Question

我正在尝试从JSON.Net中使用magicthegathering.io方法从SelectTokens获得的一些JSON中获取一些信息。但是，当我尝试这样做时，我收到错误“无法读取查询运算符”。

这是我正在使用的代码：

JToken jtoken = JToken.Parse(
    @"{""cards"":[{""name"":""Krark-Clan Engineers"",""manaCost"":""{3}{R}"",""cmc"":4,""colors"":[""Red""],""type"":""Creature — Goblin Artificer"",""types"":[""Creature""],""subtypes"":[""Goblin"",""Artificer""],""rarity"":""Uncommon"",""set"":""5DN"",""text"":""{R}, Sacrifice two artifacts: Destroy target artifact."",""flavor"":""\""Well, I jammed the whatsit into the whackdoodle, but I think I broke the thingamajigger.\"""",""artist"":""Pete Venters"",""number"":""70"",""power"":""2"",""toughness"":""2"",""layout"":""normal"",""multiverseid"":50201,""imageUrl"":""http://gatherer.wizards.com/Handlers/Image.ashx?multiverseid=50201&type=card"",""foreignNames"":[{""name"":""喀勒克族机械工"",""language"":""Chinese Simplified"",""multiverseid"":81620},{""name"":""Ingénieurs du clan Krark"",""language"":""French"",""multiverseid"":80795},{""name"":""Ingenieure des Krark-Clans"",""language"":""German"",""multiverseid"":80960},{""name"":""Ingegneri di Krark-Clan"",""language"":""Italian"",""multiverseid"":81290},{""name"":""クラーク族の技師"",""language"":""Japanese"",""multiverseid"":80630},{""name"":""Engenheiros do Clã-de-Krark"",""language"":""Portuguese (Brazil)"",""multiverseid"":81455},{""name"":""Ingenieros del clan Krark"",""language"":""Spanish"",""multiverseid"":81125}],""printings"":[""5DN""],""originalText"":""{R}, Sacrifice two artifacts: Destroy target artifact."",""originalType"":""Creature — Goblin Artificer"",""legalities"":[{""format"":""Commander"",""legality"":""Legal""},{""format"":""Freeform"",""legality"":""Legal""},{""format"":""Legacy"",""legality"":""Legal""},{""format"":""Mirrodin Block"",""legality"":""Legal""},{""format"":""Modern"",""legality"":""Legal""},{""format"":""Prismatic"",""legality"":""Legal""},{""format"":""Singleton 100"",""legality"":""Legal""},{""format"":""Tribal Wars Legacy"",""legality"":""Legal""},{""format"":""Vintage"",""legality"":""Legal""}],""id"":""a4d05fd27ec5d7df470e91218f1ca885eda4f0c6""}]}"
);

var foundTokens = jtoken.SelectTokens(@"$..cards[?(@.name=""Krark - Clan Engineers"")].imageUrl", true);
if (foundTokens.Any())
{
    string selected = foundTokens.Last().ToString();
    Console.WriteLine("Found: " + selected);
}
else
{
    Console.WriteLine("Found nothing!");
}

（Here是一个如上所示相同代码的小提琴。）

当我尝试使用在线JSONPath测试工具（例如here或here）获得相同的路径时，它按预期工作。

为什么这不适用于JSON.Net？我该如何解决？

谢谢！

Answer 1

您必须使用==进行字符串比较; =仅用于数值。
您必须将字符串括在单引号中。

e.g。 @.name=='Krark - Clan Engineers')

forked fiddle

SelectTokens中的JSON.Net“无法读取查询运算符”

1 个答案: