在elixir中将EXTO模式写入csv文件？

嗨，我在长生不老药里有这样的人

[
  %Texting.Contact.Person{
    __meta__: #Ecto.Schema.Metadata<:loaded, "people">,
    email: nil,
    name: "John",
    phone_number: "13334445555",
    phonebook: #Ecto.Association.NotLoaded<association :phonebook is not loaded>,
    phonebook_id: 60,
    previous_phonebook_id: 60,
    subscribed: true,
    updated_at: ~N[2018-09-22 14:36:04.788163],
    user: #Ecto.Association.NotLoaded<association :user is not loaded>,
    user_id: 54
  },
  %Texting.Contact.Person{
    __meta__: #Ecto.Schema.Metadata<:loaded, "people">,
    email: nil,
    name: "Rhee",
    phone_number: "14443335555",
    phonebook: #Ecto.Association.NotLoaded<association :phonebook is not loaded>,
    phonebook_id: 60,
    previous_phonebook_id: 60,
    subscribed: true,
    updated_at: ~N[2018-09-22 14:36:13.671479],
    user: #Ecto.Association.NotLoaded<association :user is not loaded>,
    user_id: 54
  }
]

** (Protocol.UndefinedError) protocol String.Chars not implemented for #Function<62.51129937/2 in Stream.transform/3>. This protocol is implemented for: Atom, BitString, Date, DateTime, Decimal, Ecto.Date, Ecto.DateTime, Ecto.Time, Float, Floki.Selector, Floki.Selector.AttributeSelector, Floki.Selector.Combinator, Floki.Selector.Functional, Floki.Selector.PseudoClass, Integer, List, NaiveDateTime, Postgrex.Copy, Postgrex.Query, Postgrex.Stream, Time, URI, Version, Version.Requirement
    (elixir) /home/ubuntu/bob/tmp/0a92cc555e2418d1b56e3b10e5321a85/elixir/lib/elixir/lib/string/chars.ex:3: String.Chars.impl_for!/1
    (elixir) /home/ubuntu/bob/tmp/0a92cc555e2418d1b56e3b10e5321a85/elixir/lib/elixir/lib/string/chars.ex:22: String.Chars.to_string/1
    (elixir) lib/io.ex:553: IO.write/2
    (elixir) lib/enum.ex:1314: Enum."-map/2-lists^map/1-0-"/2

但我犯了这样的错误

[
  %Texting.Contact.Person{
    __meta__: #Ecto.Schema.Metadata<:loaded, "people">,
    email: nil,
    name: "John",
    phone_number: "13334445555",
    phonebook: #Ecto.Association.NotLoaded<association :phonebook is not loaded>,
    phonebook_id: 60,
    previous_phonebook_id: 60,
    subscribed: true,
    updated_at: ~N[2018-09-22 14:36:04.788163],
    user: #Ecto.Association.NotLoaded<association :user is not loaded>,
    user_id: 54
  },
  %Texting.Contact.Person{
    __meta__: #Ecto.Schema.Metadata<:loaded, "people">,
    email: nil,
    name: "Rhee",
    phone_number: "14443335555",
    phonebook: #Ecto.Association.NotLoaded<association :phonebook is not loaded>,
    phonebook_id: 60,
    previous_phonebook_id: 60,
    subscribed: true,
    updated_at: ~N[2018-09-22 14:36:13.671479],
    user: #Ecto.Association.NotLoaded<association :user is not loaded>,
    user_id: 54
  }
]

** (Protocol.UndefinedError) protocol String.Chars not implemented for #Function<62.51129937/2 in Stream.transform/3>. This protocol is implemented for: Atom, BitString, Date, DateTime, Decimal, Ecto.Date, Ecto.DateTime, Ecto.Time, Float, Floki.Selector, Floki.Selector.AttributeSelector, Floki.Selector.Combinator, Floki.Selector.Functional, Floki.Selector.PseudoClass, Integer, List, NaiveDateTime, Postgrex.Copy, Postgrex.Query, Postgrex.Stream, Time, URI, Version, Version.Requirement
    (elixir) /home/ubuntu/bob/tmp/0a92cc555e2418d1b56e3b10e5321a85/elixir/lib/elixir/lib/string/chars.ex:3: String.Chars.impl_for!/1
    (elixir) /home/ubuntu/bob/tmp/0a92cc555e2418d1b56e3b10e5321a85/elixir/lib/elixir/lib/string/chars.ex:22: String.Chars.to_string/1
    (elixir) lib/io.ex:553: IO.write/2
    (elixir) lib/enum.ex:1314: Enum."-map/2-lists^map/1-0-"/2

**（Protocol.UndefinedError）协议字符串。未为#函数实现字符。该协议的实现对象为：Atom、BitString、Date、DateTime、Decimal、Ecto.DateTime、Ecto.Time、Float、Floki.Selector、Floki.Selector.AttributeSelector、Floki.Selector.Combinator、Floki.Selector.Functional、Floki.Selector.PseudoClass、Integer、List、NaiveDateTime、Postgrex.Copy、Postgrex.Query、Postgrex.Stream、Time、URI、Version、，版本.要求
（elixir）/home/ubuntu/bob/tmp/0a92cc555e2418d1b56e3b10e5321a85/elixir/lib/elixir/lib/string/chars.ex:3:string.chars.impl_for/1.
（elixir）/home/ubuntu/bob/tmp/0a92cc555e2418d1b56e3b10e5321a85/elixir/lib/elixir/lib/string/chars.ex:22:string.chars.to_string/1
（elixir）lib/io.ex:553:io.write/2
（elixir）lib/enum.ex:1314:enum。“-map/2-lists^map/1-0-”/2

我想做的是只保存姓名和电话号码字段到csv文件格式。 如何执行此操作？

根据，

CSV.encode/2

获取字符串列表，但没有您尝试使用的选项

我是这样做的：

def write!(people) do
  people
  |> Stream.map(&[&1.name, &1.phone_number])
  |> CSV.encode()
  |> Enum.into(File.stream!("contacts.csv"))
end

Enum.map

创建一个字符串列表，然后对其进行编码并流式传输到

contacts.csv

要在顶部添加标题行，可以使用

Stream.concat/2

预先添加标题行：

def write!(people) do
  [["name", "phone_number"]]
  |> Stream.concat(people |> Stream.map(&[&1.name, &1.phone_number]))
  |> CSV.encode()
  |> Enum.into(File.stream!("contacts.csv"))
end

根据，

CSV.encode/2

获取字符串列表，并且没有您尝试使用的选项

我是这样做的：

def write!(people) do
  people
  |> Stream.map(&[&1.name, &1.phone_number])
  |> CSV.encode()
  |> Enum.into(File.stream!("contacts.csv"))
end

Enum.map

创建一个字符串列表，然后对其进行编码并流式传输到

contacts.csv

要在顶部添加标题行，可以使用

Stream.concat/2

预先添加标题行：

def write!(people) do
  [["name", "phone_number"]]
  |> Stream.concat(people |> Stream.map(&[&1.name, &1.phone_number]))
  |> CSV.encode()
  |> Enum.into(File.stream!("contacts.csv"))
end

---

你在用还是别的什么？你在用还是别的什么？谢谢你的回复。但我犯了个错误

code

**（FunctionClauseError）文件中没有匹配的函数子句。normalize_modes/2为File.normalize_modes/2提供了以下参数：#1“contacts.csv”#2个真正尝试的函数子句（显示6个函数子句中的6个）：defp normalize_modes（[：utf8 | rest]，binary？）defp normalize_modes（[：read|ahead | rest]，binary？）defp normalize_modes（[mode | rest]，_binary？）mode==：char|list或mode==：charlist defp normalize_modes（[mode | rest]，binary？）defp normalize| modes（[]，true）抱歉

File.stream行完全错误。你能试试编辑过的代码吗？我不需要使用IO.write函数来写入文件吗？不，
file.stream
打开一个流，然后
Enum.into
写入其中。无需手动调用
IO。编写
。感谢您的回复。但我犯了个错误
code
**（FunctionClauseError）文件中没有匹配的函数子句。normalize_modes/2为File.normalize_modes/2提供了以下参数：#1“contacts.csv”#2个真正尝试的函数子句（显示6个函数子句中的6个）：defp normalize_modes（[：utf8 | rest]，binary？）defp normalize_modes（[：read|ahead | rest]，binary？）defp normalize_modes（[mode | rest]，_binary？）mode==：char|list或mode==：charlist defp normalize_modes（[mode | rest]，binary？）defp normalize| modes（[]，true）抱歉
File.stream行完全错误。你能试试编辑过的代码吗？我不需要使用IO.write函数来写入文件吗？不，
file.stream
打开一个流，然后
Enum.into
写入其中。无需手动调用
IO.write
。