ruby hash map collect

ruby map



Ruby utilizando el método abreviado "&: methodname" de array.map(&: methodname) para cadenas de clave hash en lugar de namename (2)

La mayoría de los desarrolladores de ruby ​​saben cómo guardar unas pocas pulsaciones haciendo algo como esto:

array.map(&:methodname)

más bien que

array.map {|x| x.methodname }

¿Hay alguna manera de aplicar un método abreviado similar de &: methodname para llamar a "métodos" (valores llamados mediante claves) en una matriz de hashes?

En mi caso, los resultados con JSON api se devuelven en lotes de 60 como matrices de hashes originados en JSON. Intenté hacer esto pero no tuve éxito:

array.map(&:"keyname")

pero no fue exitoso, lanzando un NoMethodError y diciendo que no hay un método de ''nombre de clave'' para Hash, lo cual es razonable, creo. Me pregunto si hay alguna bala mágica para emular este &:... atajo de hashes que los chicos ruby ​​ya han resuelto.

Aquí está una de las respuestas JSON reales, limitada a 5 resultados, creo

[{"geometry":{"location":{"lat":33.723008,"lng":-78.930593}},"icon":"http://maps.gstatic.com/mapfiles/place_api/icons/bowling-71.png","id":"095e108208879fe989f2b36e81e38bafe0c17574","name":"Waccamaw Bowling Center","opening_hours":{"open_now":true},"photos":[{"height":612,"html_attributions":["/u003Ca href=/"https://plus.google.com/106701205257534874835/"/u003EAndy Badi/u003C/a/u003E"],"photo_reference":"CoQBeQAAANZ3d4xBep-4jlCnHp0IcCfSr4k6WVnAMDkPNPhlhSTaZ-NICdLaPVxaRW04qK8ko8x5SDScTeImNKWo2qlyF0JYTQpy-elxdZkx58BYQsjCLdtOaBr_yIoKk3NSuBGk7RS9Lf2IWpW0NaBjeAcPTNdKKHoTt_PZ4212cD67wV0jEhBmRx62d9nUyBmPkrv51nadGhTXEhV-hA5frdzGKal4tEd2pYPtjQ","width":816}],"rating":3.1,"reference":"CoQBeAAAAD5d1gIGf4AG427DlKp-AC74Wt5ZCTd6uPU0-31qTnDRW3mBk4Scq00zjaLpbXnqvs1rlMgEFHPVId9nPGU5oaWr2nYRqRodz5LGdVpZqHx1R_PRciZX7xb068t6c7bqw7Fy_Bs9YIi8pCNdfAdHEZb8Pjxy1mpnL1qN_DBz243eEhCrzUmU34savXzZijjlv8TzGhSX3SofvWtuGYOhhPol9atp3aTSyQ","types":["bowling_alley","establishment"],"vicinity":"101 Philip Gray Drive, Myrtle Beach"},{"geometry":{"location":{"lat":33.817622,"lng":-78.692496}},"icon":"http://maps.gstatic.com/mapfiles/place_api/icons/bowling-71.png","id":"12fed6fbc66c7d9fc693fe37e6834e32ee6e23b9","name":"North Myrtle Beach Bowling Center","photos":[{"height":460,"html_attributions":["/u003Ca href=/"https://plus.google.com/100443525307746960711/"/u003EHolly Heniford/u003C/a/u003E"],"photo_reference":"CpQBhwAAADY5u5bWSEVGRZr1A7LR0Dpli5EEDRvOt5oWvzQYCOvRk1XO9bMBPdKvQYy_TwSHDcRRcqo6JZoGyLc-nLvlOoG1gX133KkdJ7lKU33RC9hdeN_dzfAUoxIrArZK8Ssu2QQWpXmq10xsJKPIu2bAzpS3n3vKqLdeKZY86GPw7LR0cM-Su3P0MZiY2AkC7uIJIhIQkQVG3s7We7yNPlqRqBkE4xoULTYXh2O6PPuki5_TXG3tN1O3kLg","width":816}],"reference":"CpQBgwAAAB0eZVssHlDn56UET5IqUpZygTzWdLclQ73lU0xzgNG875YyQPhQWGvOI2ciZq_BO6yZYzjMIdGEFVI-jnOhj_Y56Eq0T1MaLAL0dIkCM9qS4QwjAv3-TjwJOMBnN7aARHr3BuGqYLQZb5fkN3veUr2tWLKDZcPT1SHXRLypDutO5msurlQLub5YgmNhOomPdxIQLbIFLMxiqssFIUbO6bEcrRoU0A49j-VRMk4vHsSqxADOq5OPo1o","types":["bowling_alley","establishment"],"vicinity":"1105 Highway 17S, North Myrtle Bch"},{"geometry":{"location":{"lat":33.617718,"lng":-78.976797}},"icon":"http://maps.gstatic.com/mapfiles/place_api/icons/bowling-71.png","id":"5b2bcc16481ea7519f5e2858d4aa8af1b836f3c8","name":"Surfside Bowling Center","rating":4.4,"reference":"CoQBeQAAACW_aubzCjtG19Nw9Pm9RIXpzpgXD5rFyKziCYy0Uc7X9g1vVz2YWoDUmXwIYA9uUksSArTypwe8lh76TjYYTnNIPiTXc_dpgw94XGaQwC1dO5DuMBPLtWyKgY4Jqa8UlYdHnTOe4FPJnZV7gTsx25Eid2iasa07gruGui6tltYtEhBpBraa9i7GzEE3FUYWxUU0GhSsfU66SAn8tpT3Oa_PRkTUYLXlCQ","types":["bowling_alley","establishment"],"vicinity":"510 U.S. 17 Business, Surfside Beach"},{"geometry":{"location":{"lat":33.580683,"lng":-79.024837}},"icon":"http://maps.gstatic.com/mapfiles/place_api/icons/bowling-71.png","id":"259104d58ff8e1aebe70db6149c74c736500a069","name":"Frank Theatres","opening_hours":{"open_now":true},"photos":[{"height":400,"html_attributions":[],"photo_reference":"CnRnAAAAq26m02SGow16WCPVIvqioB646tx-kq39g-KPZ6rydR4gUFS2eFF_M3f0-ntrLiq-Iv3jjiQfUdVt_qMxYSAxxOxhfW9JucBG9-Z4ddJH-teNg6p62rHu5Ebbxs-CI40xoK78w3rdLbYA6GsWaOL5gRIQ5UBFXus-gXSy1UrWQ_aiixoUFE0H2eqxYpFyzbGkQtbq4nUHgUk","width":300}],"reference":"CnRvAAAAMDm7HoTk9pG-nKJGvzl9QIw6Qhso44Nh5Q0-xOwM5rykjQ12DJiF_2vZRMaUk9bOtNJwW9ntoBpTgj6bHtWiVCP3OlMu-gd0dgMygMvrIxGTkaR3cTKab0KuHHnoCFxdVB7esI-rK0v585lWS6xTZxIQ0gFfzO3vhZGkIjF6ThDgNBoUAYAMJyjC7f__SBcqOLKbDl3pFSQ","types":["bowling_alley","restaurant","food","movie_theater","establishment"],"vicinity":"10125 Frontage Road #12f, Murrells Inlet"},{"geometry":{"location":{"lat":33.959856,"lng":-78.400399}},"icon":"http://maps.gstatic.com/mapfiles/place_api/icons/bowling-71.png","id":"39a632e654125e6aa73a526579cae55cc14ee4a2","name":"Brunswick County Bowling Center","reference":"CoQBgAAAAETfTwuwFT34ynta7FJFME2kBVM0XurlJJKj3IQMaOXlWqTGU2P2L4l3gX9XP3XkGSgbxsQiOxIpGiTkrKRVV_-EzvGMNeE8IpsmSUMY7SBY-w7SlC6DGtlX1Py-YES6ZSTrM36my9f6Y2s7bAqamlvXbdtGfTgJpycuI0cx28fvEhB7Y-gtYgRCIInlgHxli4ygGhQlgaJt7d4PylH0KJBnzjRJeIKbNA","types":["bowling_alley","establishment"],"vicinity":"630 Village Rd SW, South Brunswick"},{"geometry":{"location":{"lat":33.974945,"lng":-78.396355}},"icon":"http://maps.gstatic.com/mapfiles/place_api/icons/generic_business-71.png","id":"abaf128a51021a535a17b1af4a523a5fc3af7d10","name":"Planet Fun","photos":[{"height":485,"html_attributions":[],"photo_reference":"CnRtAAAACFYcotbimoFO1Jrqiy7PgLZ3Uuq4t1BLKvrewRdsV0aUZ4ay1jwtCaDQ-q2sh7EweO5At2YA3Mg-tukES9UXItwOn2uLD2sXenKg2UhkBSwa-bvd4RGAH-dg0uACDU_0_kCi7xHkv5WrgSiKmBVN8hIQYBr23I1W9dOQ5F6Rdn1wfRoUVBdp3FEoKA_0e29nzlnUem15BJs","width":1024}],"rating":2.8,"reference":"CnRrAAAARZu90zQ_rp_pRX80BxqorM2GecSJ9kUkRnWNWEDx5K5JXwe9qgPdkzMsq8yOxITR1iPmS6knSWKNO-eWhYxBtJSti7O0ar1kkK2lBUhS5Kn6AxuT8bxlyuKLSuiGN3Zi-YFXI6d4nxhL7uO3K8LAnxIQNJ5TMpFhegaM3saANGrubBoUD7D9lw61ng3SmpK4g1dzf1cIVJ4","types":["amusement_park","establishment"],"vicinity":"349 Whiteville Road Northwest, Shallotte"}]

Puedes hacer esto con un lambda:

extract_keyname = ->(h) { h[:keyname] } ary_of_hashes.map(&extract_keyname)

Esto tiende a ser más útil si la lógica del bloque es más complicada que simplemente extraer un valor de un Hash. Además, adjuntar nombres a sus bits de lógica puede ayudar a aclarar lo que está tratando de hacer una cadena de llamadas a métodos Enumerables.

También puedes tener un lambda que devuelve un lambda si lo haces varias veces:

extract = ->(k) { ->(h) { h[k] } } ary_of_hashes.map(&extract[:keyname]) ary_of_hashes.map(&extract[:other_key])

o un método de construcción lambda:

def extract(k) ->(h) { h[k] } end ary_of_hashes.map(&extract(:keyname)) ary_of_hashes.map(&extract(:other_key))