如何检查哈希中的键是否存在（redis）？

Question

How do I check if a key inside a hash exists (redis)?

I tried this way:

redisClient.exists(obj.mydict.user.toString().pos, function(err,reply) {
                if(!err) {
                    if(reply !== null) {
                    ...

however I get:

node_redis: Deprecated: The EXISTS command contains a "undefined" argument.
This is converted to a "undefined" string now and will return an error from v.3.0 on.
Please handle this in your code to make sure everything works as you intended it to.

I do not know how. What I'm trying is to check if my .pos key exists in my hash obj.mydict.user.toString() , how would it do it in node_redis ?

Answer 1

虽然没有特定的命令来检查Redis哈希中字段是否存在，但是您可以调用HGET并从nil答复中推断出不存在。

Answer 2

How about using in?

var hash = {'a': 1, 'b': 2};
console.log('a' in hash);
console.log('c' in hash);

Answer 3

   // you can use 'hget' to check the existence of your key in particular hash like as follow:

client.hget('HASH NAME', 'mykey',function(err, result) 
        {
             if(err)
              console.log(err.message);
             console.log(JSON.stringify(result)); 

        });