key

问题 Im wondering how i could show the dictionary key itself in a django template Example dictionary: resources = {'coin': coin, 'grain': grain, 'iron': iron, 'stone': stone, 'wood': wood,} Template <b>Coin: </b>{{ upgrade.coin }} Were i want to use the dictionary key (+some html) instead of the hard coded "Coin:" Can anyone please help me out? 回答1: Use for tag with dict.items if you want to print all key/value pairs: {% for key, value in resources.items %} <b>{{ key }}: </b>{{ value }} {% endfor

问题 I'm using ON DUPLICATE KEY UPDATE to handle duplicate inserts on a table, in order that they are discarded. In my case it's a simple table storing tags: id (int, PK, AI, unsigned, not null) tag (varchar 25, not null, unique) This is working fine, but I need to retrieve the ID - either the insert ID, on successful insert, or the existing ID, if it's a duplicate. I'm getting insert ID = 0 where ON DUPLICATE KEY UPDATE fires, which I guess is expected behaviour since no insert took place. Is

问题 I'm using ON DUPLICATE KEY UPDATE to handle duplicate inserts on a table, in order that they are discarded. In my case it's a simple table storing tags: id (int, PK, AI, unsigned, not null) tag (varchar 25, not null, unique) This is working fine, but I need to retrieve the ID - either the insert ID, on successful insert, or the existing ID, if it's a duplicate. I'm getting insert ID = 0 where ON DUPLICATE KEY UPDATE fires, which I guess is expected behaviour since no insert took place. Is

问题 I have two jsons. First: here Second: here How to sort second json by first? I want to sort keys and it's values in second json by values in first json. 回答1: You could do something like this var first = ["name0", "name1", "name2"] var second = { {"name2":"xyz", "name0" : "xyz", "name1" : "xyz" } } for( var i = 1; i < Object.keys(second).length; i++ ){ var aux = {} first.forEach(function(element2) { resul[element2] = second[i][element2] }); } 来源： https://stackoverflow.com/questions/54029071

问题 I'm quite new to react and I'm facing a problem I can't solve. Here is my react component: import React from 'react'; import Header from './Header'; import ContestPreview from './ContestPreview'; class App extends React.Component { state = { pageHeader: 'Naming Contests', whatever: 'test' }; render() { return ( <div className="App"> <Header message={this.state.pageHeader} /> <div> {this.props.contests.map(contest => <ContestPreview key={contest.id} {...contest} /> )} </div> </div> ); } }

问题 Say I have a dictionary with one key (and a value): dict = {'key': '500'}. Now I want to add a new value '1000' to the same key. However, dict[key].append('1000') just gives me "AttributeError: 'str' object has no attribute 'append'". If I do dict[key] = '1000' it replaces the previous value. I'm guessing I have to create a list as a value and somehow append that list as the key's value but I'm not sure how I would go about this. Thanks for any help! 回答1: I suggest the usage of a defaultdict

问题 I have saved lists in following format in my Redis database. key:inner-key1:inner-key2:inner-key3 For example my database looks like this: A:B:X:val1 A:B:Y:val2 A:C:X:val3 A:C:Y:val4 How can I get inner keys for key B? I was trying to get it using KEYS A:B:*, but result of this are whole lines "A:B:X:val1" and "A:B:X:val2". All I need is to get only first inner key of "A:B" in format for example [X, Y]. 回答1: You can use Redis Hash to acheive the same: Your Keys are A:B:X:val1 A:B:Y:val2 A:C:X

问题 I have saved lists in following format in my Redis database. key:inner-key1:inner-key2:inner-key3 For example my database looks like this: A:B:X:val1 A:B:Y:val2 A:C:X:val3 A:C:Y:val4 How can I get inner keys for key B? I was trying to get it using KEYS A:B:*, but result of this are whole lines "A:B:X:val1" and "A:B:X:val2". All I need is to get only first inner key of "A:B" in format for example [X, Y]. 回答1: You can use Redis Hash to acheive the same: Your Keys are A:B:X:val1 A:B:Y:val2 A:C:X

问题 Say I have a dictionary built like this: d={0:1, 1:2, 2:3, 10:4, 11:5, 12:6, 100:7, 101:8, 102:9, 200:10, 201:11, 202:12} and I want to create a subdictionary d1 by slicing d in such a way that d1 contains the following keys: 0, 1, 2, 100, 101, 102 . The final output should be: d1={0:1, 1:2, 2:3, 100:7, 101:8, 102:9} Is there an efficient Pythonic way of doing this, given that my real dictionary contains over 2,000,000 items? I think this question applies to all cases where keys are integers,

问题 Is it right to expect that, for the typical modern RDBMS, querying by one specific primary key is as fast as querying a hashtable by key? Or is there "actual work" done to traverse the table and track down the primary key value? That seems unthinkably wasteful, even if there are automatic indexes for primary keys. 回答1: Database operation involves access of secondary memory unit (Disk). And to achieve efficiency important is to reduce block access time(not operations). Complexity of Select