>-3/+3</dew_point_confidence> 
    <road_temp>62</road_temp> 
    <road_frost_prob>0</road_frost_prob> 
    <road_potential_evap_rate>400</road_potential_evap_rate> 
    <road_temp_confidence>-3/+3</road_temp_confidence> 
    <dew_point_confidence>-3/+3</dew_point_confidence> 
    <bridge_temp>61</bridge_temp> 
    <bridge_temp_confidence>-4/+2</bridge_temp_confidence> 
    <bridge_frost>NO</bridge_frost> 
    </hour> 
+ <hour id="06/02/2009 17:00CDT"> 
    <air_temp>63</air_temp> 
    <cloud_cover>overcast</cloud_cover> 
    <dew_point>56</dew_point> 
    <precip_prob>30</precip_prob> 
    <precip_rate>trace</precip_rate> 
    <precip_type>rain</precip_type> 
    <snow_rate>0.0</snow_rate> 
    <wind_direction>ENE</wind_direction> 
    <wind_gust>15</wind_gust> 
    <wind_speed>10</wind_speed> 
    <dew_point_confidence>-3/+3</dew_point_confidence> 
    <road_temp>61</road_temp> 
    <road_frost_prob>0</road_frost_prob> 
    <road_potential_evap_rate>344</road_potential_evap_rate> 
    <road_temp_confidence>-3/+3</road_temp_confidence> 
    <dew_point_confidence>-3/+3</dew_point_confidence> 
    <bridge_temp>60</bridge_temp> 
    <bridge_temp_confidence>-4/+2</bridge_temp_confidence> 
    <bridge_frost>NO</bridge_frost> 
    </hour> 
+ <hour id="06/02/2009 18:00CDT"> 
    <air_temp>62</air_temp> 
    <cloud_cover>mostly cloudy</cloud_cover> 
    <dew_point>54</dew_point> 
    <precip_prob>20</precip_prob> 
    <precip_rate>trace</precip_rate> 
    <precip_type>rain</precip_type> 
    <snow_rate>0.0</snow_rate> 
    <wind_direction>ENE</wind_direction> 
    <wind_speed>10</wind_speed> 
    <dew_point_confidence>-3/+4</dew_point_confidence> 
    <road_temp>61</road_temp> 
    <road_frost_prob>0</road_frost_prob> 
    <road_potential_evap_rate>530</road_potential_evap_rate> 
    <road_temp_confidence>-3/+3</road_temp_confidence> 
    <dew_point_confidence>-3/+4</dew_point_confidence> 
    <bridge_temp>61</bridge_temp> 
    <bridge_temp_confidence>-3/+2</bridge_temp_confidence> 
    <bridge_frost>NO</bridge_frost> 
    </hour> 
+ <hour id="06/02/2009 19:00CDT"> 
    <air_temp>61</air_temp> 
    <cloud_cover>mostly cloudy</cloud_cover> 
    <dew_point>52</dew_point> 
    <precip_prob>10</precip_prob> 
    <precip_rate>trace</precip_rate> 
    <precip_type>rain</precip_type> 
    <snow_rate>0.0</snow_rate> 
    <wind_direction>ENE</wind_direction> 
    <wind_speed>7</wind_speed> 
    <dew_point_confidence>-3/+4</dew_point_confidence> 
    <road_temp>68</road_temp> 
    <road_frost_prob>0</road_frost_prob> 
    <road_potential_evap_rate>959</road_potential_evap_rate> 
    <road_temp_confidence>-3/+3</road_temp_confidence> 
    <dew_point_confidence>-3/+4</dew_point_confidence> 
    <bridge_temp>66</bridge_temp> 
    <bridge_temp_confidence>-3/+3</bridge_temp_confidence> 
    <bridge_frost>NO</bridge_frost> 
    </hour> 
+ <hour id="06/02/2009 20:00CDT"> 
    <air_temp>60</air_temp> 
    <cloud_cover>mostly cloudy</cloud_cover> 
    <dew_point>51</dew_point> 
    <precip_prob>10</precip_prob> 
    <precip_rate>trace</precip_rate> 
    <precip_type>rain</precip_type> 
    <snow_rate>0.0</snow_rate> 
    <wind_direction>ENE</wind_direction> 
    <wind_speed>5</wind_speed> 
    <dew_point_confidence>-3/+4</dew_point_confidence> 
    <road_temp>65</road_temp> 
    <road_frost_prob>0</road_frost_prob> 
    <road_potential_evap_rate>495</road_potential_evap_rate> 
    <road_temp_confidence>-3/+4</road_temp_confidence> 
    <dew_point_confidence>-3/+4</dew_point_confidence> 
    <bridge_temp>62</bridge_temp> 
    <bridge_temp_confidence>-3/+3</bridge_temp_confidence> 
    <bridge_frost>NO</bridge_frost> 
    </hour> 
+ <hour id="06/02/2009 21:00CDT"> 
    <air_temp>57</air_temp> 
    <cloud_cover>mostly cloudy</cloud_cover> 
    <dew_point>51</dew_point> 
    <precip_prob>0</precip_prob> 
    <precip_rate>0.00</precip_rate> 
    <precip_type>none</precip_type> 
    <snow_rate>0.0</snow_rate> 
    <wind_direction>NE</wind_direction> 
    <wind_speed>5</wind_speed> 
    <dew_point_confidence>-3/+4</dew_point_confidence> 
    <road_temp>62</road_temp> 
    <road_frost_prob>0</road_frost_prob> 
    <road_potential_evap_rate>339</road_potential_evap_rate> 
    <road_temp_confidence>-3/+4</road_temp_confidence> 
    <dew_point_confidence>-3/+4</dew_point_confidence> 
    <bridge_temp>59</bridge_temp> 
    <bridge_temp_confidence>-3/+3</bridge_temp_confidence> 
    <bridge_frost>NO</bridge_frost> 
    </hour> 
+ <hour id="06/02/2009 22:00CDT"> 
    <air_temp>56</air_temp> 
    <cloud_cover>mostly cloudy</cloud_cover> 
    <dew_point>51</dew_point> 
    <precip_prob>0</precip_prob> 
    <precip_rate>0.00</precip_rate> 
    <precip_type>none</precip_type> 
    <snow_rate>0.0</snow_rate> 
    <wind_direction>ENE</wind_direction> 
    <wind_speed>5</wind_speed> 
    <dew_point_confidence>-3/+4</dew_point_confidence> 
    <road_temp>60</road_temp> 
    <road_frost_prob>0</road_frost_prob> 
    <road_potential_evap_rate>309</road_potential_evap_rate> 
    <road_temp_confidence>-3/+4</road_temp_confidence> 
    <dew_point_confidence>-3/+4</dew_point_confidence> 
    <bridge_temp>58</bridge_temp> 
    <bridge_temp_confidence>-3/+3</bridge_temp_confidence> 
    <bridge_frost>NO</bridge_frost> 
    </hour>

Source

2009-08-26 user3273269

Pourquoi est-ce wiki communautaire? Les gens ne vont pas vouloir vous aider avec votre problème s'ils ne peuvent pas obtenir de représentant pour cela. –

Si vous voulez max temp, pourquoi demander wind_gust? – Cheeso

choses Couple:

Je ne vois pas d'éléments pour County = "Adams". Le document que vous avez donné avait comté = "Adair". Je pense que vous essayez de faire un CInt() sur une chaîne qui ressemble à <wind_gust>15</wind_gust>. Il n'y a pas d'élément <wind_gust> pour le comté Adair et 12: 00CDT. J'ai donc demandé 15: 00CDT, ce qui m'a donné un élément wind_gust. Si vous interrogez sur une heure qui n'a pas d'élément wind_gust, vous obtiendrez l'ensemble vide.
Vous avez dit que vous vouliez une température maximale, mais vous êtes en train d'interroger wind_gust. Je ne vois aucun élément appelé max_temp.

Ce code fonctionne pour moi:

Public Sub QueryWindGust(ByVal county As String, ByVal hour As String) 
    Dim document = XDocument.Load("meridian.xml") 
    Dim selection = From c In document.Root.Elements("county") _ 
     Where c.Attribute("name").Value = "Adair" _ 
     From h In c.Elements("hour") _ 
     Where h.Attribute("id").Value = hour _ 
     From g In h.Elements("wind_gust") _ 
     Select CInt(g.Value) 


    Console.WriteLine("For county {0}, hour ({1}):", county, hour) 
    If (selection.Count > 0) 
     Console.Write("wind gust: ") 
     For Each m In selection 
      Console.WriteLine(m.ToString() & ": (" & m.GetType().ToString() & ")") 
     Next 
    Else 
     Console.WriteLine("No elements returned.") 
    End If 
End Sub 

Public Sub Run() 
    QueryWindGust("Adams","06/02/2009 12:00CDT") 
    QueryWindGust("Adair","06/02/2009 12:00CDT") 
    QueryWindGust("Adair","06/02/2009 15:00CDT") 
End Sub

Source

2009-08-26 21:49:10 Cheeso

Comment utiliser la clause Where pour correspondre à la condition DateTime

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