WRONGTYPE Operation against a key holding the wrong kind of value php

Question

Redis supports 6 data types. You need to know what type of value that a key maps to, as for each data type, the command to retrieve it is different.

Here are the commands to retrieve key value:

• if value is of type string -> GET <key>
• if value is of type hash -> HGETALL <key>
• if value is of type lists -> lrange <key> <start> <end>
• if value is of type sets -> smembers <key>
• if value is of type sorted sets -> ZRANGEBYSCORE <key> <min> <max>
• if value is of type stream -> xread count <count> streams <key> <ID>. https://redis.io/commands/xread

Use the TYPE command to check the type of value a key is mapping to:

• type <key>

This error means that the value indexed by the key "l_messages" is not of type hash, but rather something else. You've probably set it to that other value earlier in your code. Try various other value-getter commands, starting with GET, to see which one works and you'll know what type is actually here.

This error says that you are trying to push a wrong value into the key, which means that there already exists same key but with different data structure.

To get all the keys do this in the redis cli

keys *

This should display all the keys Now to get the type of value the key stores, do

type <key>

so it says what value you can push into the key. In my case the type was string (using set) and i was trying to use the key as list

I faced this issue when trying to set something to redis. The problem was that I previously used "set" method to set data with a certain key, like

$redis->set('persons', $persons)

Later I decided to change to "hSet" method, and I tried it this way

foreach($persons as $person){
    $redis->hSet('persons', $person->id, $person);
}

Then I got the aforementioned error. So, what I had to do is to go to redis-cli and manually delete "persons" entry with

del persons

It simply couldn't write different data structure under existing key, so I had to delete the entry and hSet then.