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copied!<p>There are multiple ways to debug a Redis client with node.js.</p> <p>First you can rely on the Redis monitor feature to log every commands received by the Redis server:</p> <pre><code>> src/redis-cli monitor OK 1371134499.182304 [0 172.16.222.72:51510] "info" 1371134499.185190 [0 172.16.222.72:51510] "zinterstore" "tmp" "2" "red,round" </code></pre> <p>You can see the zinterstore command received by Redis is ill-formed.</p> <p>Then, you can activate the debugging mode of node_redis by adding the following line in your script:</p> <pre><code>redis.debug_mode = true; </code></pre> <p>It will output the Redis protocol at runtime:</p> <pre><code>Sending offline command: zinterstore send ncegcolnx243:6379 id 1: *4 $11 zinterstore $3 tmp $1 2 $9 red,round send_command buffered_writes: 0 should_buffer: false net read ncegcolnx243:6379 id 1: -ERR syntax error </code></pre> <p>Then, you can use <a href="http://nodejs.org/api/debugger.html">node.js debugger</a>. Put a debugger breakpoint in the code in the following way:</p> <pre><code>function search(tags, page, callback) { debugger; // breakpoint is here client.ZINTERSTORE("tmp", tags.length, tags, function(err, replies){ console.log(err); console.log(replies); callback('ok') }); } </code></pre> <p>You can then launch the script with node in debug mode:</p> <pre><code>$ node debug test.js < debugger listening on port 5858 connecting... ok break in D:\Data\NodeTest\test.js:1 1 var redis = require("redis"); 2 var client = redis.createClient( 6379, "ncegcolnx243" ); 3 debug> help Commands: run (r), cont (c), next (n), step (s), out (o), backtrace (bt), setBreakpoint (sb), clearBreakpoint (cb), watch, unwatch, watchers, repl, restart, kill, list, scripts, breakOnException, breakpoints, version debug> cont break in D:\Data\NodeTest\test.js:8 6 function search(tags, page, callback) { 7 8 debugger; 9 client.ZINTERSTORE("tmp", tags.length, tags, function(err, replies){ 10 console.log(err); ... use n(ext) and s(tep) commands ... </code></pre> <p>By stepping through the code, you will realize that the command array is not correct because the tags are serialized and processed as a unique parameter.</p> <p>Changing the code as follows will fix the problem:</p> <pre><code>var cmd = [ "tmp", tags.length ]; client.zinterstore( cmd.concat(tags), function(err, replies) { ... }); </code></pre>

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