mybatis 里面的 collection 嵌套两层后，如果里面那层有两条数据，最后返回的是两个 json 字符串，目标是想得到 1 个 json 字符串。把类型改为 List 也不行，有没有大佬教一教我呀。

问题遇到的现象和发生背景

mybatis 里面的 collection 嵌套两层后，如果里面那层有两条数据，最后返回的是两个 json 字符串，目标是想得到 1 个 json 字符串。把类型改为 List 也不行，有没有大佬教一教我呀。

问题相关代码，

domain 层：

public class Alltest extends BaseEntity { private static final long serialVersiOnUID= 1L; private List<Treatmentinfo> treatmentinfoList; private List<Treatmentpciinfo> treatmentpciinfoList; private List<Outcomeinfo> outcomeinfoList; private List<Registerinfo> registerinfoList; private List<Firstaidinfo> firstaidinfoList; 其他的几个嵌套就是在另外的 class 里面再嵌套一个 List ，代码太长就不展示了 

因为全部数据太长了，我删除了中间的一些字段，保留前后数据和 collection 。 <resultMap id="AlltestResult" type="com.ruoyi.alltest.domain.Alltest"> <collection property="registerinfoList" javaType="java.util.List" resultMap="RegisterinfoResult"/> <collection property="firstaidinfoList" javaType="java.util.List" resultMap="FirstaidinfoResult"/> <collection property="outcomeinfoList" javaType="java.util.List" resultMap="OutcomeinfoResult"/> <collection property="treatmentinfoList" javaType="java.util.List" resultMap="TreatmentinfoResult"/> <collection property="treatmentpciinfoList" javaType="java.util.List" resultMap="TreatmentpciinfoResult"/> </resultMap> <!--人口信息表--> <resultMap type="com.ruoyi.patientme.domain.Registerinfo" id="RegisterinfoResult"> <result property="patientId" column="patient_id" /> <result property="register_id" column="REGISTER_ID" /> <result property="hospital_id" column="HOSPITAL_ID" /> <result property="name" column="NAME" /> <result property="gender" column="GENDER" /> <result property="age" column="AGE" /> <result property="birthday" column="BIRTHDAY" /> <result property="nation" column="NATION" /> <result property="fillin_person" column="FILLIN_PERSON" /> <result property="submit_audit_person" column="SUBMIT_AUDIT_PERSON" /> <result property="auditor" column="AUDITOR" /> <result property="archiving_person" column="ARCHIVING_PERSON" /> </resultMap> <!--急救信息表--> <resultMap type="com.ruoyi.emergencyaid.domain.Firstaidinfo" id="FirstaidinfoResult"> <result property="patientId" column="patient_id" /> <result property="inpatient_id" column="INPATIENT_ID" /> <result property="outpatient_id" column="OUTPATIENT_ID" /> <result property="attack_time" column="ATTACK_TIME" /> <result property="is_null_attack_detail_time" column="IS_NULL_ATTACK_DETAIL_TIME" /> <result property="attack_zone" column="ATTACK_ZONE" /> <result property="province" column="PROVINCE" /> <result property="city" column="CITY" /> <result property="area" column="AREA" /> <result property="attack_address" column="ATTACK_ADDRESS" /> <result property="medical_insurance_type" column="MEDICAL_INSURANCE_TYPE" /> <result property="medical_insurance_no" column="MEDICAL_INSURANCE_NO" /> <result property="serious_illness_insurance" column="SERIOUS_ILLNESS_INSURANCE" /> <result property="consciousness_type column="CONSCIOUSNESS_TYPE" /> <result property="respiration_rate" column="RESPIRATION_RATE" /> <result property="pulse_rate" column="PULSE_RATE" /> <result property="heart_rate" column="HEART_RATE" /> <result property="throm_end_time" column="THROM_END_TIME" /> <result property="throm_drug_type" column="THROM_DRUG_TYPE" /> <result property="throm_drug_code" column="THROM_DRUG_CODE" /> <result property="is_repatency" column="IS_REPATENCY" /> <result property="start_radiography_time" column="START_RADIOGRAPHY_TIME" /> <result property="is_repci" column="IS_REPCI" /> <result property="operation_time" column="OPERATION_TIME" /> <result property="hospital_position" column="HOSPITAL_POSITION" /> <result property="patient_remark" column="PATIENT_REMARK" /> </resultMap> <resultMap type="com.ruoyi.outcomeme.domain.Outcomeinfo" id="OutcomeinfoResult"> <result property="patientId" column="patient_id" /> <result property="cp_diagnosis_code" column="CP_DIAGNOSIS_CODE" /> <result property="diagnosis_time" column="DIAGNOSIS_TIME" /> <result property="is_heart_failure" column="IS_HEART_FAILURE" /> <result property="pcsk9_name" column="PCSK9_NAME" /> <result property="pcsk9_dose" column="PCSK9_DOSE" /> <collection property="outdrugdetailsList" javaType="java.util.List" resultMap="OutdrugdetailsResult" /> </resultMap> <resultMap type="Outdrugdetails" id="OutdrugdetailsResult"> <id property="myDrugId" column="my_drug_id" /> <result property="drug_id" column="DRUG_ID" /> <result property="patientId" column="patient_id" /> <result property="type" column="TYPE" /> <result property="name" column="sub_name" /> <result property="dose" column="DOSE" /> <result property="rete_count" column="RETE_COUNT" /> <result property="rete_time" column="RETE_TIME" /> <result property="other_drug_name" column="OTHER_DRUG_NAME" /> </resultMap> <!--胸痛诊疗--> <resultMap type="Treatmentinfo" id="TreatmentinfoResult"> <id property="patientId" column="patient_id" /> <result property="has_ecg_image" column="HAS_ECG_IMAGE" /> <result property="no_ecg_image_reason" column="NO_ECG_IMAGE_REASON" /> <result property="await_doctor_name" column="AWAIT_DOCTOR_NAME" /> <result property="await_treatment_type" column="AWAIT_TREATMENT_TYPE" /> <result property="await_patient_remark" column="AWAIT_PATIENT_REMARK" /> <collection property="ctntsList" javaType="java.util.List" resultMap="CtntsRrsult" /> <collection property="ecgsList" javaType="java.util.List" resultMap="EcgsResult" /> </resultMap> <resultMap id="CtntsRrsult" type="Ctnts"> <id property="ctntsId" column="CTNTS_ID" /> <result property="ctntsPatientId" column="ctnts_patient_id" /> <result property="type" column="TYPE" /> <result property="value" column="VALUE" /> <result property="unit" column="UNIT" /> <result property="status" column="STATUS" /> <result property="blood_time" column="BLOOD_TIME" /> <result property="report_time" column="REPORT_TIME" /> </resultMap> <resultMap id="EcgsResult" type="Ecgs"> <id property="ecgId" column="ECG_ID" /> <result property="patientId" column="patient_id" /> <result property="ecg_time" column="ECG_TIME" /> <result property="ecg_diagnose_time" column="ECG_DIAGNOSE_TIME" /> <result property="ecgimagefiles" column="ECGImageFiles" /> </resultMap> <!--导管室--> <resultMap type="com.ruoyi.cathlab.domain.Treatmentpciinfo" id="TreatmentpciinfoResult"> <result property="patientId" column="patient_id" /> <result property="activate_conduit_time" column="ACTIVATE_CONDUIT_TIME" /> <result property="patient_arrived_conduit_time" column="PATIENT_ARRIVED_CONDUIT_TIME" /> <result property="auxiliary_device" column="AUXILIARY_DEVICE" /> <result property="complication" column="COMPLICATION" /> <collection property="coronaryAngiographieList" javaType="java.util.List" resultMap="CoronaryAngiographieResult" /> </resultMap> <resultMap id="CoronaryAngiographieResult" type="CoronaryAngiographie"> <id property="caId" column="CA_ID" /> <result property="caPatientId" column="ca_patient_id" /> <result property="position" column="POSITION" /> <result property="narrow_level" column="NARROW_LEVEL" /> <result property="preoperative_timi_leve" column="PREOPERATIVE_TIMI_LEVE" /> <result property="bracket_thrombus" column="BRACKET_THROMBUS" /> <result property="branching_sick" column="BRANCHING_SICK" /> <result property="cto" column="CTO" /> <result property="ca_sick" column="CA_SICK" /> <result property="criminal_sick" column="CRIMINAL_SICK" /> <result property="pci" column="PCI" /> <result property="intraoperative_handle" column="INTRAOPERATIVE_HANDLE" /> <result property="balloon_expansion_time" column="BALLOON_EXPANSION_TIME" /> <result property="timi" column="TIMI" /> <result property="bracket_num" column="BRACKET_NUM" /> <result property="bracket_type" column="BRACKET_TYPE" /> </resultMap> <select id="selectAlltestByPatientId" parameterType="String" resultMap="AlltestResult"> SELECT * FROM registerinfo a, firstaidinfo b, outcomeinfo c LEFT JOIN outdrugdetails ON outdrugdetails.patient_id = c.patient_id, treatmentinfo d LEFT JOIN ctnts ON ctnts.ctnts_patient_id = d.patient_id LEFT JOIN ecgs ON ecgs.patient_id = d.patient_id, treatmentpciinfo e LEFT JOIN coronary_angiographie ON coronary_angiographie.ca_patient_id = e.patient_id WHERE a.patient_id = #{paientId} and a.patient_id = b.patient_id AND a.patient_id = c.patient_id AND a.patient_id = d.patient_id AND a.patient_id = e.patient_id </select> 

运行结果及报错内容

如果这个 Outdrugdetails 表里面对应的 patientId 有两条数据，目标最后的返回的数据是 1 条，但是返回了两条。

我的解答思路和尝试过的方法

我改了数据类型为 list 还是不行，sql 语句我目前只知道这么写，我试过将 select 语句嵌套在 collection 中但是报错了。现在不知道怎么解决这个问题。

我想要达到的结果

最后返回的结果可以正确的嵌套。